The Berkeley Seismological Laboratory (BSL) is an Organized Research Unit (ORU) of the University of California at Berkeley, whose mission, since the 1930's, has been to conduct research and train students in seismology, as well as provide timely information and education on earthquakes in central and northern California to the University, local and state government and the public. This latter specific mission sets the BSL apart from other ORUs, in that a major component of our activities is focused on developing and maintaining several regional observational networks, and participating, along with other agencies at the State, National and International level, in various aspects of the collection, analysis, archival and distribution of data pertaining to earthquakes, while maintaining a vigorous research program on earthquake processes as well as Earth's structure.
Notably, following 15 years of parallel operations, the BSL and the US Geological Survey at Menlo Park have, since 1996, combined efforts in a joint Earthquake Notification Program for northern California, which 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 instrumentation at the BSL has been in densifying the state of the art seismic and geodetic networks that we operate, 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 20+ 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. 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 10+ station "high-resolution" network of borehole seismic sensors along the Hayward Fault (HFN), operated jointly with the USGS/Menlo Park and linked to the Bridge Safety Project of the California Department of Transportation, which has made possible the installation of sensor packages at 15 bedrock boreholes at 5 east-bay bridges in collaboration with LLNL. A major basic science goal of this network is to collect high signal-to-noise data for microearthquakes along the Hayward Fault in order 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 Parkfield borehole seismic array, which is yielding enlightening results on quasi-periodic behavior of microearthquake clusters and important new constraints on earthquake scaling laws.
In addition to the seismic networks, 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 19 out of its 45-or-so 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 also share data acquisition and telemetry with 5-component electro-magnetic 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. 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 CNSS earthquake catalog.
Core University funding to our ORU provides salary support for 3 field engineers, one computer expert, 2 data analysts, 1 staff scientist and 2 administrative staff. This covers the basic needs of the operations of the BDSN and seed funding for our other activities. All other programs are supported through a combination of extra-mural grants primarily from the USGS and NSF. We acknowledge valuable recent contributions from other sources such as the OES, Caltrans, the CLC program, PEER as well as our Earthquake Research Affiliates.
This past year has been marked by intense involvement of BSL members in the development of a Strategic Plan and an Implementation Plan for the CISN (California Integrated Seismic Network), in view of significant new support in FY'02 from the State of California through the Office of Emergency Services. This has been effected in particular through the participation in the CISN Steering Committee (Romanowicz-chair, Gee), the Project Management Group (Gee) and the Standards Committee (Neuhauser-chair, Gee).
A major goal of the CISN is to ensure a more uniform system for earthquake monitoring in California, through the improvement of seismic infrastructure in northern California and continued maintenance of the TriNet system in southern California. Another major goal is to integrate the earthquake monitoring and reporting efforts in the State, using compatible software and creating a single catalog. In particular, we will work to improve the robustness of statewide rapid notification and work with the California OES and other emergency responders to maximize the use and benefit of this real time seismic information.
With the new support from the State of California, in the coming year, the BSL will be involved in consolidating the USGS/UCB joint notification system in northern California (i.e. more completely merging the systems now in operation at each institution) as well as in the installation of several new broadband stations.
The CISN also represents California as a designated region of USGS's ANSS (Advanced National Seismic System) and several members of our staff (McEvilly, Gee, Neuhauser) have dedicated much of their time towards the design of an Implementation Plan for the ANSS.
In the past year, under Doug Dreger's leadership, the BSL has participated in the preparation of another successful proposal to the State of California, CITRIS (Center for Information Technology Research in the Interest of Society) to the State of California, contributing to the section on natural hazard mitigation.
The "mini-PBO" project (Chapter 7), in collaboration with CIW, UCSD and USGS/Menlo Park, is getting off the ground. This project's focus is the installation of approximately 10 multi-parameter stations in the San Francisco Bay Area to monitor the evolution of tectonic strain in time and space. Instrumentation comprises borehole strainmeters and seismometers, GPS receivers and auxiliary sensors (pore pressure, temperature...). The data will be telemetered to UC Berkeley and distributed through the NCEDC. The first two holes were drilled in early summer 2001 and are awaiting electronics, recording systems, and the installation of GPS receivers, which will be mounted on the casing of the borehole in an experimental monument design proposed by BSL staff (Murray, Karavas). The first data should be available in early October 2001. Three additional holes will be drilled and instrumented before the end of 2001.
In the past year, the BSL has also expanded its monitoring infrastructure in the Parkfield area (Chapter 4), in preparation for the NSF SAFOD drilling project. Three new borehole seismic stations have been installed at the north- western end of the current HRSN network. In addition, a new 24-bit data acquisition system with a frame-relay connection to UCB is now operational, allowing near real-time centralized remote triggering as well as remote access to the borehole network for data quality control. A new earthquake triggering scheme has been designed and is also used for joint triggering of the 60 station PASSCAL surface broadband deployment.
Other accomplishments in the past year include the deployment of two new BDSN stations (JCC, RFSB, Chapter 2), the search and permitting of a site in southern Oregon to become a joint BDSN/GSN/NSN broadband seismic station, and the completion of GPS data acquisition through the Quanterra data loggers at 12 BARD sites collocated with BDSN stations (Chapter 3). This allows for local storage of GPS data in case of telemetry outages, improving the robustness of data acquisition.
In addition, a major effort has gone into the development of a broadband sensor testing facility (Chapter 8, Uhrhammer, Friday, McEvilly), including the construction of a shake table, which has served for the characterization of 8 different sensors for the IRIS Instrumentation Committee, as well as for the testing of BDSN broadband and strong motion sensors.
On the NCEDC front (Chapter 10), a major accomplishment has been the collaboration with Will Prescott and colleagues at USGS/Menlo Park, to document, archive and make accessible to the geophysical community a large dataset of low-frequency geophysical data collected at the USGS for the past 25 years. This includes over 1300 channels of tilt, tensor and dilatation strainmeter, creep, magnetic field, water level, temperature, pore-pressure, rain and snow accumulation as well as wind-speed data. The archive is now active and updated daily.
Finally, the quasi real-time finite-fault inversion package developed by Doug Dreger and Asya Kaverina has been migrated to the REDI operational environment (Chapter 9), and the results are integrated in the generation of ShakeMap for northern California (an effort lead by USGS Menlo Park). ShakeMap, which has been integrated into REDI environment is now 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.
Chapter III describes the main research contributions of the last year. As in previous years, our research activities span a broad array of topics, with local, regional or global focus. At the local/regional levels, this includes studies of regional deformation using GPS and InSAR (12.1, 12.2), seismicity studies at the micro- and macroscopic levels to improve our understanding of fault zone processes (12.3, 12.4, 12.6, 12.7), modelling of earthquake source ruptures (12.8, 12.10), modelling of regional wave propagation and the effects of basin structure on observed ground shaking (12.9), improvement of moment tensor inversion techniques (12.11, 12.12). Some of the highlights include the development of a new method to measure heat generated during earthquakes using fission track thermochronology, with application to historical seismicity (12.5), and the discovery of coherent pulsing episodes in slip-rate along portions of the San Andreas Fault, based on microearthquake clustering observations (12.4).
At the global scale, research projects focused on three-dimensional structure span from the upper mantle to the inner core, using either tomographic techniques (12.16,12.17,12.18,12.20) or forward modelling approaches (12.14,12.15,12.19). Preliminary tests of a new methodology for studying mantle plumes are proposed, based on time-domain electrical conductivity measurements (12.13). Highlights include the development of a new 3D Q model of the upper mantle (12.16), completion of a model of P velocity in D" based on PKP and PcP data (12.20) and the adaptation to the case of D" of the coupled spectral elements/normal mode method (12.15).
I wish to thank our technical and administrative staff, scientists and students for 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.
I also wish to specially thank the individuals who regularly contribute to the smooth operation of the BSL facilities: André Basset, Rich Clymer, Doug Dreger, John Friday, Lind Gee, Wade Johnson, Bill Karavas, Pete Lombard, Tom McEvilly, Rick McKenzie, Mark Murray, Bob Nadeau, Doug Neuhauser, Charley Paffenbarger, David Rapkin, Bob Uhrhammer, and Stephane Zuzlewski. Fumiko Tajima initiated negotiations for and facilitated the installation of the Japanese UReDAS seismic early warning system at BSL in experimental mode.
Eleanor Blair and Christina Jordan continue to provide invaluable support to the administration of our lab, with help from Bari Burton, Natalie Champ, Keia Shipp, and Morgan Weibel. Conditions have been particularly stressful due to the introduction of the BFS, a shortage of personnel in the office, and the fact that Bari Burton, whose family had moved to Antioch, left us in March. We thank her for her help with accounting for the BSL and wish her all the best. BSL administrative office has also been providing training for the EPS department administrative personnel, in a period of transition in that office. We are also grateful to Ruth Saha, who helped out during several periods of high demand.
In 2000-2001, there have been some changes in BSL personnel. Steve Fulton traded his responsibilities in data quality control for a software development position at the SSL while Asya Kaverina has gone on to pursue a career in financial securities trading. André Basset replaced Ray Baxter to assist Mark Murray with GPS related work. Pete Lombard joined the BSL to help with software development related to the joint UCB/USGS notification program and Heather Read recently joined our administrative office to carry on the accounting tasks in replacement of Bari. We also have welcomed Yann Capdeville, Miller fellow collaborating with B. Romanowicz, and more recently, post-doc Peggy Hellweg, who has replaced Geoff Clitheroe at the end of June 2001, in the task of porting our real-time moment tensor software to the PIDC under our DTRA funded project.
I also wish to thank our undergraduate assistants A. Antriasian, S. Araki, R. Brito, S. Chu, T. Fournier, L. Krain, A. Newman, S. Romero Ramirez, K. Spiller, G. Treves, and B. Vessali for their contributions to our research and operational activities. I am particularly thankful to Lind Gee and Christina Jordan for their help in putting together this Annual Report. Finally, I wish to thank Tom McEvilly for his role as acting Director during the period 02/01/01-04/30/01, while I was away on sabbatical leave.
The Annual Report of the Berkeley Seismological Laboratory is available on the WWW at //www.seismo.berkeley.edu/seismo/annual_report/.
Sept 23, 2001