A highlight of the past year has been the successful completion of the NSF funded project in collaboration with Tom VanZandt of Metrozet for the design and testing of new electronics for the STS-1 very broadband seismometer. This exceptional seismometer, installed at several hundred seismic stations around the world, and in particular at 10 of the BDSN sites, was developed in the 1970's but is no longer produced, raising concerns about its longevity and the need for a high quality replacement. The BSL developed a test-best and participated in the testing of successive iterations of electronics developed by Metrozet. The new electronics present several attractive features, in particular capabilities for remote calibration. After testing at UC Berkeley's Byerly vault, they were installed for further testing at Hopland (HOPS). They are now ready for production.
The prototype earthquake early warning system developed by Prof. Richard Allen has been implemented in our real time system and is being tested and improved in this framework. It is already providing useful by-products, such as the ability to obtain reliable shake maps in just over a minute, compared to 4+ minutes in the operational system used by CISN.
As in previous years, BSL's infrastructure development efforts have centered around several major projects:
The main goal of the CISN (see Section 3.2.) 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 cultures. Much effort has gone over the past few years to develop coordinated software between southern and northern California and in northern California, between Berkeley and USGS/Menlo Park. These two institutions are joined together in the Northern California Earthquake Management Center(NCEMC). A highlight of the past year has been the long awaited retirement of the CUSP real-time earthquake timing system in Menlo Park. BSL staff continue to spend considerable efforts in organizational activities for CISN, notably by participating in the CISN Project Management Group (Neuhauser and Hellweg), which includes weekly 2 hour phone conferences, and the Standards Committee (Neuhauser-chair, Hellweg, Lombard), which strives to define and coordinate software development tasks. Romanowicz and Hellweg serve on the CISN Steering Committee. Doug Neuhauser has also been serving on the CISN Steering Committee in the transition period following Lind Gee's departure in summer 2005. 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.
The BSL concluded an agreement in June 2004 with IRIS to contribute 19 stations of the BDSN to USArray, while the experiment is deployed in California. This includes 17 existing stations and the two recently installed sites: GASB and MCCM. In the past year, BSL has continued to acquire telemetered data from these and other northern California USArray stations and to pay particular attention to the maintenance of those permanent sites which are part of USArray. As USArray moves out of California starting in Fall 2007, BSL has been preparing to take over 7 of the USArray sites. This involves transfer of site permits, preparation of BSL equipment (seismometers and dataloggers funded through FEMA and OSN grants) and securing new telemetry paths where needed.
The Parkfield borehole network (HRSN, see Section 3.4.) continues to play a key role in support of the Earthscope SAFOD (San Andreas Fault Observatory at Depth) drilling project, by providing low noise waveforms for events in the vicinity of the target drilling zone. In the past year, integration of the HRSN data streams into the NCSN triggering scheme has been completed, in support of researchers working on repeating micro-earthquakes. Also, the upgrade of the telemetry system has been completed. HRSN data are now telemetered over the USGS T1 line to Menlo Park and then on to Berkeley over the joint T1 line between the two institutions.
In the past year, the Northern Hayward Fault Network (NHFN, see Section 3.3.) has continued to expand. St. Mary's College station (SM2B) has been completed and four additional sites have been drilled, have downhole packages, and are awaiting connection to dataloggers. This will bring the total number of borehole NHFN sites to 18. On-going network maintenance involves regular inspection of the collected seismic waveform data and spectra for nearby seismic events, and for noise samples, in order to assure that the instruments operate at maximum performance to capture the source spectrum of micro-earthquakes down to negative magnitudes.
The BARD continuous GPS (C-GPS) network (see Section 3.5.) has focused its efforts to convert three additional sites to acquire data at 1Hz sampling rate (up from the standard 15-30 sec rate), bringing to 15 the total number of stations upgraded, with the goal of using these data in complement to seismic data for real-time earthquake notification. We have been working with our colleagues at the US Geological Survey in Menlo Park to establish a joint GPS real time data acquisition system and integrate it with our existing seismic earthquake notification system. We have been working with EB Parks, EBMUD and the Plate Boundary Observatory (PBO) of Earthscope, to acquire data from their GPS stations in real time. In exchange for real time data feeds from East Bay agencies, we can provide RTK (Real-Time Kinematic) data for land surveys that they perform.
The NCEDC (see Section 3.6.) continues archival and on-line distribution of data from expanding BDSN, NHFN, HRSN, BARD, Mini-PBO, and other networks and data collections in northern California and Nevada, including telemetered continuous data from USArray stations in northern California and vicinity. We are continuing to receive data from the SAFOD pilot hole and main hole and data from 15 SCSN (southern California) broadband sites as part of the CISN robust ``backbone". In late 2006, we begun to archive and distribute a single unified northern California earthquake catalog, obtained in real-time from the NCEMC through database replication from the NCEMC's real-time systems. In the past year, the NCEDC has supported the NCEMC earthquake analysis by providing real-time access to earthquake parameters and waveforms for the CISN Jiggle earthquake review software, and has implemented software and procedures to read and archive continuous NCSN seismograms from tapes for the period 2001-2005, beginning the processing of these tapes.
Berkeley Seismological Laboratory
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