Last updated: 10/25/17

September 2017

Thermal State, Slab Metamorphism, and Interface Seismicity in the Cascadia Subduction Zone Based On 3‐D Modeling

Authors: Yingfeng Ji, Shoichi Yoshioka, Yuval A. Banay; First Published:18 September 2017

Machine Learning Predicts Laboratory Earthquakes

Authors: Bertrand Rouet‐Leduc, Claudia Hulbert, Nicholas Lubbers, Kipton Barros, Colin J. Humphreys, Paul A. Johnson; First Published: 22 September 2017

Mapping fluids to subduction megathrust locking and slip behavior

Authors:Demian M. Saffer; First Published:19 September 2017

Viscoelastic lower crust and mantle relaxation following the 14–16 April 2016 Kumamoto, Japan, earthquake sequence

Authors: Fred F. Pollitz, Tomokazu Kobayashi, Hiroshi Yarai, Bunichiro Shibazaki, Takumi Matsumoto; First Published: 9 September 2017

Aeromagnetic, gravity, and Differential Interferometric Synthetic Aperture Radar analyses reveal the causative fault of the 3 April 2017 Mw 6.5 Moiyabana, Botswana, earthquake

Authors: F. Kolawole, E. A. Atekwana, S. Malloy, D. S. Stamps, R. Grandin, M. G. Abdelsalam, K. Leseane, E. M. Shemang; First Published: 9 September 2017

August 2017

Control of asperities size and spacing on seismic behavior of subduction megathrusts

Authors: Fabio Corbi, Francesca Funiciello, Silvia Brizzi, Serge Lallemand, Matthias Rosenau; First Published:19 August 2017

Seismotectonics of the 2013 Lushan Mw 6.7 earthquake: Inversion tectonics in the eastern margin of the Tibetan Plateau

Authors: Renqi Lu, Xiwei Xu, Dengfa He, Suppe John, Bo Liu, Fuyun Wang, Xibin Tan, Yingqiang Li; First Published:19 August 2017

Aftershocks driven by afterslip and fluid pressure sweeping through a fault‐fracture mesh

Authors: Zachary E. Ross, Christopher Rollins, Elizabeth S. Cochran, Egill Hauksson, Jean‐Philippe Avouac, Yehuda Ben‐Zion; First Published: 19 August 2017

The postearthquake stress state on the Tohoku megathrust as constrained by reanalysis of the JFAST breakout data

Authors:Emily E. Brodsky, Demian Saffer, Patrick Fulton, Frederick Chester, Marianne Conin, Katelyn Huffman, J. Casey Moore, Hung‐Yu Wu; First Published: 26 August 2017

Do weak global stresses synchronize earthquakes?

Authors: R. Bendick, R. Bilham; First Published: 26 August 2017

Slow slip events and the 2016 Te Araroa Mw 7.1 earthquake interaction: Northern Hikurangi subduction, New Zealand

Authors: A. Koulali, S. McClusky, L. Wallace, S. Allgeyer, P. Tregoning, E. D'Anastasio, R. Benavente; First Published: 28 August 2017

Aseismic deformation associated with an earthquake swarm in the northern Apennines (Italy)

Authors: A. Gualandi, C. Nichele, E. Serpelloni, L. Chiaraluce, L. Anderlini, D. Latorre, M. E. Belardinelli, J.‐P. Avouac; First Published: 5 August 2017

Off‐fault deformations and shallow slip deficit from dynamic rupture simulations with fault zone plasticity

Authors: D. Roten, K. B. Olsen, S. M. Day; First Published: 11 August 2017

July 2017

Temporal static stress drop variations due to injection activity at The Geysers geothermal field, California

Authors: M. Staszek, B. Orlecka‐Sikora, K. Leptokaropoulos, G. Kwiatek, P. Martínez‐Garzón; First Published: 22 July 2017

Explaining extreme ground motion in Osaka basin during the 2011 Tohoku earthquake

Authors: Victor C. Tsai, Daniel C. Bowden, Hiroo Kanamori; First Published: 28 July 2017

Two regions of seafloor deformation generated the tsunami for the 13 November 2016, Kaikoura, New Zealand earthquake

Authors: Yefei Bai, Thorne Lay, Kwok Fai Cheung, Lingling Ye; First Published: 3 July 2017

Ground deformation before the 2015 eruptions of Cotopaxi volcano detected by InSAR

Authors: Anieri M. Morales Rivera, Falk Amelung, Patricia Mothes, Sang‐Hoon Hong, Jean‐Mathieu Nocquet, Paul Jarrin; First Published: 3 July 2017

Reawakening of large earthquakes in south central Chile: The 2016 Mw 7.6 Chiloé event

Authors: S. Ruiz, M. Moreno, D. Melnick, F. del Campo, P. Poli, J. C. Baez, F. Leyton, R. Madariaga; First Published: 3 July 2017

Trench motion‐controlled slab morphology and stress variations: Implications for the isolated 2015 Bonin Islands deep earthquake

Authors: Ting Yang, Michael Gurnis, Zhongwen Zhan; First Published: 3 July 2017

Influences on the location of repeating earthquakes determined from a and b value imaging

Authors: Masashi Kawamura, Kate Huihsuan Chen; First Published: 5 July 2017

Tectonic tremor and LFEs on a reverse fault in Taiwan

Authors: Ana C. Aguiar, Kevin Chao, Gregory C. Beroza; First Published: 6 July 2017

June 2017

Rupture processes of the 2016 Kumamoto earthquake sequence: Causes for extreme ground motions

Authors: Hiroaki Kobayashi, Kazuki Koketsu, Hiroe Miyake; First Published: 17 June 2017

GPS deformation related to the Mw 7.3, 2014, Papanoa earthquake (Mexico) reveals the aseismic behavior of the Guerrero seismic gap

Authors: A. Gualandi, H. Perfettini, M. Radiguet, N. Cotte, V. Kostoglodov; First Published: 27 June 2017

On the micromechanics of slip events in sheared, fluid‐saturated fault gouge

Authors: Omid Dorostkar, Robert A. Guyer, Paul A. Johnson, Chris Marone, Jan Carmeliet; First Published: 28 June 2017

Subduction of thick oceanic plateau and high‐angle normal‐fault earthquakes intersecting the slab

Authors: Ryuta Arai, Shuichi Kodaira, Tomoaki Yamada, Tsutomu Takahashi, Seiichi Miura, Yoshiyuki Kaneda, Azusa Nishizawa, Mitsuhiro Oikawa; First Published: 28 June 2017

Mapping the rheology of the Central Chile subduction zone with aftershocks

Authors: William B. Frank, Piero Poli, Hugo Perfettini; First Published: 3 June 2017

May 2017

Finite‐fault slip model of the 2016 Mw 7.5 Chiloé earthquake, southern Chile, estimated from Sentinel‐1 data

Authors: Wenbin Xu; First Published: 21 May 2017

Imaging the 2016 Mw 7.8 Kaikoura, New Zealand, earthquake with teleseismic P waves: A cascading rupture across multiple faults

Authors: Hao Zhang, Keith D. Koper, Kristine Pankow, Zengxi Ge; First Published: 21 May 2017

Detecting remotely triggered microseismicity around Changbaishan Volcano following nuclear explosions in North Korea and large distant earthquakes around the world

Authors: Guoming Liu, Chenyu Li, Zhigang Peng, Xuemei Li, Jing Wu; First Published: 28 May 2017

April 2017

Shallow episodic tremor near the Nankai Trough axis off southeast Mie prefecture, Japan

Authors: Satoshi Annoura, Tetsuo Hashimoto, Noriko Kamaya, Akio Katsumata; First Published: 24 April 2017

Interplate locking condition derived from seafloor geodetic observation in the shallowest subduction segment at the Central Nankai Trough, Japan

Authors: Kenji Yasuda, Keiichi Tadokoro, Sota Taniguchi, Hiroshi Kimura, Kenjiro Matsuhiro; First Published: 24 April 2017

Temporal variation of intermediate‐depth earthquakes around the time of the M9.0 Tohoku‐oki earthquake

Authors: Brent G. Delbridge, Saeko Kita, Naoki Uchida, Christopher W. Johnson, Toru Matsuzawa, Roland Bürgmann; First Published: 24 April 2017

Dynamically triggered slip on a splay fault in the Mw 7.8, 2016 Kaikoura (New Zealand) earthquake

AuthorsL James Hollingsworth, Lingling Ye, Jean‐Philippe Avouac; First Published: 21 April 2017

Plate coupling and strain in the far western Aleutian arc modeled from GPS data

Authors: Mikhail G. Kogan, Dmitry I. Frolov, Nikolay F. Vasilenko, Jeffrey T. Freymueller, Grigory M. Steblov, Göran Ekström, Nikolay N. Titkov, Alexandr S. Prytkov; First Published: 14 April 2017

Locating tremor using stacked products of correlations

Authors: Ka Lok Li, Hamzeh Sadeghisorkhani, Giulia Sgattoni, Olafur Gudmundsson, Roland Roberts; First Published: 14 April 2017

Integrating GPS with GLONASS for high‐rate seismogeodesy

Authors: Jianghui Geng, Peng Jiang, Jingnan Liu; First Published: 14 April 2017

Aseismic slip and seismogenic coupling in the Marmara Sea: What can we learn from onland geodesy?

Authors: E. Klein, Z. Duputel, F. Masson, H. Yavasoglu, P. Agram; First Published: 10 April 2017

March 2017

Applicability of Sentinel‐1 Terrain Observation by Progressive Scans multitemporal interferometry for monitoring slow ground motions in the San Francisco Bay Area

Authors: Manoochehr Shirzaei, Roland Bürgmann, Eric J. Fielding; First Published: 28 March 2017

On factors controlling precursor slip fronts in the laboratory and their relation to slow slip events in nature

Authors: Paul A. Selvadurai, Steven D. Glaser, Jessica M. Parker; First Published: 28 March 2017

Elastic deformation of the Australian continent induced by seasonal water cycles and the 2010–2011 La Niña determined using GPS and GRACE

Authors: Shin‐Chan Han; First Published: 28 March 2017

Subsidence at Cerro Prieto Geothermal Field and postseismic slip along the Indiviso fault from 2011 to 2016 RADARSAT‐2 DInSAR time series analysis

Authors: Sergey V. Samsonov, Wanpeng Feng, Yuri Fialko; First Published: 25 March 2017

Detection of vertical motion during a slow‐slip event off the Boso Peninsula, Japan, by ocean bottom pressure gauges

Authors: Toshinori Sato, Seiya Hasegawa, Akihiro Kono, Hajime Shiobara, Takeo Yagi, Tomoaki Yamada, Masanao Shinohara, Norihisa Usui; First Published: 25 March 2017

Enabling large‐scale viscoelastic calculations via neural network acceleration

Authors: Phoebe M. R. DeVries, T. Ben Thompson, Brendan J. Meade; First Published: 21 March 2017

Coseismic ruptures of the 24 August 2016, Mw 6.0 Amatrice earthquake (central Italy)

Authors: S. Pucci, P. M. De Martini, R. Civico, F. Villani, R. Nappi, T. Ricci, R. Azzaro, C. A. Brunori, M. Caciagli, F. R. Cinti, et al; First Published: 4 March 2017

Sibling earthquakes generated within a persistent rupture barrier on the Sunda megathrust under Simeulue Island

Authors: Paul M. Morgan, Lujia Feng, Aron J. Meltzner, Eric O. Lindsey, Louisa L. H. Tsang, Emma M. Hill; First Published: 4 March 2017

February 2017

Toward full exploitation of coherent and incoherent information in Sentinel‐1 TOPS data for retrieving surface displacement: Application to the 2016 Kumamoto (Japan) earthquake

Authors: Houjun Jiang, Guangcai Feng, Teng Wang, Roland Bürgmann; First Published: 25 February 2017

Postseismic uplift of the Andes following the 2010 Maule earthquake: Implications for mantle rheology

Authors: Shaoyang Li, Marcos Moreno, Jonathan Bedford, Matthias Rosenau, Oliver Heidbach, Daniel Melnick, Onno Oncken; First Published: 25 February 2017

Impacts of off‐fault plasticity on fault slip and interaction at the base of the seismogenic zone

Authors: Johanna M. Nevitt, David D. Pollard; First Published: 18 February 2017

Mechanical models favor a ramp geometry for the Ventura‐pitas point fault, California

Authors: Scott T. Marshall, Gareth J. Funning, Hannah E. Krueger, Susan E. Owen, John P. Loveless; First Published: 13 February 2017

Evolution of seismicity near the southernmost terminus of the San Andreas Fault: Implications of recent earthquake clusters for earthquake risk in southern California

Authors: Egill Hauksson, Men‐Andrin Meier, Zachary E. Ross, Lucile M. Jones; First Published: 9 February 2017

Coseismic deformation and triggered landslides of the 2016 Mw 6.2 Amatrice earthquake in Italy

Authors: Mong‐Han Huang, Eric J. Fielding, Cunren Liang, Pietro Milillo, David Bekaert, Douglas Dreger, Jacqueline Salzer; First Published: 4 February 2017

January 2017

Surface imprint of toroidal flow at retreating slab edges: The first geodetic evidence in the Calabrian subduction system

Authors: M. Palano, C. Piromallo, C. Chiarabba; First Published: 28 January 2017

The super‐interseismic phase of the megathrust earthquake cycle in Chile

Authors: Daniel Melnick, Marcos Moreno, Javier Quinteros, Juan Carlos Baez, Zhiguo Deng, Shaoyang Li, Onno Oncken; First Published: 27 January 2017

Intermittent tremor migrations beneath Guerrero, Mexico, and implications for fault healing within the slow slip zone

Authors: Yajun Peng, Allan M. Rubin; First Published: 26 January 2017

Fault roughness and strength heterogeneity control earthquake size and stress drop

Authors: O. Zielke, M. Galis, P. M. Mai; First Published: 26 January 2017

Oklahoma experiences largest earthquake during ongoing regional wastewater injection hazard mitigation efforts

Authors: W. L. Yeck, G. P. Hayes, D. E. McNamara, J. L. Rubinstein, W. D. Barnhart, P. S. Earle, H. M. Benz; First Published: 21 January 2017

Absence of remote earthquake triggering within the Coso and Salton Sea geothermal production fields

Authors: Qiong Zhang, Guoqing Lin, Zhongwen Zhan, Xiaowei Chen, Yan Qin, Shimon Wdowinski; First Published: 21 January 2017

Opal‐CT in chert beneath the toe of the Tohoku margin and its influence on the seismic aseismic transition in subduction zones

Authors: Jun Kameda, Atsushi Okamoto, Kiminori Sato, Koichiro Fujimoto, Asuka Yamaguchi, Gaku Kimura; First Published: 17 January 2017

Nucleation process of magnitude 2 repeating earthquakes on the San Andreas Fault predicted by rate‐and‐state fault models with SAFOD drill core data

Authors: Yoshihiro Kaneko, Brett M. Carpenter, Stefan B. Nielsen; First Published: 13 January 2017

Three‐dimensional displacements of a large volcano flank movement during the May 2010 eruptions at Pacaya Volcano, Guatemala

Authors: L. N. Schaefer, T. Wang, R. Escobar‐Wolf, T. Oommen, Z. Lu, J. Kim, P. R. Lundgren, G. P. Waite; First Published: 9 January 2017

December 2016

Dynamic triggering and earthquake swarms on East Pacific Rise transform faults

Authors: Camilla Cattania, Jeffrey J. McGuire, John A. Collins; First Published: 2016

Slip history of the 2016 Mw 7.0 Kumamoto earthquake: Intraplate rupture in complex tectonic environment

Authors: Jinlai Hao, Chen Ji, Zhenxin Yao; First Published: 2016

Evaluating models of Coulomb stress transfer: Is variable fault geometry important?

Authors: Zoe K. Mildon, Shinji Toda, Joanna P. Faure Walker, Gerald P. Roberts; First Published: 26 December 2016

Evidence of interseismic coupling variations along the Bhutan Himalayan arc from new GPS data

Authors: Anais Marechal, Stephane Mazzotti, Rodolphe Cattin, Gael Cazes, Philippe Vernant, Dowchu Drukpa, Kinzang Thinley, Alizia Tarayoun, Romain Le Roux‐Mallouf, Bal Bahadur Thapa, et al; First Published: 26 December 2016

Ground deformation and source geometry of the 24 August 2016 Amatrice earthquake (Central Italy) investigated through analytical and numerical modeling of DInSAR measurements and structural‐geological data

Authors: G. Lavecchia, R. Castaldo, R. de Nardis, V. De Novellis, F. Ferrarini, S. Pepe, F. Brozzetti, G. Solaro, D. Cirillo, M. Bonano, et al

First Published: 26 December 2016

Statistical tests of simple earthquake cycle models

Authors: Phoebe M. R. DeVries, Eileen L. Evans; First Published: 12 December 2016

November 2016

Constraining the kinematics of metropolitan Los Angeles faults with a slip‐partitioning model

Authors: S. Daout, S. Barbot, G. Peltzer, M.‐P. Doin, Z. Liu, R. Jolivet; First Published: 9 November 2016

Effects of dispersion in tsunami Green's functions and implications for joint inversion with seismic and geodetic data: A case study of the 2010 Mentawai Mw 7.8 earthquake

Authors: Linyan Li, Kwok Fai Cheung, Han Yue, Thorne Lay, Yefei Bai; First Published: 8 November 2016

October 2016

Coseismic slip and afterslip of the 2015 Mw 8.3 Illapel (Chile) earthquake determined from continuous GPS data

Authors: Mahesh N. Shrivastava, Gabriel González, Marcos Moreno, Mohamed Chlieh, Pablo Salazar, C. D. Reddy, Juan Carlos Báez, Gonzalo Yáñez, Juan González, Juan Carlos de la Llera; First Published: 28 October 2016

Slip heterogeneity and directivity of the ML 6.0, 2016, Amatrice earthquake estimated with rapid finite‐fault inversion

Authors: E. Tinti, L. Scognamiglio, A. Michelini, M. Cocco; First Published: 28 October 2016

Bimaterial interfaces in the south San Andreas Fault with opposite velocity contrasts NW and SE from San Gorgonio Pass

Authors: Pieter‐Ewald Share, Yehuda Ben‐Zion; First Published: 25 October 2016

Isolated regions of remote triggering in South/Southeast Asia following the 2012 Mw 8.6 Indian Ocean earthquake

Authors: Abhey Ram Bansal, Dongdong Yao, Zhigang Peng, Dimas Sianipar; First Published: 21 October 2016. 

Reconciling seismicity and geodetic locking depths on the Anza section of the San Jacinto fault

Authors: Junle Jiang, Yuri Fialko; First Published: 21 October 2016

A new paradigm for large earthquakes in stable continental plate interiors

Authors: E. Calais, T. Camelbeeck, S. Stein, M. Liu, T. J. Craig; First Published: 18 October 2016

State of stress in Texas: Implications for induced seismicity

Authors: Jens‐Erik Lund Snee, Mark D. Zoback; First Published: 15 October 2016

Low stress drop earthquakes in the rupture zone of the 1992 Nicaragua tsunami earthquake

Authors: Susan L. Bilek, Holly M. M. Rotman, W. Scott Phillips; First Published: 11 October 2016

Geological structures control on earthquake ruptures: The Mw7.7, 2013, Balochistan earthquake, Pakistan

Authors: A. Vallage, Y. Klinger, R. Lacassin, A. Delorme, M. Pierrot‐Deseilligny; First Published: 9 October 2016

Contribution of viscoelastic flow in earthquake cycles within the lithosphere‐asthenosphere system

Authors: Valère Lambert, Sylvain Barbot; First Published: 9 October 2016

Slip distribution of the 2014 Mw = 8.1 Pisagua, northern Chile, earthquake sequence estimated from coseismic fore‐arc surface cracks

Authors John P. Loveless, Chelsea P. Scott, Richard W. Allmendinger, Gabriel González;  First Published: 9 October 2016

Slow slip hidden in the noise: The intermittence of tectonic release

Authors: William B. Frank. First Published: 9 October 2016

Comparison of coseismic near‐field and off‐fault surface deformation patterns of the 1992 Mw 7.3 Landers and 1999 Mw 7.1 Hector Mine earthquakes: Implications for controls on the distribution of surface strain

Authors: C. W. D. Milliner, J. F. Dolan, J. Hollingsworth, S. Leprince, F. Ayoub

First Published: 7 October 2016

Stress rotations due to the M6.5 foreshock and M7.3 main shock in the 2016 Kumamoto, SW Japan, earthquake sequence

Authors: Keisuke Yoshida, Akira Hasegawa, Tatsuhiko Saito, Youichi Asano, Sachiko Tanaka, Kaoru Sawazaki, Yumi Urata, Eiichi Fukuyama

First Published: 6 October 2016

September 2016

Dynamic triggering of small local earthquakes in the central Himalaya

Authors: Manuel M. Mendoza, Abhijit Ghosh, Shyam S. Rai

First Published: 28 September 2016

The 2015 Wolf volcano (Galápagos) eruption studied using Sentinel‐1 and ALOS‐2 data

Authors: Wenbin Xu, Sigurjón Jónsson, Joël Ruch, Yosuke Aoki

First Published: 28 September 2016

Slab segmentation controls the interplate slip motion in the SW Hellenic subduction: New insight from the 2008 Mw 6.8 Methoni interplate earthquake

Authors: M. Sachpazi, M. Laigle, M. Charalampakis, D. Sakellariou, E. Flueh, E. Sokos, E. Daskalaki, A. Galvé, P. Petrou, A. Hirn

First Published: 28 September 2016

Comparisons of observed and modeled elastic responses to hydrological loading in the Amazon basin

Authors: D. M. Moreira, S. Calmant, F. Perosanz, L. Xavier, O. C. Rotunno Filho, F. Seyler, A. C. Monteiro

First Published: 28 September 2016

Footprints of past earthquakes revealed in the afterslip of the 2010 Mw 7.8 Mentawai tsunami earthquake

Authors: Lujia Feng, Sylvain Barbot, Emma M. Hill, Iwan Hermawan, Paramesh Banerjee, Danny H. Natawidjaja

First Published: 23 September 2016

Long‐lasting seismic repeaters in the Central Basin of the Main Marmara Fault

Authors: J. Schmittbuhl, H. Karabulut, O. Lengliné, M. Bouchon First Published: 23 September 2016

On a flawed conclusion that the 1255 AD earthquake ruptured 800 km of the Himalayan Frontal Thrust east of Kathmandu

Authors: Ian Pierce, Steven G. Wesnousky

Accepted manuscript online: 31 August 2016

August 2016

Repeating Seismic Events Indicate Possible Stick‐slip Behavior Before the Rausu Landslide

Authors: Masumi Yamada, Jim Mori, Yuki Matsushi

Accepted manuscript online: 31 August 2016

Slip model of the 17 November 2015 Mw = 6.5 Lefkada earthquake from the joint inversion of geodetic and seismic data

Authors: Konstantinos Chousianitis, A. Ozgun Konca, G.‐Akis Tselentis, Gerassimos A. Papadopoulos, Michail Gianniou

First Published: 14 August 2016, Vol: 43, Pages: 7973–7981, DOI: 10.1002/2016GL069764

The 2 March 2016 Wharton Basin Mw 7.8 earthquake: High stress drop north‐south strike‐slip rupture in the diffuse oceanic deformation zone between the Indian and Australian Plates

Authors: Thorne Lay, Lingling Ye, Charles J. Ammon, Audrey Dunham, Keith D. Koper

First Published: 4 August 2016, Vol: 43, Pages: 7937–7945, DOI: 10.1002/2016GL069931

July 2016

Revisiting the Canterbury earthquake sequence after the 14 February 2016 Mw 5.7 event

Authors: Matthew W. Herman, Kevin P. Furlong

First Published: 28 July 2016, Vol: 43, Pages: 7503–7510, DOI: 10.1002/2016GL069528

Multiple fault slip triggered above the 2016 Mw 6.4 MeiNong earthquake in Taiwan

Authors: Mong‐Han Huang, Hsin Tung, Eric J. Fielding, Hsin‐Hua Huang, Cunren Liang, Chung Huang, Jyr‐Ching Hu

First Published: 20 July 2016, Vol: 43, Pages: 7459–7467, DOI: 10.1002/2016GL069351

Stress drop estimates and hypocenter relocations of induced seismicity near Crooked Lake, Alberta

Authors: Fiona Clerc, Rebecca M. Harrington, Yajing Liu, Yu Jeffrey Gu

First Published: 14 July 2016, Vol: 43, Pages: 6942–6951, DOI: 10.1002/2016GL069800

Can slip heterogeneity be linked to earthquake recurrence?

Authors: Kate Huihsuan Chen, Iyin Chen, Ahyi Kim

First Published: 12 July 2016, Vol: 43, Pages: 6916–6923, DOI: 10.1002/2016GL069516

Break of slope in earthquake size distribution and creep rate along the San Andreas Fault system

Authors: Inessa Vorobieva, Peter Shebalin, Clément Narteau

First Published: 8 July 2016, Vol: 43, Pages: 6869–6875, DOI: 10.1002/2016GL069636

GPS constraints on broad scale extension in the Ethiopian Highlands and Main Ethiopian Rift

Authors: Yelebe Birhanu, Rebecca Bendick, Shimeles Fisseha, Elias Lewi, Michael Floyd, Robert King, Robert Reilinger

First Published: 4 July 2016, Vol: 43, Pages: 6844–6851, DOI: 10.1002/2016GL069890

Evidence for the release of long‐term tectonic strain stored in continental interiors through intraplate earthquakes

Authors: T. J. Craig, E. Calais, L. Fleitout, L. Bollinger, O. Scotti

First Published: 4 July 2016, Vol: 43, Pages: 6826–6836, DOI: 10.1002/2016GL069359

Spatial variations in fault friction related to lithology from rupture and afterslip of the 2014 South Napa, California, earthquake

Authors: Michael A. Floyd, Richard J. Walters, John R. Elliott, Gareth J. Funning, Jerry L. Svarc, Jessica R. Murray, Andy J. Hooper, Yngvar Larsen, Petar Marinkovic, Roland Bürgmann, et al

First Published: 2 July 2016, Vol: 43, Pages: 6808–6816, DOI: 10.1002/2016GL069428

June 2016

Depth migration of seasonally induced seismicity at The Geysers geothermal field

Authors: Christopher W. Johnson, Eoghan J. Totten, Roland Bürgmann

First Published: 24 June 2016, Vol: 43, Pages: 6196–6204, DOI: 10.1002/2016GL069546

The 2015 Mw 7.1 earthquake on the Charlie‐Gibbs transform fault: Repeating earthquakes and multimodal slip on a slow oceanic transform

Authors: K. Aderhold, R. E. Abercrombie

First Published: 20 June 2016, Vol: 43, Pages: 6119–6128, DOI: 10.1002/2016GL068802

Paleoseismic evidence of a giant medieval earthquake in the eastern Himalaya

Authors: Rajeeb Lochan Mishra, I. Singh, A. Pandey, P. S. Rao, H. K. Sahoo, R. Jayangondaperumal

First Published: 11 June 2016, Vol: 43, Pages: 5707–5715, DOI: 10.1002/2016GL068739

Background seismicity in Boso Peninsula, Japan: Long‐term acceleration, and relationship with slow slip events

Authors: T. Reverso, D. Marsan, A. Helmstetter, B. Enescu

First Published: 4 June 2016, Vol: 43, Pages: 5671–5679, DOI: 10.1002/2016GL068524

May 2016

Seismic evidence for tearing in the subducting Indian slab beneath the Andaman arc

Authors: Prakash Kumar, G. Srijayanthi, M. Ravi Kumar

First Published: 18 May 2016, Vol: 43, Pages: 4899–4904, DOI: 10.1002/2016GL068590

Systematic correlations of the earthquake frequency‐magnitude distribution with the deformation and mechanical regimes in the Taiwan orogen

Authors: Yen‐Ling Chen, Shu‐Huei Hung, Juen‐Shi Jiang, Ling‐Yun Chiao

First Published: 28 May 2016, Vol: 43, Pages: 5017–5025, DOI: 10.1002/2016GL069020

Heterogeneous rheology controlled postseismic deformation of the 2011 Tohoku‐Oki earthquake

Authors: Jun Muto, Bunichiro Shibazaki, Takeshi Iinuma, Yoshihiro Ito, Yusaku Ohta, Satoshi Miura, Yoshihiko Nakai

First Published: 27 May 2016, Vol: 43, Pages: 4971–4978, DOI: 10.1002/2016GL068113

Kinematically consistent models of viscoelastic stress evolution

Authors: Phoebe M. R. DeVries, Brendan J. Meade

First Published: 4 May 2016, Vol: 43, Pages: 4205–4214, DOI: 10.1002/2016GL068375. 

Creep and locking of a low‐angle normal fault: Insights from the Altotiberina fault in the Northern Apennines (Italy)

Authors: L. Anderlini, E. Serpelloni, M. E. Belardinelli

First Published: 7 May 2016, Vol: 43, Pages: 4321–4329, DOI: 10.1002/2016GL068604

Fault slip controlled by stress path and fluid pressurization rate

Authors: Melodie E. French, Wenlu Zhu, Jeremy Banker

First Published: 7 May 2016, Vol: 43, Pages: 4330–4339, DOI:10.1002/2016GL068893

March 2016

Fault interactions and triggering during the 10 January 2012 Mw 7.2 Sumatra earthquake

Authors: Wenyuan Fan, Peter M. Shearer

First Published: 8 March 2016; Vol: 43; Pages: 1934–1942; DOI: 10.1002/2016GL067785.

Ongoing deformation of Antarctica following recent Great Earthquakes

Authors: Matt A. King, Alvaro Santamaría‐Gómez

First Published: 6 March 2016; Vol: 43; Pages: 1918–1927; DOI: 10.1002/2016GL067773.

February 2016

Constraints on the source parameters of low‐frequency earthquakes on the San Andreas Fault

Authors: Amanda M. Thomas, Gregory C. Beroza, David R. Shelly

First Published: 17 February 2016; Vol: 43; Pages: 1464–1471; DOI: 10.1002/2015GL067173.

Source model of the 2015 Mw 6.4 Pishan earthquake constrained by interferometric synthetic aperture radar and GPS: Insight into blind rupture in the western Kunlun Shan

Authors: Ping He, Qi Wang, Kaihua Ding, Min Wang, Xuejun Qiao, Jie Li, Yangmao Wen, Caijun Xu, Shaomin Yang, Rong Zou

First Published: 20 February 2016; Vol: 43; Pages: 1511–1519; DOI: 10.1002/2015GL067140.

Dynamically triggered slip leading to sustained fault gouge weakening under laboratory shear conditions

Authors: P. A. Johnson, J. Carmeliet, H. M. Savage, M. Scuderi, B. M. Carpenter, R. A. Guyer, E. G. Daub, C. Marone

First Published: 26 February 2016; Vol: 43; Pages: 1559–1565; DOI: 10.1002/2015GL067056. 

Slip segmentation and slow rupture to the trench during the 2015,Mw8.3 Illapel, Chile earthquake

Authors: Diego Melgar, Wenyuan Fan, Sebastian Riquelme, Jianghui Geng, Cunren Liang, Mauricio Fuentes, Gabriel Vargas, Richard M. Allen, Peter M. Shearer, Eric J. Fielding

First Published: 4 February 2016; Vol: 43; Pages: 961–966; DOI: 10.1002/2015GL067369.

Slow slip event within a gap between tremor and locked zones in the Nankai subduction zone

Authors: Ryota Takagi, Kazushige Obara, Takuto Maeda

First Published: 4 February 2016; Vol: 43; Pages: 1066–1074; DOI: 10.1002/2015GL066987.

Wastewater disposal and earthquake swarm activity at the southern end of the Central Valley, California

Authors: T. H. W. Goebel, S. M. Hosseini, F. Cappa, E. Hauksson, J. P. Ampuero, F. Aminzadeh, J. B. Saleeby

First Published: 4 February 2016; Vol: 43; Pages: 1092–1099; DOI: 10.1002/2015GL066948.

January 2016

The 2015 Illapel earthquake, central Chile: A type case for a characteristic earthquake?

Authors: F. Tilmann, Y. Zhang, M. Moreno, J. Saul, F. Eckelmann, M. Palo, Z. Deng, A. Babeyko, K. Chen, J. C. Baez, et al

First Published: 19 January 2016; Vol: 43; Pages: 574–583; DOI: 10.1002/2015GL066963

Real‐time capture of seismic waves using high‐rate multi‐GNSS observations: Application to the 2015 Mw 7.8 Nepal earthquake

Authors: Tao Geng, Xin Xie, Rongxin Fang, Xing Su, Qile Zhao, Gang Liu, Heng Li, Chuang Shi, Jingnan Liu

First Published: 14 January 2016; Vol: 43; Pages: 161–167; DOI: 10.1002/2015GL067044

Small interseismic asperities and widespread aseismic creep on the northern Japan subduction interface

Authors: Kaj M. Johnson, Andreas Mavrommatis, Paul Segall

First Published: 9 January 2016; Vol: 43; Pages: 135–143; DOI: 10.1002/2015GL066707

December 2015

A paleogeodetic record of variable interseismic rates and megathrust coupling at Simeulue Island, Sumatra

Authors: Louisa L. H. Tsang, Aron J. Meltzner, Emma M. Hill, Jeffrey T. Freymueller, Kerry Sieh

First Published: 19 December 2015; Vol: 42; Pages: 10,585–10,594; DOI: 10.1002/2015GL066366

Static stress drop in the Mw 9 Tohoku‐oki earthquake: Heterogeneous distribution and low average value

Authors: Lonn Brown, Kelin Wang, Tianhaozhe Sun

First Published: 23 December 2015; Vol: 42; Pages: 10,595–10,600; DOI: 10.1002/2015GL066361

A statistical model for seismic hazard assessment of hydraulic‐fracturing‐induced seismicity

Authors: T. Hajati, C. Langenbruch, S. A. Shapiro

First Published: 23 December 2015; Vol: 42; Pages: 10,601–10,606; DOI: 10.1002/2015GL066652

Influence of anthropogenic groundwater unloading in Indo‐Gangetic plains on the 25 April 2015 Mw 7.8 Gorkha, Nepal earthquake

Authors: Bhaskar Kundu, Naresh Krishna Vissa, V. K. Gahalaut

First Published: 23 December 2015; Vol: 42; Pages: 10,607–10,613; DOI: 10.1002/2015GL066616;

Seismotectonics of southern Haiti: A new faulting model for the 12 January 2010 M7.0 earthquake

Authors: Newdeskarl Saint Fleur, Nathalie Feuillet, Raphaël Grandin, Eric Jacques, Jennifer Weil‐Accardo, Yann Klinger

First Published: 12 December 2015; Vol: 42; Pages: 10,273–10,281; DOI: 10.1002/2015GL065505; 

November 2015

Long‐term acceleration of aseismic slip preceding the Mw 9 Tohoku‐oki earthquake: Constraints from repeating earthquakes

Authors: Andreas P. Mavrommatis, Paul Segall, Naoki Uchida, Kaj M. Johnson

First Published: 19 November 2015; Vol: 42; Pages: 9717–9725; DOI: 10.1002/2015GL066069

October 2014

The Mw 6.5 offshore Northern California earthquake of 10 January 2010: Ordinary stress drop on a high-strength fault

Meng Wei1,* and Jeffrey J. McGuire2

The 10 January 2010 Mw 6.5 earthquake offshore Northern California is one of the first intraplate earthquakes in oceanic lithosphere to be well captured by a GPS network. It presents an opportunity to evaluate rupture mechanics on a high-strength fault. Static inversion of the coseismic displacements shows that the slip peaks at the same depth as the expected strength envelope, where the differential stresses can be as high as 600 MPa. Laboratory experiments on peridotite predict dramatic dynamic weakening at these conditions. The observed ordinary stress drop, 2–20 MPa, may indicate that the lithosphere is much weaker than strength envelope predicts or that the failure mechanisms seen in the laboratory are not occurring during the rupture. The GPS observations show very little postseismic signal indicating that if a shear zone exists beneath the coseismic rupture, it operates at significantly greater stress levels than the coseismic stress change.

Broadscale postseismic gravity change following the 2011 Tohoku-Oki earthquake and implication for deformation by viscoelastic relaxation and afterslip

Shin-Chan Han1,*, Jeanne Sauber1 and Fred Pollitz2

The analysis of GRACE gravity data revealed postseismic gravity increase by 6 μGal over a 500 km scale within a couple of years after the 2011 Tohoku-Oki earthquake, which is nearly 40–50% of the coseismic gravity change. It originates mostly from changes in the isotropic component corresponding to the Mrr moment tensor element. The exponential decay with rapid change in a year and gradual change afterward is a characteristic temporal pattern. Both viscoelastic relaxation and afterslip models produce reasonable agreement with the GRACE free-air gravity observation, while their Bouguer gravity patterns and seafloor vertical deformations are distinctly different. The postseismic gravity variation is best modeled by the biviscous relaxation with a transient and steady state viscosity of 1018 and 1019 Pa s, respectively, for the asthenosphere. Our calculated higher-resolution viscoelastic relaxation model, underlying the partially ruptured elastic lithosphere, yields the localized postseismic subsidence above the hypocenter reported from the GPS-acoustic seafloor surveying.

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Interplate locking condition derived from seafloor geodetic data at the northernmost part of the Suruga Trough, Japan

Kenji Yasuda1,*, Keiichi Tadokoro1, Ryoya Ikuta2, Tsuyoshi Watanabe1, Satoru Nagai1, Takashi Okuda1, Cosmo Fujii1 and Keizo Sayanagi3

We observed seafloor crustal deformation at two observation sites on opposite sides of the Suruga Trough off Japan from 2005 to 2011 to investigate the interplate locking condition at the source region of the anticipated great subduction earthquake, named Tokai earthquake. We estimated the displacement velocity vectors relative to the Amurian Plate on the basis of repeated observations. Our results at the two points, Suruga northeast and Suruga northwest (SNW) were 42 ± 8 mm/yr toward N94 ± 3°W and 39 ± 11 mm/yr toward N84 ± 9°W, respectively. These directions are the same as those measured at on-land GPS stations. The magnitudes of the velocity vectors indicate a significant shortening of approximately 4 mm/yr between SNW and on-land GPS stations located to the west of the Suruga Trough. The results show that the plate interface is strongly locked (no slip) shallower than the source region of the anticipated Tokai earthquake.

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Evidence of viscoelastic deformation following the 2011 Tohoku-Oki earthquake revealed from seafloor geodetic observation

Shun-ichi Watanabe1,*, Mariko Sato1,Masayuki Fujita1, Tadashi Ishikawa1,Yusuke Yokota1, Naoto Ujihara1 and Akira Asada2

The GPS/acoustic seafloor positioning has detected significant postseismic movements after the 2011 Tohoku-Oki earthquake (M9.0), just above the source region off the Pacific coast of eastern Japan. In contrast to the coastal Global Navigation Satellite Systems sites where trenchward-upward movements were reported, the offshore sites above the main rupture zone in the northern part of the source region exhibit landward displacements of tens of centimeters with significant subsidence from almost 3 years of repeated observations. At the sites above around the edge of the main rupture zone, smaller amount of trench-normal movements was found. Although the terrestrial movements were reasonably interpreted by afterslip beneath the coastal area, these offshore results are rather consistent with effects predicted from viscoelastic relaxation in the upper mantle, providing definitive evidence of its occurrence. On the other hand, the results in the southern part of the source region imply superposition of effects from viscoelastic relaxation and afterslip.

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Bayesian confidence intervals for the magnitude of the largest aftershock

Robert Shcherbakov1,2,*

Aftershock sequences, which follow large earthquakes, last hundreds of days and are characterized by well-defined frequency-magnitude and spatio-temporal distributions. The largest aftershocks in a sequence constitute significant hazard and can inflict additional damage to infrastructure that is already affected by the main shock. Therefore, the estimation of the magnitude of a possible largest aftershock in a sequence is of high importance. In this work, a Bayesian predictive distribution and the corresponding confidence intervals for the magnitude of the largest expected aftershock in a sequence are derived using the framework of Bayesian analysis and extreme value statistics. The analysis is applied to 19 well-known aftershock sequences worldwide to construct retrospectively the confidence intervals for the magnitude of the subsequent largest aftershock by using the statistics of early aftershocks in the sequences.

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September 2014

Co- and Postseismic motion of a landslide; observations, modelling and analogy with tectonic faults.

We document the first time‐series of a landslide reactivation by an earthquake, using continuous GPS measurements over the Maca landslide (Peru). Our survey shows a coseismic response of the landslide of about 2cm, followed by a relaxation period of 5weeks during which postseismic slip is three times greater than the coseismic displacement itself. Our results confirm the coseismic activation of landslides and provide the first observation of a postseismic displacement. These observations are consistent with a mechanical model where slip on the landslide basal interface is governed by rate and state friction, analogous to the mechanics of creeping tectonic faults, opening new perspectives to study the mechanics of landslides and active faults.

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Foreshock activity related to enhanced aftershock production

Foreshock activity sometimes precedes the occurrence of large earthquakes, but the nature of this seismicity is still debated, and whether it marks transient deformation and/or slip nucleation is still unclear. We here study at the world wide scale how foreshock occurrence affects the post‐seismic phase, and find a significant positive correlation between foreshock and aftershock activities: earthquakes preceded by accelerating seismicity rates produce 40 % more aftershocks on average, and the length of the aftershock zone after 20days is 20 % larger. These observations cannot be reproduced by standard earthquake clustering models that predict the accelerating pattern of foreshock occurrence but not its impact on aftershock activity. This strongly suggests that slow deformation transients, possibly related to episodic creep, could initiate prior to the mainshock and extend past the co‐seismic phase, resulting in compound ruptures that include a very long period (up to tens of days) component.

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Fault constitutive relations inferred from the 2009-2010 slow slip event in Guerrero, Mexico

The spatiotemporal evolution of stress state is analyzed during the 2009–2010 Slow Slip Event (SSE) of Guerrero, Mexico, based on the kinematic inversion results and using an integral expression for stress changes. A linear slip weakening behavior is generally observed during the SSE with an average slope of −0.5 ± 0.2MPa/m regardless the perturbation due to the 27 February 2010 Mw = 8.8 Maule, Chile earthquake. This slope remains unchanged before and after the Maule earthquake. However, for some area, the friction behavior changes from slip hardening to slip weakening following the Maule earthquake. The complex trajectory between shear stress and slip velocity is fitted with a rate- and state friction law through an inversion. The direct (rate) effect (parameter A) is found to be very small, lower by an order of magnitude than the evolutional (state) effect (parameter B). The characteristic length L is obtained as 5 cm on average.

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Spatiotemporal analysis and interpretation of 1993–2013 ground deformation at Campi Flegrei, Italy, observed by advanced DInSAR

Campi Flegrei is one of the most hazardous volcanic areas in the world because of its close proximity to the city of Naples. Here we apply the multidimensional small baseline subset (MSBAS) differential interferometric synthetic aperture radar (DInSAR) technique to obtain vertical and horizontal components of ground deformation for Campi Flegrei at high spatial and temporal resolutions that span, for the first time, 20 years. The area underwent continuous subsidence from 1993 through 1999. Moderate uplift began in 2010 and substantially increased through 2012, reaching approximately 13cm by 2013. We model the observed deformation to determine source parameters for subsidence and uplift epochs. Both the inflation and deflation mechanisms involve large, extended sources in a layered hydrothermal system whose location is controlled by the caldera structure and stratigraphy. The temporal resolution of MSBAS approaches that of GPS daily time series, with superior precision and spatial resolution, making it an excellent alternative for volcano monitoring.

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Removal of systematic seasonal atmospheric signal from interferometric synthetic aperture radar ground deformation time series

Applying the Multidimensional Small Baseline Subset interferometric synthetic aperture radar algorithm to about 1500 Envisat and RADARSAT‐2 interferograms spanning 2003–2013, we computed time series of ground deformation over Naples Bay Area in Italy. Two active volcanoes, Vesuvius and Campi Flegrei, are located in this area in close proximity to the densely populated city of Naples. For the first time, and with remarkable clarity, we observed decade‐long elevation‐dependent seasonal oscillations of the vertical displacement component with a peak‐to‐peak amplitude of up to 3.0 cm, substantially larger than the long‐term deformation rate (<0.6 cm/yr). Analysis, utilizing surface weather and radiosonde data, linked observed oscillations with seasonal fluctuations of water vapor, air pressure, and temperature in the lower troposphere. The modeled correction is in a good agreement with observed results. The mean, absolute, and RMS differences are 0.014 cm, 0.073 cm, and 0.087 cm, respectively. Atmospherically corrected time series confirmed continuing subsidence at Vesuvius previously observed by geodetic techniques.

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October 2013

Evidence of active mantle flow beneath South China

" The India-Eurasia collision is responsible for producing the Himalayan Mountains and Tibetan plateau and has been hypothesized to have significant far field influences, including driving the Baikal rift and the eastward extrusion of South China. However, quantification of lithospheric buoyancy forces and integrated effect of tractions acting at base of the lithosphere are unable to explain the observed surface motions within South China. We present 198 new SKS shear wave splitting observations beneath South China and invert these data along with published GPS data to solve for the subasthenospheric flow field beneath South China to assess the role of small-scale convection here. We find a 15–20mm/yr southwestward-directed mantle flow toward the Burma slab. This flow is consistent with the mantle response of slab retreat over the past 25Ma, and counter flow due to subduction of Burma/Sunda slabs demonstrating the importance of localized mantle convection on present-day plate motions. "

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Comprehensive model of short- and long-term slow slip events in the Shikoku region of Japan, incorporating a realistic plate configuration

" We numerically simulate slow slip events (SSEs) in the Shikoku region of Japan, incorporating the configuration of the subducting plate. We adopt a rate- and state-dependent friction law with cutoff velocities, assuming a frictional parameter distribution based on observed long-term SSEs and nonvolcanic tremors that reflects the slip of short-term SSEs. Our model reproduces recurrences of long- and short-term SSEs and segments of short-term SSEs. In our simulation, short-term SSEs' transition from episodic to continuous slip is reproduced. This feature is consistent with tremor activity recently reported in both Shikoku and Cascadia. In addition to the long-term SSEs in the Bungo Channel, our model also reproduces newly found long-term SSEs in central Shikoku and predicts that these SSEs recur during the interseismic period between megathrust earthquakes. Our model comprehensively reproduces various SSEs and their characteristics as reported in the Shikoku region. "

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Seismic evidence for lithospheric modification beneath the Mojave Neovolcanic Province, Southern California

" The Mojave Neovolcanic Province (MNVP), located in the Mojave block of southern California, comprises late Miocene to Quaternary small-volume basaltic centers. Geochemistry indicates an asthenospheric source for the MNVP beginning in the late Miocene, but no physical evidence of missing mantle lithosphere has been presented. We utilize receiver functions and ambient noise tomography to image the lithosphere beneath the Mojave block. Regionally, we find thin crust that thickens distal to sites of MNVP volcanism. Shear wave velocities between 40 and 75km depth are consistent with the presence of mantle lithosphere in the southern Mojave block and very thin or missing mantle lithosphere to the north. With one exception, MNVP volcanoes lie along this sharp boundary. Our observations, together with the established geologic history and geochemistry of the MNVP, can be explained by small-scale edge-driven convection producing ongoing lithospheric removal within the Mojave block. Our results provide another example of lithospheric instability that occurs in response to rapid changes in mantle dynamics induced by major changes in tectonic plate geometry. "

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Spatial and temporal patterns of simulated slow slip events on the Cascadia megathrust

" In recent years, it has been discovered that sections of the subduction interface slip aseismically in slow slip events, during which stress is intermittently transferred to the section of the subduction zone that generates large or great earthquakes. Within the Cascadia subduction zone, the magnitude and frequency of SSEs and accompanying tectonic tremor exhibit complex patterns that vary systematically with depth. However, the loading mechanisms and interactions that precede great subduction earthquakes are poorly understood. Here we present results from physics-based simulations that reproduce the continuum of SSE characteristics reported for the Cascadia subduction zone. The simulations provide a basis for understanding the interactions that control both the observed complex patterns of SSEs and stress transfer to the seismogenic section that produce great earthquakes. "

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Recovering coseismic point ground tilts from collocated high-rate GPS and accelerometers

" Rotational along with translational and strain measurements are essential for a complete description of the motion of a deformable body in a seismic event. We propose a new seismogeodetic approach where collocated high-rate GPS and accelerometer measurements are combined to estimate permanent and dynamic coseismic ground tilts at a point, whereas at present, only dynamic tilts are measured with either a dense seismic array or an expensive ring laser gyroscope. We estimate point tilts for a five-story structure on a shake table subjected to 13 earthquake strong motion records of increasing intensity. For the most intense record from the 2002 M7.9 Denali earthquake, we observe a peak-to-peak dynamic tilt of 0.12° and a permanent tilt of 0.16° for the structure's roof. Point tilts derived from networks of collocated GPS and accelerometers can be used to estimate the rotational component of the seismic wavefield for improved earthquake source characterization. "

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Modeling dynamic triggering of tectonic tremor using a brittle-ductile friction model

" We study the physics of dynamically triggered tectonic tremor by applying a brittle-ductile friction model in which we conceptualize the tremor source as a rigid block subject to driving and frictional forces. To simulate dynamic triggering of tremor, we apply a stress perturbation that mimics the surface waves of remote earthquakes. The tectonic and wave perturbation stresses define a phase space that demonstrates that both the timing and amplitude of the dynamic perturbations control the fundamental characteristics of triggered tremor. Tremor can be triggered instantaneously or with a delayed onset if the dynamic perturbation significantly alters the frictional state of the tremor source. "

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Scaling relations of seismic moment, rupture area, average slip, and asperity size for M~9 subduction-zone earthquakes

" Scaling relations for seismic moment M0, rupture area S, average slip D, and asperity size Sa were obtained for large, great, and giant (Mw=6.7–9.2) subduction-zone earthquakes. We compiled the source parameters for seven giant (Mw~9) earthquakes globally for which the heterogeneous slip distributions were estimated from tsunami and geodetic data. We defined Sa for subfaults exhibiting slip greater than 1.5 times D. Adding 25 slip models of 10 great earthquakes around Japan, we recalculated regression relations for 32 slip models: S=1.34×10−10M02/3, D=1.66×10−7M01/3, Sa=2.81×10−11M02/3, and Sa/S=0.2, where S and Sa are in square kilometers, M0 is in newton meters, and D is in meters. These scaling relations are very similar to those obtained by Murotani et al. (2008) for large and great earthquakes. Thus, both scaling relations can be used for future tsunami hazard assessment associated with a giant earthquake. "

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Characterization of nucleation during laboratory earthquakes

" We observe the nucleation phase of in-plane ruptures in the laboratory. We show that the nucleation is composed of two distinct phases, a quasi-static and an acceleration stage, followed by dynamic propagation. We propose an empirical model which describes the rupture length evolution: The quasi-static phase is described by an exponential growth while the acceleration phase is described by an inverse power law of time. The transition from quasi-static to accelerating rupture is related to the critical nucleation length, which scales inversely with normal stress in accordance with theoretical predictions, and to a critical surfacic power, which may be an intrinsic property of the interface. Finally, we discuss these results in the frame of previous studies and propose a scaling up to natural earthquake dimensions. "

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Shape evolution and finite deformation pattern in analog experiments of lithosphere necking

" Lithosphere necking evolution determines the 3-D architecture of crustal and upper mantle thinning and related basins, and the heat flow distribution in rifted regions. Despite a large number of studies, lithosphere necking evolution is still a matter of debate. We present the result from lithospheric-scale analog models designed for investigating the necking shape during extension and the vertical distribution of finite deformation in the mechanical lithosphere. In our experiments, lithosphere necking is asymmetric and, in particular, the 3-D distribution of thinning is cylindrical in the crust and very heterogeneous in the mantle. Overall, the evolution of rifting and necking progresses from delocalized to localized deformation. "

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Rupture complexity of the Mw 8.3 sea of okhotsk earthquake: Rapid triggering of complementary earthquakes?

" We derive a finite slip model for the 2013 Mw 8.3 Sea of Okhotsk Earthquake (Z=610km) by inverting calibrated teleseismic P waveforms. The inversion shows that the earthquake ruptured on a 10° dipping rectangular fault zone (140km×50km) and evolved into a sequence of four large sub-events (E1–E4) with an average rupture speed of 4.0km/s. The rupture process can be divided into two main stages. The first propagated south, rupturing sub-events E1, E2, and E4. The second stage (E3) originated near E2 with a delay of 12s and ruptured northward, filling the slip gap between E1 and E2. This kinematic process produces an overall slip pattern similar to that observed in shallow swarms, except it occurs over a compressed time span of about 30s and without many aftershocks, suggesting that sub-event triggering for deep events is significantly more efficient than for shallow events. "

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September 2013

A slower fault may produce a smaller preseismic moment rate: Non-1/tf acceleration of moment rate during nucleation and dependency on the background slip rate

" A recent global study has revealed that seismicity near the hypocenter prior to large earthquakes, which could be a proxy for preseismic moment rate, accelerates before interplate earthquakes, while it rarely does before intraplate earthquakes. Understanding the amplitude of preseismic deformation is important in assessing the possibility of its detection. For a class of rate-state friction laws without a characteristic speed-related parameter (e.g., aging law and slip law), a dimensional analysis has shown that if the moment rate increases more mildly than 1/tf where tf is the time-to-failure, then the amplitude of preseismic moment rate is smaller for a smaller quasistatic slip rate. Three-dimensional numerical simulations have revealed that the aging law yields 1/tf acceleration, while the slip law causes milder acceleration. If the latter is the case, faults with very low long-term slip rates (e.g., intraplate faults) may have very small preseismic moment rates. "

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Along-strike structural changes controlled by dehydration-related fluids within the Philippine Sea plate around the segment boundary of a megathrust earthquake beneath the Kii peninsula, southwest Japan

" Active and passive seismic experiments in the Kii Peninsula, southwest Japan, revealed prominent structural features around the segment boundary of a megathrust earthquake associated with the subduction of the Philippine Sea Plate (PHS). A distinct reflection band in the uppermost part of the PHS shows significant lateral variation along its strike. The thicker reflection band, which corresponds to the deeper extension of the fault area of the 1944 Tonankai Earthquake, is interpreted to be a zone of high pore fluid pressure, causing a state of conditionally stable slip on the plate boundary by the reduction in effective normal stress. A thinner reflective band corresponds to the deepest part of the rupture area of the 1946 Nankai earthquake, where plate coupling is stronger due to less effect of fluids. This along-strike structural variation controls the differences in frictional properties and the lateral limit of rupturing along the plate boundary. "

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Permanently enhanced dynamic triggering probabilities as evidenced by two M7.5 earthquakes

" The 2012 M7.7 Haida Gwaii earthquake radiated waves that likely dynamically triggered the 2013 M7.5 Craig earthquake, setting two precedents. First, the triggered earthquake is the largest dynamically triggered shear failure event documented to date. Second, the events highlight a connection between geologic structure, sedimentary troughs that act as waveguides, and triggering probability. The Haida Gwaii earthquake excited extraordinarily large waves within and beyond the Queen Charlotte Trough, which propagated well into mainland Alaska and likely triggering the Craig earthquake along the way. Previously, focusing and associated dynamic triggering have been attributed to unpredictable source effects. This case suggests that elevated dynamic triggering probabilities may exist along the many structures where sedimentary troughs overlie major faults, such as subduction zones’ accretionary prisms and transform faults’ axial valleys. Although data are sparse, I find no evidence of accelerating seismic activity in the vicinity of the Craig rupture between it and the Haida Gwaii earthquake. "

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Two-dimensional viscosity structure of the northeastern Japan islands arc-trench system

"Two-dimensional viscosity profiles were constructed for the northeastern Japan islands arc-trench system covering the source area of the 2011 Tohoku-Oki earthquake. From seismologically determined models of lithospheric structure, experimentally derived constitutive laws of various rocks, and densely measured geothermal gradient data, we have predicted the steady state effective viscosity across the subduction zone. The profile reveals strong lateral viscosity gradients both parallel and normal to the trench axis. The detailed viscosity structures presented here contribute to accurate evaluation of viscoelastic relaxation components when modeling geodetically measured postseismic deformation at high spatial and temporal resolution."

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Characteristics of a tsunamigenic megasplay fault in the Nankai Trough

"Slip on the shallow part of a megasplay fault that is an out-of-sequence thrust and branch of the main subduction plate boundary can cause devastating tsunamis after earthquakes. We analyzed the three-dimensional geometry, including dip amount and azimuths, roughness distributions, and thickness variations, of the shallow part of a megasplay fault in the Nankai Trough using a three-dimensional seismic data set. The fault is divided into three zones based on its geometry: thick, smooth, and simply convex in the east; complexly curved in the middle; and thin and kinked in the west. Results of scientific drilling indicate that the eastern region of the fault is most active, and local heterogeneities in fault geometry, including roughness and thickness, may control the slip on this part of the fault. The present findings can be used to evaluate the risk of future tsunamis arising from movement on shallow thrust faults at subduction margins."

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Earthquake early warning for southern Iberia: A P wave threshold-based approach

" The south of the Iberian Peninsula is a region in which large, damaging earthquakes occur separated by long time intervals. An example was the great 1755 Lisbon earthquake (intensity Imax=X) which occurred SW of San Vicente Cape (SW Iberian Peninsula). Due to this risk of damaging earthquakes, the implementation of Earthquake Early Warning System (EEWS) technologies is of considerable interest. With the aim of investigating the feasibility of an EEWS in this region of the Iberian Peninsula, empirical scaling relationships have been derived between the early warning parameters and the earthquake size and/or its potential damaging effects for this region. An appropriate and suitable strategy is proposed for an EEWS in the SW Iberian Peninsula, which takes into account the limitations of the existing seismological networks. "

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Lithospheric fabric variations in central North America: Influence of rifting and Archean tectonic styles

"Upper mantle fabric, as detected by shear wave splitting measurements, records lithospheric strain history that may be related to past tectonic events. We present SKS (core-refracted shear wave) splitting measurements taken around the western Great Lakes, North America: the Archean Superior Province (SP) and surroundings. We analyze 40 sites in the USA and 5 in Canada and outline a region of strong anisotropy corresponding to a high-velocity zone in tomographic models, which we dub the Western Superior Mantle Anomaly (WSMA) and interpret to represent a preserved fabric from accretion of the SP. To the southwest of the WSMA, we locate a region of rotated fast direction corresponding to a linear low-velocity feature observed by tomography and which may represent a failed branch of the Mid-Continent Rift. Further south, within the Minnesota River Valley Terrane, the split times drop to near zero, suggesting isotropic lithosphere resulting from vertical (diapiric) rather than horizontal tectonic processes."

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August 2013

New ultrahigh-resolution picture of Earth's gravity field

We provide an unprecedented ultrahigh resolution picture of Earth's gravity over all continents and numerous islands within ±60° latitude. This is achieved through augmentation of new satellite and terrestrial gravity with topography data and use of massive parallel computation techniques, delivering local detail at ~200 m spatial resolution. As such, our work is the first-of-its-kind to model gravity at unprecedented fine scales yet with near-global coverage. The new picture of Earth's gravity encompasses a suite of gridded estimates of gravity accelerations, radial and horizontal field components, and quasi-geoid heights at over 3 billion points covering 80% of Earth's land masses. We identify new candidate locations of extreme gravity signals, suggesting that the Committee on Data for Science and Technology standard for peak-to-peak variations in free-fall gravity is too low by about 40%. The new models are beneficial for a wide range of scientific and engineering applications and freely available to the public.

Bias in estimates of lithosphere viscosity from interseismic deformation

The estimation of uniform viscosities representing the lower crust and uppermost mantle from postseismic or interseismic deformation (i.e., apparent viscosities) is inherently biased with respect to a depth dependence of the viscosities within each layer. Estimates are biased toward a more viscous lower crust or a less viscous lithospheric mantle, depending on the relative geometric mean viscosities of the two layers. When there is a low-viscosity shear zone beneath the fault, apparent viscosities are close to that of the shear zone immediately after the earthquake, although the apparent viscosities increase significantly during the later interseismic period. Inferences made from interseismic deformation that the lower crust is more viscous than the upper mantle may be entirely consistent with depth-dependent viscosity profiles that have a significant increase in viscosity from the lowermost crust to the uppermost mantle.

Evidence for tidal triggering of high-amplitude rapid tremor reversals and tremor streaks in northern Cascadia

We provide a new link between tectonic tremor propagation, tremor amplitude, and tidal stresses by analyzing high-resolution tremor locations and amplitudes determined by multibeam backprojection of data from an array of subarrays. For two Cascadia episodic tremor and slip events, we observe repeating, high-amplitude rapid tremor reversals (RTRs) and tremor streaks. They tend to occur when tremor amplitudes are highest and occur almost exclusively during periods of thrust-encouraging, tidally induced shear stress on the fault. We speculate that thrust-encouraging shear stress from tidal loading forces trigger RTRs and streaks that energetically rerupture the weakened fault behind the slow slip front. The high rate and amplitude of tremor during RTRs and streaks stands in contrast to the hypothesis that activity at the leading edge of the slow slip zone is the most energetic and loudest. This implies that the spatiotemportal pattern of slow earthquake slip migration is even more intricate than previously reported.

Slab tears and intermediate-depth seismicity

Active tectonic regions where plate boundaries transition from subduction to strike slip can take several forms, such as triple junctions, acute, and obtuse corners. Well-documented slab tears that are associated with high rates of intermediate-depth seismicity are considered here: Gibraltar arc, the southern and northern ends of the Lesser Antilles arc, and the northern end of Tonga trench. Seismicity at each of these locations occurs, at times, in the form of swarms or clusters, and various authors have proposed that each marks an active locus of tear propagation. The swarms and clusters start at the top of the slab below the asthenospheric wedge and extend 30–60km vertically downward within the slab. We propose that these swarms and clusters are generated by fluid-related embrittlement of mantle rocks. Focal mechanisms of these swarms generally fit the shear motion that is thought to be associated with the tearing process.

Scattered waves from low-frequency earthquakes and plate boundary structure in northern Cascadia

We use 3-D waveform modeling of LFEs (low-frequency earthquakes) to investigate their relation to plate boundary structure along a linear transect in northern Cascadia. To account for crustal velocity heterogeneity, a smoothed 3-D model of subduction zone structure is assembled that incorporates constraints from regional tomographic and plate boundary models. Scattered phases within LFE waveforms are identified based on synthetic predictions that incorporate thrust mechanisms aligned parallel to a dipping plate boundary atop a high-Vp/Vs low-velocity zone (LVZ). Scattering for near-vertical paths is dominated by S-to-P/S-to-S reflections/conversions from the LVZ. The modeling suggests that LFEs lie at or very close to the plate boundary and that the LVZ structure is laterally heterogeneous but broadly consistent with results from teleseismic analysis.

Low friction along the high slip patch of the 2011 Mw 9.0 Tohoku-Oki earthquake required from the wedge structure and extensional splay faults

We analyze the mechanical properties needed to account for the large shallow slip during the 2011 Tohoku-Oki earthquake and the activation of landward normal faulting within the forearc. We show that the morphology and internal structure of the forearc follows closely the prediction of the critical Coulomb wedge in horizontal compression, implying a high internal pore pressure ratio (λ=0.7+0.14/−0.48) and a low effective basal friction. We then show that the activation of the normal fault requires a lower effective basal friction beneath the outer wedge than beneath the inner wedge (μouter≤0.015), possibly due to transient dynamic weakening associated to the seismic rupture. Forearc normal faults could be considered as evidence for very efficient dynamic weakening along the megathrust and typify megathrust with high tsunamigenic potential.

A deep outer-rise reverse-fault earthquake immediately triggered a shallow normal-fault earthquake: The 7 December 2012 off-Sanriku earthquake (MW 7.3)

Teleseismic body wave analysis revealed that the 7 December 2012 off-Sanriku earthquake (MW 7.3) at the outer rise of Japan Trench consisted of two successive subevents. The first subevent with reverse-fault mechanism (Event 1, MW 7.1) at 56 km depth was followed by, approximately 20 s later, the second subevent with normal-fault mechanism (Event 2, MW 7.2) at 6 km depth. Finite-fault slip models show that the slip of Event 1 was concentrated around the initial rupture point with the maximum of 2.7 m and that Event 2 had two asperities with the maximum of 4.5 m at both sides of the initial rupture point. The static Coulomb Failure Function analyses suggested that Event 1 triggered Event 2 and that both subevents were promoted by the 2011 Tohoku earthquake (MW 9.1).

Stable, rapid rate of slip since inception of the San Jacinto fault, California

In California, where the San Jacinto fault (SJF) and San Andreas fault (SAF) accommodate the majority of the dextral shear deformation between the Pacific and North American plates, initiation of the SJF led to an apparent decline in the slip rate of the SAF. Previous studies suggest that since then, slip rate has covaried between these faults (possibly due to changes in fault strength, variation in topographic loading along a fault, or the development of new faults) and that presently the SJF is the dominant plate boundary structure. However, we dated displaced sedimentary deposits and landforms over three distinct time intervals since ~700ka, and our results imply a constant slip rate of 12.1+3.4/−2.6mm/yr. This rate is similar to the fault's lifetime rate and from rates derived from geodesy, suggesting that since the SJF initiated, its slip rate has remained relatively stable and does not exceed that of the SAF.

Interseismic coupling, stress evolution, and earthquake slip on the Sunda megathrust

The extent to which interseismic coupling controls the slip distribution of large megathrust earthquakes is unclear, with some authors proposing that it is the primary control and others suggesting that stress changes from previous earthquakes are of first-order importance. Here, we develop a detailed stress history of the Sunda megathrust, modified by coupling, and compare the correlation between slip and stress with that of slip versus coupling. We find that the slip distributions of recent earthquakes are more consistent with the stress field than with the coupling distributions but observe that in places, the stress pattern is strongly dependent on poorly constrained values of slip in historical earthquakes. We also find that of the 13 earthquakes in our study for which we have hypocentral locations, only two appear to have nucleated in areas of negative stress, and these locations correspond to large uncertainties in the slip distribution of pre-instrumental events.

Microslips as precursors of large slip events in the stick-slip dynamics of sheared granular layers: A discrete element model analysis

We investigate the stick-slip behavior of a granular system confined and sheared by deformable solid blocks using three-dimensional discrete element method simulations. Our modeling results show that large slip events are preceded by a sequence of small slip events—microslips—whose occurrence accelerates exponentially before the large slip event onset. Microslips exhibit energy release several orders of magnitude smaller than the large slip events. The microslip event rate is proposed as a measure of slip activity in the granular gouge layer. A statistical analysis shows that microslip event rate correlates well with large slip event onset and that variations in it can be used to predict large slip events. The emergence of microslips and their duration are found to be controlled by the value of the slipping contact ratio and are therefore related to the jamming/unjamming transition of frictional granular packings.

Convergence of the frequency-magnitude distribution of global earthquakes: Maybe in 200 years

study the ability to estimate the tail of the frequency-magnitude distribution of global earthquakes. While power-law scaling for small earthquakes is accepted by support of data, the tail remains speculative. In a recent study, Bell et al. (2013) claim that the frequency-magnitude distribution of global earthquakes converges to a tapered Pareto distribution. I show that this finding results from data fitting errors, namely from the biased maximum likelihood estimation of the corner magnitude θin strongly undersampled models. In particular, the estimation of θdepends solely on the few largest events in the catalog. Taking this into account, I compare various state-of-the-art models for the global frequency-magnitude distribution. After discarding undersampled models, the remaining ones, including the unbounded Gutenberg-Richter distribution, perform all equally well and are, therefore, indistinguishable. Convergence to a specific distribution, if it ever takes place, requires about 200 years homogeneous recording of global seismicity, at least.

Influences of temperature-dependent thermal conductivity on surface heat flow near major faults

We studied the thermomechanical effects on surface heat flow near major faults from positive feedback between temperature-dependent thermal conductivity k(T)∝ (1/T)b and frictional heating in a crust-lithosphere system using finite element simulations. Variable conductivity and frictional heating cause a drastic reduction in the thermal conductivity, and these changes can impact the heat flux. When b=1, the temperature is 400K higher around the fault than in the uniform conductivity case. This is caused by the reduction in thermal conductivity. In spite of the high temperature around the fault in the variable conductivity cases, the surface heat flux is 30% (for b=0.5) to 50% (for b=1) lower than in the uniform conductivity case. This thermal insulating effect may explain the lack of heat flow anomalies near major faults and is consistent with previous hypotheses about the nature of the shear strength associated with these faults.

Using core complex geometry to constrain fault strength

We present the first model results showing that some core complex detachment faults are strong and that their strength has to be in a narrow range to allow certain extensional structures to develop. The structures we simulate are kilometer-scale “rider blocks” that are particularly well observed on some oceanic core complexes as well as continental metamorphic core complexes. Previous numerical simulations of lithospheric extension produced the large-offset, core complex-forming, normal faults only when the faults were weaker than a given threshold. However, our new, high-resolution simulations indicate that rider blocks only result when the faults are stronger than a given level. A narrow range of fault weakening, relative to intact surrounding rock, allows for a consecutive series of rider blocks to emerge in a core complex-like geometry. Our results show that rider blocks develop when the dominant form of weakening is by reduction of fault cohesion while faults that weaken primarily by friction reduction do not form distinct rider blocks.

Magma dynamics feeding Yasur's explosive activity observed using thermal infrared remote sensing

A thermal infrared thermometer was used to record the passage of hot gases and fragments across a measurement area located at the exit of one of Yasur's active vents. Recording was completed over 2h during September 2011. A total of 200 explosive events were recorded. We define two types of event: low-energy events with typical thermal energies of 14kJ and high-energy events with typical thermal energies of 97kJ. Around 180 low-energy events were recorded, which together released 457kJ of radiant energy. In contrast, only 20 high-energy events were recorded, but they released 2042kJ. We suggest that low-energy events originate from a relatively shallow, degassed magma reservoir and are associated with bursting of bubbles formed by bubble coalescence during ascent. Instead, high-energy events originate from a relatively deep, fresh magma reservoir and are associated with slugs formed by foam collapse.

Cost-effective monitoring of ground motion related to earthquakes, landslides, or volcanic activity by joint use of a single-frequency GPS and a MEMS accelerometer

Real-time detection and precise estimation of strong ground motion are crucial for rapid assessment and early warning of geohazards such as earthquakes, landslides, and volcanic activity. This challenging task can be accomplished by combining GPS and accelerometer measurements because of their complementary capabilities to resolve broadband ground motion signals. However, for implementing an operational monitoring network of such joint measurement systems, cost-effective techniques need to be developed and rigorously tested. We propose a new approach for joint processing of single-frequency GPS and MEMS (microelectromechanical systems) accelerometer data in real time. To demonstrate the performance of our method, we describe results from outdoor experiments under controlled conditions. For validation, we analyzed dual-frequency GPS data and images recorded by a video camera. The results of the different sensors agree very well, suggesting that real-time broadband information of ground motion can be provided by using single-frequency GPS and MEMS accelerometers.