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Director's report


Background

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 our ORU apart, 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 about 20 digital broadband and strong motion seismic stations, the Berkeley Digital Seismic Network (BDSN), with continuous frame-relay phone 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 Transportation department, 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 18 out of its 40-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.

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, as well as our Earthquake Research Affiliates Program.

Recent Highlights

First and foremost, I would like to stress the difficult conditions under which our staff has worked in the past year, due to the on-going renovation of McCone Hall, including a major move, in January 1999, of our offices and operations from the 4th and 5th floor on the one hand, and temporary quarters in Wellman Trailers on the other, requiring much time and effort to ensure the proper and continuous functioning of our computer systems, data center hardware and telemetry. The smooth operation of the BSL has continued to be disrupted, after the move, and up to this date, by miscellaneous problems related, in particular to the ventilation and electrical systems in the building. In spite of that, much has been accomplished in the past year. I would like to give special thanks to Doug Neuhauser, Charley Paffenbarger and Lind Gee for devoting much of their time to help us live smoothly through this troubled period, of which the end is hopefully in sight.

In 1998-1999, we have continued to consolidate and expand our regional instrumentation programs, adding two SF Bay Area stations to the BDSN, 3 new BARD stations, and upgrading telemetry capabilities at various sites. Notably, with the help of funding from OES, we have put in place a redundant data acquisition and processing system at the OES headquarters in Sacramento. This system is designed to provide bare-bones back-up capabilities for our REDI program (in addition to the two twin data processing computers, Athos and Porthos, at the BSL) in the event that communications are lost to our central processing site during a major earthquake. The Sacramento computer receives data from 6 of our BDSN stations over frame-relay and has worked well on the occasion of several recent M4-5 events. As described further in this report, we are in the process of developing enhanced processing methodologies that utilize the broadband waveform information from a small number of stations in order to provide reliable estimates of source location and size using this back-up facility.

In the past year, with the help of funding from the USGS, we have been upgrading the NCEDC mass-store from an initial capacity of 600 Gbytes (optical discs, capacity reached at the end of 1998) to 2.5 Terrabytes (magneto optical discs). This process has been much slower than anticipated, due to unexpected hardware and software problems with the new mass-storage system, but should provide us room for the ever increasing quantity of data collected over our networks, for the immediate future. Notably, the NCEDC has played an active role in the development of a program lead by IRIS to link different seismological Data Centers worldwide over the internet (NetDC) in order to rationalize researchers' access to complementary datasets. The prototype software is in place and operational and the capability will be released publicly during the Fall'99 AGU meeting in San Francisco.

So far, progress in densifying instrumentation in the San Francisco Bay Area and northern California with state of the art systems to provide timely information on ground shaking and earthquake processes has been progressing steadily, but slowly, due to limited funding. Compared to southern California, where over 150 broadband/strong motion seismic stations are being installed in the framework of the TriNet program, and an equivalent number of permanent GPS stations in the framework of the SCIGN program, our capabilities are still modest. However, much progress has been achieved in the past year in northern California in designing the plans for a northern California component of the TriNet program. The three institutions involved, UC Berkeley, CDMG and USGS/MP have drafted a proposal, with input from the OES, for the enhancement of infrastructure in northern California, with particular emphasis on developing capabilities for rapid estimation of strong ground shaking (i.e. ShakeMaps) (See MOA attached as Appendix). While no specific funding for this ~$20 M initiative has yet been secured, the BSL staff and faculty have been actively involved in all aspects of the design of this plan.

In January 1998, we submitted a collaborative proposal to the MRI program of NSF, to enhance the infrastructure for the monitoring of tectonic deformation in central California. Funding from the resulting grant and matching funds from the participating institutions (UC Berkeley, Carnegie Inst. of Washington, UC San Diego, USGS/MP) will serve to install on the order of 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. This will serve as a pilot project for a much broader initiative, the "Plate Boundary Observatory", currently being prepared in the framework of an MRE/NSF program ("Earthscope") by the US geophysical community.

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 and SAFOD programs, which are part of Earthscope.

Finally, in collaboration with MBARI (Monterey Bay Aquarium Research Institute), we are beginning to plan the installation of a permanent seismic observatory on the ocean floor in Monterey Bay. 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 network of ocean bottom broadband observatories off-shore California, to complement the land-based network across the North-America/Pacific plate boundary.

Sections 9 and 10 of this report describe the research accomplishments at the BSL during the past year. You will note that our research encompasses many regional, earthquake and tectonics related problems on the one hand, and fundamental problems in global geophysics, through our work in global tomography and more generally, through modelling of teleseismic travel times and waveforms. A recent focus has been the re-evaluation of simple models of inner core anisotropy, in the light of recent results on the strong heterogeneity at the base of the mantle.

Finally, the BSL contributions to general education have been enhanced in the last year, as described in the Outreach section, and 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.

I wish to thank our technical and administrative staff, scientists and students for their contributions to this annual report and wish good luck with their careers for the 3 graduate students have completed their PhD's in 1999: Ludovic Bréger, Charles Mégnin, and Paul Parker. I also wish to thank our undergraduate assistants/interns Derek Lerch, Sheer El Showk, Jacob Fink, Sean Ford, Christine Ng, Shawn Lawrence, Valier Pacheu, Enrou Yang, and visiting from France Sébastien Rousset for their contributions to our research.



Barbara Romanowicz

Sept 23, 1999


 
Table 1.1: Table of standard acronyms and abbreviations used in this report.
AGU American Geophysical Union
ANSS Advanced National Seismic System
BARD Bay Area Regional Deformation
BDSN Berkeley Digital Seismic Network
BSL Berkeley Seismological Laboratory
CalREN California Research and Educational Network
CDMG California Division of Mines and Geology
CLC Campus Laboratory Collaboration
EM Electromagnetic
EPRI Electric Power Research Institute
FBA Force Balance Accelerometer
FRAD Frame Relay Access Device
GPS Global Positioning System
HFN Hayward Fault Network
HRSN High Resolution Seismic Network (Parkfield)
IGS International Geodetic Service
InSAR Interferometric Synthetic Aperture Radar
IRIS Incorporated Research Institutions for Seismology
ISC International Seismological Center
ISTAT Integrating Science, Teaching, and Technology
IUP Interactive University Project
JPL Jet Propulsion Laboratory
LBNL Lawrence Berkeley National Laboratory
LLNL Lawrence Livermore National Laboratory
MRI Major Research Initiative
MRE Major Research Equipment
MT Magnetotelluric
NCSN Northern California Seismic Network
NCEDC Northern California Earthquake Data Center
NEHRP National Earthquake Hazards Reduction Program
NGS National Geodetic Survey
NSF National Science Foundation
OES Office of Emergency Services
PVC Permanent Virtual Circuits
REDI Rapid Earthquake Data Integration
SAPSE South Island Passive Seismic Experiment
SAR Synthetic Aperture Radar
SEED Standard for the Exchange of Earthquake Data
SIO Scripps Institutions of Oceanography
SSA Seismological Society of America
UCB University of California at Berkeley
ULF Ultra Low Frequency
UNAVCO University NAVSTAR Consortium
USGS United States Geological Survey


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