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 and tectonics.
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/MP 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, after 15 years of intense data collection and processing, is now 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 heavily involved in data archival and distribution for the permanent geodetic BARD network (Bay Area Regional Deformation Array) 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 through the Northern California Earthquake Data Center (NCEDC), operated at the BSL in collaboration with USGS/MP. The data reside on a mass-storage device, recently upgraded to 2.5 Terrabyte capacity, and are accessible "on-line" over the Internet. Among others, data from the USGS Northern California Seismic Network (NCSN), since its deployment in 1984, 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 Program.
This year has been marked by one crucial event: last winter, U.C. Berkeley undertook a major review of its Organized Research Units. I am delighted to announce that the BSL has been approved for continuation for the next 15 years, beginning on 01/01/2001. We were congratulated by Vice Chancellor Joseph Cerny for being an extremely productive ORU and the review panel has described it, in particular, as "an important and highly visible asset to the campus in terms of the intellectual activity it generates, the significant role it plays with state and federal agencies and the wide recognition it enjoys with the general public". Campus support is crucial to our program and will help us pursue our efforts on a solid basis.
Another important event of the past year is the creation of the CISN (California Integrated Seismic Network) in which the BSL is joining efforts with other institutions involved in earthquake monitoring in California towards coordinating regional network deployment, data acquisition in real time and release of information about earthquakes, as well as data archiving and distribution (Section 9.4). The BSL is a founding member of the CISN along with USGS/Menlo Park, CDMG, USGS/Pasadena and Caltech, and as such has two representatives on the CISN Steering Committee (currently: Barbara Romanowicz (chair) and Lind Gee). The CISN organization will merge the efforts of TriNet in southern California and TriNet-North, which was initiated in the last two years in northern California. We have been actively involved in designing the charter of the CISN, and in the work of several working groups, notably the crucial "Standards" group (BSL representatives Doug Neuhauser, chair and Lind Gee) which has the goal of designing the required software interfaces that will allow seamless data exchange between the different groups involved in the CISN. Another active group is involved in coordinating the efforts in northern and southern California towards the production of real-time "Shake-Maps", with the active participation of Doug Dreger, representing the BSL.
The BSL faculty and research staff are also actively involved in the preparation of several other major US instrumentation initiatives, namely the ANSS (Advanced National Seismic System) of the USGS, and the USArray, SAFOD and PBO programs, which are part of Earthscope. In preparation for PBO, a pilot collaborative project (casually referred to as "mini-PBO") has been funded by the MRI program of NSF, with matching funds from the participating institutions (UC Berkeley, Carnegie Inst. of Washington, UC San Diego, USGS/MP). A focus is to install 10 multiparameter stations in the San Francisco Bay Area, involving borehole strainmeters and seismometers as well as permanent GPS receivers, and another 9 GPS stations covering the gap between the SCIGN and BARD networks in central California. While none of these stations is yet operational, we have recently made progress in identifying and permitting sites as well as ordering and fabricating the instrumentation (Chapter 7). We are also actively preparing for the deployment of a permanent seismic observatory on the ocean floor in Monterey Bay, in collaboration with MBARI (Monterey Bay Aquarium Research Institute), and with support from NSF. Telemetry of data to shore will be developed either over a cable or using an MBARI mooring. This is a follow-up of the 1997 MOISE experiment and we hope it will be the first station of a larger network of ocean bottom broadband observatories off-shore California, to complement the land-based network across the North-America/Pacific plate boundary. The installation of this ocean floor station is planned at the end of summer 2001.
In the past year, we have continued to consolidate and expand our regional instrumentation, adding two stations to the BDSN (Chapter 2), one station to the NHFN (Chapter 3), and one station to BARD (Chapter 6). The BDSN station MOD fills an important gap in the distribution of stations in the northeastern corner of California, so important that it registers local seismicity that is not to be found in any of the existing earthquake catalogs (Section 12.12). In Parkfield, the situation with the location of geophysical equipment at the Haliburton House has been resolved. BDSN equipment at this site will be relocated to the USGS facilities at Carr Hill and HRSN equipment (Chapter 4) will be relocated to a California Division of Forestry facility.
The "MultiSHEAR" software is now fully implemented at all our Quanterra dataloggers and will soon allow us to telemeter data from multiple borehole HFN and bridge sites and extend the capabilities of central site triggering (e.g. Chapter 8). Efforts to improve the quality of our data and the procedures for real time earthquake characterization are described in Chapters 8 and 9 and in Sections 12.5, 12.7, and 12.16.
On the NCEDC front, we have finished the migration from the old to the new 2.5 Terrabyte masstore, and transfer of data from Menlo Park is now performed electronically and automatically, greatly facilitating the archival process (Chapter 10). The NetDC software, which links regional and global seismic datacenters seamlessly, and to the development of which we have actively contributed is now operational and we have helped migrate it to the SCECDC so that all digital data from California can now be accessed by users using a unified procedure.
BSL contributions to general education have been numerous in the last year (Chapter 11), in particular through our continued participation in the Interactive University Project. Scientists at the BSL are also frequently solicited by the media and public for information about current regional and worldwide earthquakes. We respond through individual interviews and have put much effort in the last year in further developing our web interface.
Chapter III describes the main research contributions of the last year. Among others, the microseismicity dataset accumulated at borehole stations of the Hayward Fault Network, combined with InSAR data, is yielding new insights on the long term behavior of the northern Hayward Fault (Section 12.1). The occurrence of the Mw7.1 Hector Mine Earthquake (10/16/99) allowed Doug Dreger and Asya Kaverina to demonstrate the effectiveness of their quasi-automated finite fault modelling procedure using a sparse network of broadband data (Section 12.5). More generally, BSL faculty, staff and students contributed to the characterization of the rupture process of the 3 large earthquakes of the fall 1999 (Turkey, Taiwan and Hector Mine, Sections 12.3, 12.4, 12.5, and 12.6). We have also made progress in characterizing three-dimensional crustal structure in northern California and its effects on regional wave propagation (Sections 12.8, 12.9, and 12.10) and in utilizing GPS and InSar data to better characterize regional tectonics (Sections 12.14, 12.15, and 12.17).
In addition to research on regional earthquake and tectonics, the BSL is actively involved in global structure research, using tomographic (e.g. Sections 12.17, 12.19, and 12.20) or forward modelling techniques (Sections 12.21 and 12.22). We also have continued work on characterizing inner core anisotropy/structure, illustrating once more the existence of strong small scale lateral variations affecting core sensitive phases (Section 12.18).
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, which owes its existence to the efforts of Christina Jordan and Eleanor Ka. I also wish to thank the individuals who attend the weekly staff meetings and contribute to the smooth operation of the BSL facilities: Ray Baxter, Ludovic Bréger, Rich Clymer, Doug Dreger, John Friday, Steve Fulton, Lind Gee, Wade Johnson, Bill Karavas, Tom McEvilly, Rick McKenzie, Mark Murray, Bob Nadeau, Doug Neuhauser, Charley Paffenbarger, David Rapkin, Fumiko Tajima, Bob Uhrhammer, and Stephane Zuzlewski. Eleanor Ka, Christina Jordan, and Bari Burton provide invaluable support, under often stressful conditions, to the administration of our lab, and clearly, no work would ever get done without Charley Paffenbarger's quiet and efficient management of our computer systems. I also wish to thank our undergraduate assistants/interns Lisa Krain, Sheer El Showk, Jacob Fink, Christine Ng, Valier Pacheu, Amanda Chung, and visiting from France Nicolas Houy 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.
Last but not least, I wish good luck with their careers to Chaincy Kuo and Christiane Stidham, who have completed their PhD's in 1999-2000, and now hold post-doctoral positions at LBNL and Harvard, respectively, as well as to Ray Baxter, who left the BSL staff to join the "dot.com" world at Inktomi.
Sept 23, 2000