Director's Report

Background and Facilities

The Berkeley Seismological Laboratory (BSL), formerly the Berkeley Seismographic Station (BSS), is the oldest Organized Research Unit (ORU) on the U. C. Berkeley campus. Its mission is unique in that, in addition to research and education in seismology and earthquake-related science, it is responsible for providing timely information on earthquakes (particularly those that occur in northern and central California) to the UC Berkeley constituency, the general public, and various local and state government and private organizations. The BSL is therefore both a research center and a facility/data resource, which sets it apart from most other ORUs. A major component of our activities is focused on developing and maintaining several regional observational networks, and participating, along with other agencies, in various aspects of the collection, analysis, archival and distribution of data pertaining to earthquakes, while maintaining a vigorous research program on earthquake processes and Earth structure. In addition, the BSL staff spends considerable time with public relations activities, including tours, talks to public groups, responding to public enquiries about earthquakes and, more recently, World-Wide-Web presence (http://seismo.berkeley.edu/).

U.C. Berkeley installed the first seismograph in the Western Hemisphere at Mount Hamilton (MHC) in 1887. Since then, it has played a leading role in the operation of state-of-the-art seismic instruments and in the development of advanced methods for seismic data analysis and interpretation. Notably, the installation, starting in 1927, of Wood-Anderson seismographs at 4 locations in northern California (BKS, ARC, MIN and MHC) allowed the accurate determination of local earthquake magnitude ($M_L$) from which a unique historical catalog of regional earthquakes has been maintained to this day, providing crucial input to earthquake probabilities studies.

Over the years, the BSS continued to keep apace of technological improvements. The first centrally telemetered network using phone lines in an active seismic region was installed by BSS in 1960. The BSS was the first institution in California to operate a 3-component "broadband" system (1963). Notably, the BSS played a major role in the early characterization of earthquake sources using "moment tensors" and source-time functions, and made important contributions to the early definitions of detection/discrimination of underground nuclear tests and to earthquake hazards work, jointly with UCB Engineering. Starting in 1986, the BSS acquired 4 state-of-the-art broadband instruments (STS-1), while simultaneously developing PC-based digital telemetry, albeit with limited resources. As the telecommunication and computer technology made rapid progress, in parallel with broadband instrument development, paper record reading could be completely abandoned in favor of largely automated digital data analysis.

The current modern facilities of BSL have been progressively built over the last 13 years, initiated by significant "upgrade" funding from U.C. Berkeley in 1991-1995. The BSL currently operates and acquires data, continuously and in real-time, from over 60 regional observatories, housing a combination of broadband and strong motion seismic instrumentation installed in vaults, borehole seismic instrumentation, permanent GPS stations of the BARD network, and electromagnetic instrumentation. The seismic data are fed into the BSL real-time processing and analysis system and are used in conjunction with data from the USGS NCSN network in the joint earthquake notification program for northern California, started in 1996. This program capitalizes on the complementary capabilities of the networks operated by each institution to provide rapid and reliable information on the location, size and other relevant source parameters of regional earthquakes. In recent years, a major emphasis in BSL instrumentation has been in densifying the state-of-the-art seismic and geodetic networks, while a major on-going emphasis in research has been the development of robust methods for quasi-real time automatic determination of earthquake source parameters and predicted strong ground motion, using a sparse network combining broadband and strong motion seismic sensors, as well as permanent geodetic GPS receivers.

The backbone of the BSL operations is a regional network of 25+ digital broadband and strong motion seismic stations, the Berkeley Digital Seismic Network (BDSN), with continuous telemetry to UC Berkeley. This network provides the basic regional data for the real-time estimation of location, size and rupture parameters for earthquakes of M 3 and larger in central and northern California, within our Rapid Earthquake Data Integration (REDI) program and is the Berkeley contribution to the California Integrated Seismic Network (CISN). It also provides a fundamental database for the investigation of three-dimensional crustal structure and its effects on regional seismic wave propagation, ultimately crucial for estimating ground shaking for future earthquakes. Most stations also record auxiliary temperature/pressure channels, valuable in particular for background noise quality control. Complementing this network is a 25 station "high-resolution" network of borehole seismic sensors located along the Hayward Fault (HFN) and under the Bay Area bridges, operated jointly with the USGS/Menlo Park and linked to the Bridge Safety Project of the California Department of Transportation (Caltrans). The latter has facilitated the installation of sensor packages at 15 bedrock boreholes along 5 east-bay bridges in collaboration with LLNL. A major science goal of this network is to collect high signal-to-noise data for micro-earthquakes along the Hayward Fault to gain insight into the physics that govern fault rupture and its nucleation. The BSL is also involved in the operation and maintenance of the 13 element Parkfield borehole seismic array (HRSN), which is yielding enlightening results on quasi-periodic behavior of micro-earthquake clusters and important new constraints on earthquake scaling laws and is currently playing an important role in the characterization of the site for the future San Andreas Fault Observatory at Depth (SAFOD). Since April 2002, the BSL is also involved in the operation of a permanent broadband ocean bottom station, MOBB, in collaboration with MBARI (Monterey Bay Aquarium Research Institute).

In addition to the seismic networks, the BSL is involved in data archival and distribution for the permanent geodetic BARD (Bay Area Regional Deformation) Network as well as the operation and maintenance, and data processing of 22 out of its 70+ sites. Whenever possible, BARD sites are collocated with BDSN sites in order to minimize telemetry costs. In particular, the development of analysis methods combining the seismic and geodetic data for the rapid estimation of source parameters of significant earthquakes has been one focus of BSL research.

Finally, two of the BDSN stations (PKD, SAO) also share data acquisition and telemetry with 5-component electromagnetic sensors installed with the goal of investigating the possibility of detection of tectonic signals.

Archival and distribution of data from these and other regional networks is performed at the Northern California Earthquake Data Center (NCEDC), operated at the BSL in collaboration with USGS/Menlo Park. The data reside on a mass-storage device (2.5+ Terabyte capacity), and are accessible "on-line" over the Internet (http://www.quake.geo.berkeley.edu). Among others, data from the USGS Northern California Seismic Network (NCSN), are archived and distributed through the NCEDC. The NCEDC also maintains, archives and distributes the ANSS/CNSS earthquake catalog.

Core University funding to our ORU has suffered from permanent budget cuts to research programs from the State of California, and currently provides salary support for 2 field engineers, one computer expert, 2 data analysts, 1 staff scientist and 2 administrative staff. This supports a diminishing portion of the operations of the BDSN and provides seed funding for our other activities. All other programs are supported through extra-mural grants primarily from the USGS and NSF, and in the past two years, the Governor's Office of Emergency Services (OES). We acknowledge valuable recent contributions from other sources such as Caltrans, the CLC program, PEER, as well as our Earthquake Research Affiliates.

Highlights of 2002-2003

Infrastructure and Earthquake
Notification

In 2002-2003, the BSL has continued its involvement in several major projects, including the CISN, and the installation and operation of Mini-PBO instrumentation. We have also taken initial steps in preparation of our involvement in the deployment in California of the BigFoot component of USArray/Earthscope.

We are entering the 3rd year of our participation in the efforts of the CISN, for which we received support in 2002-2003 from the State of California through the Office of Emergency Services (OES) (Chapter 2).

The main goal of the CISN is to ensure a more uniform system for earthquake monitoring and reporting in California. The highest priority, from the point of view of emergency responders in California, is to improve the robustness of statewide real-time notification and to achieve a uniform interface across the State to the California OES and other emergency responders. This represents a major challenge, as the CISN started as a heterogeneous collection of networks with disparate instrumentation, software systems and culture. Therefore, in the past year, the emphasis has been on software development for seamless data exchange between institutions, the establishment of redundant links to data sources, as well as the construction of a single interface to access the different products, such as earthquake locations, magnitudes and, most importantly "ShakeMaps".

Another goal of the CISN program is to improve the seismic infrastructure in northern California. Because funding is limited, this goal is currently pursued at a slower pace. Nevertheless, two new broadband/strong motion stations have been installed in 2002-2003, and three additional sites have been selected and permitted. They are currently at different stages of completion. The CISN has held its first Northern California outreach workshop on "ShakeMaps" in January 2003, with BSL participation, and has been actively engaged in working with its Advisory Committee towards meeting the needs of the users, among which Caltrans as well as utilities companies.

BSL staff spend considerable efforts in organizational activities for CISN, notably by participating in the CISN Project Management Group (Gee), which includes weekly 2 hour phone conferences, and the Standards Committee (Neuhauser-chair, Gee, Lombard), which strives to define and coordinate software development tasks. Romanowicz and Gee serve on the CISN Steering Committee, which was chaired by Romanowicz in 2001. The CISN also represents California as a designated region of ANSS (Advanced National Seismic System) and the BSL is actively involved in planning activities for the ANSS.

This past year has seen progress in the installation efforts of the Mini-PBO project (Chapter 8), a project supported partly by a grant from the NSF/MRI program, in collaboration with CIW, UCSD and USGS/Menlo Park, with matching from participating institutions (including UCB) as well as Caltrans (http://seismo.berkeley.edu/bdsn/mpbo_overview.html). This project's focus is the installation of a network of multi-parameter stations in the San Francisco Bay Area to monitor the evolution of tectonic strain in time and space - a pilot project for the Plate Boundary Observatory (PBO) component of Earthscope (a national infrastructure program funded by NSF within its Major Research Equipment program). Mini-PBO instrumentation comprises 3 component borehole strainmeters and seismometers, GPS receivers and auxiliary sensors (such as pore pressure, temperature, and tilt). The data are telemetered to UC Berkeley and distributed through the NCEDC. Five holes have now been drilled and instrumented with considerable involvement of BSL staff (Murray, Basset, W. Johnson, Karavas, Friday, Rapkin, Thomas). The initial goal of 10 stations has been reduced to 6 due to budgetary constraints and delays related to considerable difficulties and cost-overruns in drilling. We are still hoping that the 6th and last hole will be drilled with Caltrans's help, as a "hole of opportunity", in 03-04. Meanwhile, all existing 5 stations now have borehole strainmeters and seismometers, as well as tiltmeters. Two sites are completed, while the remaining three are in the final stages of the installation of GPS receivers, Quanterra data loggers and/or power and communications systems.

The MOBB (Monterey Ocean bottom Broad Band observatory) is a collaborative project between the BSL and MBARI and builds upon the experience gained in 1997 through the MOISE project, which involved the temporary deployment of a broadband ocean bottom system in Monterey Bay. MOBB is now a permanent installation and comprises a broadband seismic package (Guralp CMG-1), a battery and recording package, as well as auxiliary sensors: a current-meter and a DPG (differential Pressure Gauge). The system was assembled and tested at BSL in early 2002, and successfully deployed in April 2002 (Chapter 3). In particular, extensive testing and seismometer insulation procedures, which were developed at Byerly Vault on the UCB campus prior to MOBB deployment (Chapter 9) have now been applied to three similar systems destined for the KECK project (Juan de Fuca plate), in collaboration with University of Washington at Seattle. There have been 4 dives in 2002-2003 to recover and exchange battery packages and recording systems from the seafloor. Software problems have unfortunately led to the loss of much data during the first part of 2003. We will know after the next dive, scheduled for 09/15/03, whether these problems have definitely been fixed.

In the past year, the BSL has continued to be involved in the coordination of site characterization for the SAFOD drilling project (another component of Earthscope) in the Parkfield area (Chapter 5). A new central data acquisition system with near real time transmission to Berkeley of event data and waveform samples allows routine checks of quality of operation, and more timely response to failures and sources of noise. The resulting dataset is of primary importance for monitoring the evolution of microseismicity, particularly in the SAFOD drilling zone, where the new triggering scheme allows detection of events down to magnitude -1.0, a three-fold higher detection rate compared to the local surface seismic network, in a 30 km stretch around the M6 earthquake of 1966.

Other accomplishments in the past year include the completion of a new BDSN station (HUMO - Chapter 3) in southern Oregon, in collaboration with USGS/NSN and IRIS programs, and, as mentioned previously in the framework of CISN, the installation of two new broadband stations.

The NHFN network project has seen the upgrade of infrastructure at 7 stations on the Bay Bridge (Chapter 4), in anticipation of the deployment of the Quanterra recording systems and associated telemetry to UC Berkeley. Stations BBEB and W02B are now online, and the remaining five sites will be brought up this fall. In parallel, we have been working on improvement of data processing techniques. The datastreams from the borehole seismometers of the Mini-PBO project are progressively being integrated with those of the NHFN (Chapter 8).

On the NCEDC front (Chapter 11), we continue archiving and distribution on-line of data from expanding BDSN, NHFN, HRSN, BARD, Mini-PBO, and other networks and data collections in northern California and Nevada. There has been progress in the construction of the "metadata" for the NCSN and a major "revamping" of the NCEDC Webpage. The NCEDC is participating in the UNAVCO-sponsored GPS Seamless Archive Centers (GSAC) initiative, which is developing common protocols and interfaces for the exchange and distribution of continuous and survey-mode GPS data, and is now both a primary provider for BARD/BSL data, a wholesale collection point for other northern California GPS data, and a retail center for all GSAC data.

The BSL continues to collaborate with the USGS/Menlo Park in the generation of ShakeMap for northern California and has been developing and implementing successive upgrades to this system, integrated within the REDI environment (Chapter 10). ShakeMap is calculated routinely for magnitude 3.5 and larger events in northern California. Any magnitude 5.0 or larger will now also trigger the finite-fault processing. In 2002-2003, a 2nd ShakeMap system has been installed at UC Berkeley, to provide redundancy for northern California earthquakes. Also in the past year, we have implemented a database within the real-time system and have been involved in redesigning the Northern California operations, to achieve a single system at USGS/Menlo Park and UCB.

Finally, we have been routinely monitoring electric and magnetic field at two of our observatories since 1995. In 2002-2003, efforts in this direction have been stepped up: an automated quality control software has been implemented and a time domain processing software is currently being developed and perfected (Chapter 6).

In 03-04, a major new component of our activities will be coordinating with IRIS on the deployment in northern California of $ 50$ temporary broadband stations of the BigFoot array of Earthscope. The BSL will contribute many (15+) of its existing sites to this effort. Likewise, we anticipate helping out with some aspects of the Plate Boundary Observatory component of Earthscope. In particular, we have received funding from NSF for the support of routine operations of the BARD GPS network for the next 1.5 years, as part of a collaborative proposal coordinated by UNAVCO Inc. We will be actively engaged in the next year in planning the integration of existing permanent GPS networks into the PBO.

Research Accomplishments

Chapter III documents the main research contributions of the past year. Research at the BSL spans a broad range of topics, from the study of microseismicity at the local scale to global deep earth structure, and includes seismological, geodetic and remote sensing (InSAR) techniques.

In the general area of earthquake source studies, a major earthquake (M 7.9) occurred in Alaska on the Denali Fault on 11/03/2002. This has been an opportunity for Professor Dreger and collaborators to combine his broadband waveform source tomography approach with GPS and surface displacement observations to study the complex fault geometry of this unusual event, documenting in particular evidence for discontinuous rupture propagations (III.1). Professor Dreger and graduate students Wucheng Chi (III.2), Dennise Templeton (III.9) and Gilead Wurman (III.7), as well as undergraduate student Sarah Minson (III.10) have pursued the study of various earthquake source problems in California, Taiwan, and Japan, in particular with a continued interest in the characterization of earthquakes related to fluid migrations in volcanic areas. Graduate student David Dolenc is using microtremors to illuminate basin structure in the San Francisco Bay Area to anticipate ground motions in large earthquakes (III.8), while Dr. Robert Uhrhammer has continued his efforts to characterize historical seismicity in the San Francisco Bay Area (III.3) as well as Northern California (III.4). Dr. Robert Nadeau continues to discover and analyze new sequences of micro-earthquakes at Parkfield (III.5) in an effort to better understand how the fault works. In particular, he has documented evidence for periodic pulsing along the central San Andreas Fault between Parkfield and the southern end of the Loma Prieta earthquakes. In collaboration with Dr. Nadeau and Professor Bürgmann, post-doctoral associate Frédérique Rolandone has been studying the time variations of the maximum depth of seismicity around major earthquakes during the earthquake cycle (III.6). With graduate student David Dolenc, we have started to analyze the background noise at the ocean bottom MOBB site with the goal of a-posteriori noise reduction using correlations with current, pressure and other auxiliary data (III.11). Dr. Peggy Hellweg has completed the installation and testing of our automated moment tensor inversion codes at the Center for Monitoring Research, in the framework of efforts to monitor the CTBT (III.13). With graduate student Junkee Rhie, we are perfecting a very low frequency event detection method, with the ultimate goal of trying to characterize sources of the continuous background excitation of earth's free oscillations (III.12).

The BSL has also been actively involved in studying active deformation using various geodetic techniques. Working with Professor Roland Bürgmann, graduate students Matt d'Alessio and Ingrid Johanson have been analyzing campaign GPS data and InSAR to monitor fault slip and strain accumulation in the San Francisco Bay region, characterizing creep events and delineating rigidly behaving crustal blocks (III.14,III.16). Studies of strain accumulation and distribution have also been pursued by Dr. Mark Murray in northern California (III.15) and the New Madrid Seismic Zone (III.18), while post-doctoral associate Maurizio Battaglia documented the existence of a microplate in the Adriatic region (III.19). Finally, Dr. Andy Freed used GPS data to characterize the nature of viscous flow associated with the coupled 1992 Landers and 1999 Hector Mine earthquakes (III.17).

With graduate students Yuancheng Gung, Mark Panning, Akiko To, Sébastien Rousset and post-doctoral Miller fellow Yann Capdeville, Professor Romanowicz has been pursuing various aspects of wave propagation in the 3D spherical earth, adapting the coupled Spectral Element/normal mode method to study complex structure at the base of the mantle (III.20, III.23), experimenting with a neighborhood algorithm to explore the range of possible large scale variations in density in the mantle using normal mode observations (III.25) and implementing anisotropic parameterization in global mantle tomography (III.21, III.22). With graduate student Aimin Cao, Romanowicz has pursued the study of core structure, revisiting this past Spring the issue of the density jump at the Inner Core Boundary (III.24). Also included in this report is a contribution from graduate student David Stegman, working with Professor Mark Richards on a model of convection of the moon (III.26) featured this year on the cover of our Annual Report.

We are proud to note that Yuancheng Gung, Wuchen Chi and David Stegman successfully completed their Ph.D.'s in the summer of 2003, and will pursue post-doctoral appointments at BSL, Caltech and Canberra, Australia, respectively. Last but not least, post-doctoral fellow Andy Freed left last Fall to take a faculty position at Purdue University, while Miller Fellow Yann Capdeville went back to Paris, France at the end of August to join the research staff at the CNRS.

Acknowledgements

I wish to thank our technical and administrative staff, scientists and students for their efforts throughout the year and their contributions to this annual report. Individual contributions to activities and report preparation are mentioned in the corresponding sections, except for the Appendix section, prepared by Christina Jordan and Eleanor Blair.

Starting July 1st, 2002, Professor Douglas Dreger has been appointed Associate Director of the BSL. In particular, Doug has assumed overall responsibility, with help from Bob Nadeau, for the HRSN and NHFN programs, following Professor McEvilly's death.

I also wish to specially thank the individuals who have regularly contributed to the smooth operation of the BSL facilities: André Basset, Sierra Boyd, Rich Clymer, Doug Dreger, John Friday, Lind Gee, Wade Johnson, Bill Karavas, Pete Lombard, Rick McKenzie, Mark Murray, Bob Nadeau, Doug Neuhauser, Charley Paffenbarger, David Rapkin, Cathy Thomas, Bob Uhrhammer, and Stephane Zuzlewski. To our regret, Cathy Thomas went back home to the East Coast in March 2003.

In 2002-2003, there have been some changes in the BSL administrative office. Eleanor Blair, and Christina Jordan continue to provide critical support to the administration of our lab, but Heather Reed left in 11/2002. We welcome Myriam Cotton, who joined the administrative office in 11/2002, helping with accounting. They are assisted by part-time student employees Morgan Weibel, Patty Villa and Loan Pham.

I also wish to thank our undergraduate assistants Tom Fournier, Alex Goines, Lisa Krain, Edwin Kwan, Sarah Minson, and Gabriel Treves, for their contributions to our research and operational activities. Lisa left in December 2002 to follow her newly acquired husband and pursue graduate studies in southern California, and Sarah left in August 2003, to become a graduate student in Geophysics at Caltech.

As every year, I am particularly thankful to Lind Gee and Christina Jordan for their help in putting together this Annual Report.

The Annual Report of the Berkeley Seismological Laboratory is available on the WWW at http://seismo.berkeley.edu/annual_report/.




Barbara Romanowicz

Sept 15, 2003

Glossary of Common Acronyms

Table 1.1: Standard abbreviations used in this report.
Table: continued
Acronym Definition
   
AGU American Geophysical Union
ANSS Advanced National Seismic System
BARD Bay Area Regional Deformation
BDSN Berkeley Digital Seismic Network
BSL Berkeley Seismological Laboratory
BSS Berkeley Seismographic Station
CISN California Integrated Seismic Network
CGS California Geological Survey
CLC Campus Laboratory Collaboration
CNSS Council of the National Seismic System
EM Electromagnetic
EPRI Electric Power Research Institute
FBA Force Balance Accelerometer
FIR Finite Impulse Response
FRAD Frame Relay Access Device
GPS Global Positioning System
HFN Hayward Fault Network
HRSN High Resolution Seismic Network
IGS International Geodetic Service
IMS International Monitoring System
InSAR Interferometric Synthetic Aperture Radar
IRIS Incorporated Research Institutions for Seismology
ISC International Seismological Center
ISTAT Integrating Science, Teaching, and Technology
JPL Jet Propulsion Laboratory
LBNL Lawrence Berkeley National Laboratory
LLNL Lawrence Livermore National Laboratory
MBARI Monterey Bay Aquarium Research Institute
MHH Murdock, Hutt, and Halbert
MOBB Monterey Ocean Bottom Broadband observatory
MOISE Monterey Bay Ocean Bottom International Seismic Experiment
MPBO Mini-Plate Boundary Observatory
MRI Major Research Initiative
MRE Major Research Equipment
MT Magnetotelluric
NCEDC Northern California Earthquake Data Center
NCSN Northern California Seismic Network
NEHRP National Earthquake Hazards Reduction Program
NEIC National Earthquake Information Center
NHFN Northern Hayward Fault Network
NGS National Geodetic Survey
NSF National Science Foundation
NSN National Seismic Network
OES Office of Emergency Services
ORU Organized Research Unit
PBO Plate Boundary Observatory
PEER Pacific Earthquake Engineering Center
PH Pilot Hole
PPE Parkfield Prediction Experiment
PREM Preliminary Reference Earth Model
PSD Power Spectral Density
REDI Rapid Earthquake Data Integration
SAF San Andreas Fault
SAFOD San Andreas Fault Observatory at Depth
SAR Synthetic Aperture Radar
SCEC Southern California Earthquake Center
SCEDC Southern California Earthquake Data Center
SCIGN Southern California Integrated GPS Network
SEED Standard for the Exchange of Earthquake Data
SEM Spectral Element Method
SHFN Southern Hayward Fault Network
SIO Scripps Institutions of Oceanography
SNCL Station Network Channel Location
SSA Seismological Society of America
STP Seismogram Transfer Program
UCB University of California at Berkeley
UNAVCO University NAVSTAR Consortium
UrEDAS Urgent Earthquake Detection and Alarm System
USGS United States Geological Survey

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