California Integrated Seismic Network

Introduction

Advances in technology have made it possible to integrate separate earthquake monitoring networks into a single seismic system as well as to unify earthquake monitoring instrumentation. In California, this effort began in the south with the TriNet Project. There Caltech, the California Geological Survey (CGS), and the USGS combined efforts to create a unified seismic system for southern California. With major funding provided by the Federal Emergency Management Agency (FEMA), the California Governor's Office of Emergency Services (OES), and the USGS, the TriNet project provided the opportunity to upgrade and expand the monitoring infrastructure, combining resources in a federal, state and university partnership. In 2000, the integration effort expanded to the entire State with the formation of the California Integrated Seismic Network (CISN, see 2000-2001 Annual Report). To this end, UC Berkeley and the USGS Menlo Park and Pasadena offices joined forces with Caltech and the CGS. The CISN is now in the eighth year of collaboration and its seventh year of funding from the OES.

CISN Background

Organization

The organizational goals, products, management, and responsibilities of the CISN member organizations are described in the founding MOU and in the strategic and implementation plans. To facilitate activities among institutions, the CISN has formed three management centers:

• Southern California Earthquake Management
  Center: Caltech/USGS Pasadena
• Northern California Earthquake Management
  Center: UC Berkeley/USGS Menlo Park
• Engineering Strong Motion Data Center:
  California Geological Survey/USGS National Strong Motion Program

The Northern and Southern California Earthquake Management Centers are operating as twin statewide earthquake processing centers serving information on current earthquake activities, while the Engineering Strong Motion Data Center has the responsibility for producing engineering data products and distributing them to the engineering community. The Steering Committee, made up of two representatives from each core institution and a representative from OES, oversees CISN projects. The position of chair rotates among the institutions; Rob Clayton took over as chair of the Steering Committee in June 2008 from Jeroen Tromp to complete Caltech's tenure. An external Advisory Committee represents the interests of structural engineers, seismologists, emergency managers, industry, government, and utilities, and provides review and oversight. The Advisory Committee is chaired by Stu Nishenko of Pacific Gas and Electric Company. It last met in October 2007. Agendas from the meetings and the resulting reports may be accessed through the CISN Web site (http://www.cisn.org/advisory). The Steering Committee has formed other committees, including a Program Management Group to address planning and coordination and a Standards Committee to resolve technical design and implementation issues. In addition to the core members, other organizations contribute data that enhances the capabilities of the CISN. Contributing members include: University of California, Santa Barbara; University of California, San Diego; University of Nevada, Reno; University of Washington; California Department of Water Resources; Lawrence Livermore National Lab; and Pacific Gas and Electric.

CISN and ANSS

The USGS Advanced National Seismic System (ANSS) is being developed along a regionalized model. Eight regions have been organized, with the CISN representing California. David Oppenheimer of the USGS represents the CISN on the ANSS National Implementation Committee (NIC). Over the past 9 years, ANSS funding in California has been directed primarily to the USGS Menlo Park to expand the strong-motion instrumentation in the San Francisco Bay Area. As a result, more than 100 sites have been installed or upgraded, significantly improving the data available for ShakeMaps. As the ANSS moves forward, committees and working groups are being established to address issues of interest. BSL faculty and staff have been involved in several working groups of the Technical Integration Committee, including Doug Dreger, Pete Lombard, Doug Neuhauser, Bob Uhrhammer, and Stephane Zuzlewski.

CISN and OES

The California Governor's Office of Emergency Services has had a long-term interest in coordinated earthquake monitoring. The historical separation between Northern and Southern California and between strong-motion and weak-motion networks resulted in a complicated situation for earthquake response. Thus, OES has been an advocate of increased coordination and collaboration in California earthquake monitoring and encouraged the development of the CISN. In FY01-02, Governor Gray Davis requested support for the CISN, to be administered through OES. Funding for California Geological Survey, Caltech and UC Berkeley was made available in spring 2002, officially launching the statewide coordination efforts. Following the first year of funding, OES support led to the establishment of 3-year contracts to the UC Berkeley, Caltech, and the California Geological Survey for CISN activities. The first multi-year award covered activities in 2002-2005. The three-year contract for 2006-2008 has just been completed. Past CISN-related activities are described in previous annual reports.

2007-2008 Activities

The CISN funding from OES has supported a number of activities at the BSL during the past year.

Adopting USArray Stations

In late 2003, the CISN concluded a memorandum of agreement with the Incorporated Research Institutions in Seismology (IRIS) covering the duration of the USArray project in California. As a result, data from 19 stations operated by the BSL and 41 stations operated by Caltech were contributed to USArray's travelling array (TA) during its California deployment. The BSL also provided accelerometers for use at TA sites which might be of interest as future BDSN stations. We monitored the data from these stations in real time and included the data in ShakeMaps and moment tensors. In addition, data from these TA stations were included in our development of new parameters that are valid statewide for determining $M_{L}$ (see Research Study 34.). The TA moved out of California during the fall of 2007, and the BSL adopted eight of the sites. Instrumentation has been installed at RAMR, HAST, HATC, HELL, and SUTB (see Section 1). Support for the equipment has come from FEMA Hazard Grant Mitigation Program Funds and from CISN funding. Vaults have been left open at P01C, S04C, and V03C, which the BSL will instrument when funding becomes available.

Figure 3.6: Map showing the geographical distribution of the CISN partners and centers. The communications ``ring" is shown schematically with installed links (solid lines).

Figure 3.7: Map showing the 30 stations selected to send data directly to the Northern and Southern California processing centers, and the 5 stations that send data directly to the Engineering Data Center and the Southern California processing center.

Northern California Earthquake Management Center

As part of their effort within the CISN, the BSL and the USGS Menlo Park are implementing the new generation of the Northern California joint notification system. Section 8 describes the operations of the existing Management Center and reports on the design and implementation progress. In order to move ahead with plans for restructuring the Northern California earthquake monitoring system, the USGS Menlo Park and BSL have been improving their communications infrastructure. At present, the BSL and the USGS Menlo Park are connected by two dedicated T1 circuits. One circuit is a component of the CISN ring, while the second circuit was installed in 2004-2005 (Figure 3.8) to support dedicated traffic between Berkeley and Menlo Park above and beyond that associated with the CISN. The installation of the second dedicated T1 between Berkeley and Menlo Park freed up a frame-relay connection deployed by the BSL as part of the CalREN project in mid-1990s. The BSL has reconfigured this frame-relay circuit to serve as a second data acquisition link. BDSN data acquisition is now distributed between two frame-relay T1 circuits, eliminating what had been a single point of failure. An additional Permanent Virtual Circuit (PVC) has also been implemented at each BDSN site so that each station has connections to both T1s. This has improved the robustness of data acquisition at the BSL by providing redundancy in the incoming circuit. In the long term, the BSL and USGS Menlo Park hope to be connected by high-bandwidth microwave or satellite service. Unfortunately, we have not yet been able to obtain funding for such an additional communication link.

Figure 3.8: Schematic diagram illustrating the connectivity between the real-time processing systems at the USGS Menlo Park and UC Berkeley, forming the Northern California Management Center, and with other elements of the CISN.

Statewide Integration

BSL staff are involved in many elements of the statewide integration effort. The Standards Committee, chaired by Doug Neuhauser, continues to define and prioritize projects important to the development and implementation of the statewide earthquake processing system and to establish working groups to address them (see minutes from meetings and conference calls at http://www.cisn.org/standards/meetings.html). Dual Station Feeds: Early in the existence of CISN, ``dual station feeds" were established for 30 stations (15 in Northern California and 15 in Southern California) (Figure 3.7). The Northern California Earthquake Management Center (NCEMC) is using data from the Southern California stations to estimate magnitudes on a routine basis. A subset of these stations are being used for the moment tensor inversions, a computation that is sensitive to the background noise level. Data Exchange: Pick exchange was initiated between the NCEMC and its Southern California counterpart in 2001-2002. The software CISN has developed to produce and exchange the reduced amplitude timeseries has also been completed. Currently, these timeseries are being exchanged at the NCEMC, but not yet statewide. Using a common format, the CISN partners continue to exchange observations of peak ground motion with one another following an event or a trigger. This step increases the robustness of generating products such as ShakeMap, since all CISN partners now exchange data directly with one another. This also improves the quality of ShakeMaps for events on the boundary between Northern and Southern California, such as the San Simeon earthquake, by allowing all data to be combined in a single map. Finally, this is a necessary step toward the goal of generating statewide ShakeMaps. The Software Calibration & Standardization: CISN partners are working to standardize the software used for automatic earthquake processing and earthquake review, as well as to calibrate it. Currently, the software implemented at the NCEMC and at the Southern California Earthquake Management Center is very different. During the past year in the NCEMC, we have worked on preparing a version of the Southern California TriNet software for implementation as CISN software in the NCEMC.

• Magnitude: Calibrating magnitude estimates has proven to be more difficult than originally anticipated. As described in 2003-2004, evidence indicates that there is a bias between the Northern and Southern California estimates of local magnitude $M_{L}$. Efforts to understand this issue have been hampered by the lack of a good statewide dataset. Bob Uhrhammer has selected data from 180 earthquakes distributed throughout the state and comprising recordings from 976 horizontal components from the AZ, BK, CI and NC networks (see Research Study 34.). In January 2007, we agreed on a $logA_{o}$ function suitable for statewide use. Station-specific corrections for $M_{L}$ have now been defined for most broadband/strong motion stations. We are working to develop station-specific corrections for strong motion only stations, and to tie the new system in with historical stations. A final component of the magnitude efforts is the determination of a magnitude reporting hierarchy. For the near future, each region will continue to use its own preferences for magnitude reporting.


• ShakeMap: At present, ShakeMaps are generated on 5 systems within the CISN. Two systems in Pasadena generate ``SoCal" Shakemaps; 2 systems in the Bay area generate ``NoCal" Shakemaps; and 1 system in Sacramento generates ShakeMaps for all of California. The Sacramento system uses QDDS to provide the authoritative event information for Northern and Southern California. The dearth of stations in the near source region of the 2003 San Simeon earthquake raised the issues of how to measure the quality of a ShakeMap and how to quantify the uncertainty. A subset of the Working Group worked on this issue, based on the work of Hok and Wald (2003). Lin et al (2006) presented progress toward quantifying ShakeMap uncertainty, and ShakeMaps are now published with a grade. A second goal of this effort was to improve the robustness of ShakeMap generation and delivery by taking advantage of the fact that ShakeMaps are generated in the Bay Area, Pasadena, and Sacramento. Ongoing efforts in this direction will likely be based on the new USGS ShakeMap webpages at the National Earthquake Information Center.


• Location Codes: The CISN adopted a standard for the use of ``location" codes (part of the Standard for the Exchange of Earthquake Data (SEED) nomenclature to describe a timeseries based on network-station-channel-location) in the late fall of 2003. USGS and UC Berkeley developers modified the Earthworm software to support their use. After the transition at USGS Menlo Park away from the CUSP analysis system to Jiggle in late November, 2006, all networks in the CISN implemented location codes in their systems.


• Metadata Exchange: Correct metadata are vital to CISN activities, as they are necessary to ensure valid interpretation of data. CISN is working on issues related to their reliable and timely exchange. The CISN Metadata Working Group compiled a list of metadata necessary for data processing and developed a model for their exchange. In this model, each CISN member is responsible for the metadata for its stations and for other stations that enter into CISN processing through it. For example, Menlo Park is responsible for the NSMP, Tremor, and PG&E stations, while Caltech is responsible for the Anza data. At the present time, dataless SEED volumes are used to exchange metadata between the NCEMC and the SCEMC. The Metadata Working Group is developing a Station XML format for metadata exchange. This vehicle is expandable, and will probably allow exchange of a more comprehensive set of metadata than dataless SEED volumes, some of which may be necessary for other systems, for example in V0 formatted data.


• Leap second compatibility: Northern and Southern California databases handled leap seconds differently. A major software programming effort in the past year has been directed toward taking this into account. The data processing and analysis software now treats leap seconds consistently. All packages can be configured to pass the time information to the database in nominal or true time, as necessary.


• Standardization: The CISN's focus on standardization of software continues. For example, the BSL and the USGS Menlo Park are adapting the software running at the SCEMC for use at the NCEMC and are currently testing its various elements. The adoption of Jiggle in northern California in late November 2007 was the first step in the implementation of the new software. Current efforts are directed toward the implementation and testing of the complete system (see Section 8). This software will be offered to other regional neworks of the ANSS in the near future.

CISN Display

CISN Display is an integrated Web-enabled earthquake notification system designed to provide earthquake information for emergency response at 24/7 operations centers. First responders, organizations with critical lifelines and infrastructure, and emergency responders are invited to register for an account at http://www.cisn.org/software/cisndisplay.htm. The application provides users with maps of real-time seismicity and automatically provides access to Web-related earthquake products such as ShakeMaps. CISN Display also offers an open source GIS mapping tool that allows users to plot freely available layers of public highways, roads and bridges, as well as private layers of organizational-specific infrastructure and facilities information. The current version of CISN Display is 1.4. Its primary enhancement over the previous version is the development of a kiosk-mode for public display purposes.

Earthquake Information Distribution

The USGS hosted a workshop in October 2004 to develop plans for the installation and use of the EIDS software. Doug Neuhauser and Pete Lombard participated in this workshop, which resulted in a document outlining the steps necessary for the installation and migration of the earthquake notification system from the current Quake Data Distribution Services (QDDS) to EIDS.

Outreach

Since FY05-06, the CISN Web site (www.cisn.org) has been supported by two servers located at Berkeley and Caltech. The Web servers are set up so that the load can be distributed between them, providing improved access during times of high demand. With the increased robustness provided by the new servers, the CISN provides access to certain earthquake products directly from www.cisn.org. For example, ShakeMaps are now served directly from the CISN Web site, in addition to being available from several USGS Web servers and the CGS. The design and content of http://www.cisn.org continues to evolve. The Web site is an important tool for CISN outreach as well as for communication and documentation among the CISN partners. The CISN continues to support the dedicated Web site for emergency managers. Following a suggestion from the Advisory Committee, we have designed a Web site to provide personalized access to earthquake information. Known as ``myCISN," the Web site is available at eoc.cisn.org. Access to the Web site is limited to registered users in order to provide highly reliable access. At present, ``myCISN" is a single Web server located at UC Berkeley. However, modifications to the database are underway to allow for multiple servers in the future. A second computer, already purchased, will either be installed in Sacramento or in Southern California. As part of the CISN, the BSL is contributing to efforts to raise awareness of earthquakes and preparedness as the 140 anniversary of the 1868 Hayward Fault earthquake approaches on October 21, 2008. In particular, we will be co-hosting the Third Conference on Earthquake Hazards in the Eastern Bay Area as well as organizing and participating in other related activities.

Acknowledgements

CISN activities at the BSL are supported by funding from the Governor's Office of Emergency Services. Barbara Romanowicz and Peggy Hellweg are members of the CISN Steering Committee. Peggy Hellweg is a member of the CISN Program Management Group, and she leads the CISN project at the BSL with support from Doug Neuhauser. Doug Neuhauser is chair of the CISN Standards Committee, which includes Peggy Hellweg, Pete Lombard, and Stephane Zuzulevski as members. Because of the breadth of the CISN project, many BSL staff members have been involved, including: John Friday, Jarrett Gardner, Peggy Hellweg, Bill Karavas, Alexei Kireev, Rick Lellinger Pete Lombard, Doug Neuhauser, Charley Paffenbarger, Bob Uhrhammer and Stephane Zuzlewski. Peggy Hellweg contributed to this section. Additional information about the CISN is available through reports from the Program Management Group.

References

Hok, S., and D. J. Wald, Spatial Variability of Peak Strong Ground Motions: Implications for ShakeMap Interpolations, EOS. Trans. AGU, 84(46), F1121, 2003.

Lin, K-W., D. Wald, B. Worden and A.F. Shakal, Progress toward quantifying CISN ShakeMap uncertainty, Eighth National Conference on Earthquake Engineering, San Francisco, California, April 18-21, 2006.