Facilities - Seismic Observatories

Data Centers

NEES Data Center

The NEES@UCSB data center receives data streams from several remote field sites.  These sites, equipped with seismic sensors for monitoring ground shaking, pressure sensors for monitoring liquefaction, and video telepresence cameras, deliver their data to the local ERI network servers. The ERI data center servers provide researchers access to the earthquake data via a web-based search and download portal (nees.ucsb.edu). The real-time streaming data is also forwarded to other regional seismic monitoring networks and national data centers.

Instrumentation and Seismic Observatories Programs at ERI

ERI is home to significant instrumentation and research efforts focused on understanding the physics of the earthquake process and the effects of earthquakes on the built environment. These require not only computational facilities for completing theoretical modeling of wave propagation and earthquake source process simulation, but also field observatories for monitoring earthquake activity. These field observatories provide the control data for testing our theoretical models and simulation techniques in order to allow us to determine if our models are matching real observations of earthquakes.

ERI operates a number of field facilities for monitoring earthquakes. The cost of installing and operating both portable instrumentation and permanent field sites can be quite high, so these costs are shared by many funding agencies. These combined resources as well as some local institutional resources and in-kind support from other agencies are used to maintain the overall instrumentation and seismic observatories program at ERI.

Portable Broadband Instrument Center

The Portable Broadband Instrument Center (PBIC) was established in 1991 by the Southern California Earthquake Center (SCEC) to provide researchers with year-round access to a "pool" of high-resolution, digital seismic recording equipment. The PBIC is managed by Principal Investigator Jamie Steidl.

Sensors consist of high output short period velocity transducers to record very small ground motion, force balance accelerometers designed to stay on-scale (up to +-2G) for the strong ground motion expected from very large earthquakes, and intermediate period weak motion sensors that provide increased frequency bandwidth to allow better investigation of deep basins and teleseismic or global earthquake monitoring. A broad dynamic range of recording is obtained by pairing both weak motion and strong motion sensors with a single DAS.  The combination of dataloggers and sensors allows recording from as low as M1 earthquakes all the way to M8+ earthquakes on scale. In addition, these stations have the capability to stream the data continuously back to UCSB and the regional monitoring networks in real-time.

NEES@UCSB

The NEES @UCSB program, "Permanently Instrumented Field Sites for Soil-Foundation-Structure Interaction (SFSI)", one of 14 experimental earthquake engineering facilities in the U.S., is a 10-year operation to monitor earthquake activity at two field sites in Southern California as well as to facilitate active experimentation at these sites over the decade long program.  The overarching goal of the NEES@UCSB field site program is to improve on our ability to generate analytical and empirical models for accurate simulation of how the ground responds and deforms when shaken by earthquakes and to understand how this seismically induced shaking affects building structures and foundations.

The Garner Valley NEES site

The NEES Garner Valley Downhole Array (GVDA), established in 1989, is primarily a ground motion research site located in a seismically active region of California, 7 km from the San Jacinto fault and 35 km from the San Andreas fault. The Garner Valley site is very well suited to the study of soil-foundation-structure interaction and liquefaction. The area is located near several active faults on low density alluvial soil with a near surface water table. Pressure transducers within the liquefiable sediments, and accelerometers at the surface and at various depths within the soil column and in the bedrock below. .

The NEES Wildlife Liquefaction Array field site

The Wildlife Liquefaction Array (WLA) is a ground motion monitoring and liquefaction research site. Located at the southern most terminus of the San Andreas Fault system, the WLA field site records numerous earthquakes daily in this seismically active area. WLA is situated in California's Imperial Valley on the west bank of the Alamo River 13 km due north of Brawley, California and 160 km due east of San Diego. Records from WLA provide essential information to scientists who study ground response, ground failure, and liquefaction as this site is highly susceptible to increases in pore pressure. Instrumentation of the site began in 1982by the US geological Survey, and was upgraded in 2004 through the NEES program.

UCSB-Operated Observatories - Borrego Valley Downhole Array & Hollister Earthquake Observatory

Both sites were donated by Kajima Engineering and Construction Corp. and Agbabian Associates. In 1993, the Borrego Valley downhole array (BVDA) was established near Borrego Springs, in Southern California. In this array there are four borehole instruments extending depths of 9, 19, 139 and 238 m. In addition, BVDA has 15 surface instruments extending in two directions across the Borrego Valley, and a remote rock site at the edge of the valley that includes surface and borehole sensors. The BVDA site is complementary to the NEES facilities in that it represents a different soil condition (dry vs. wet) and slightly stiffer material properties.

The Hollister Earthquake Observatory (HEO) was established in 1991 and is located in the Salinas Valley about 10 kilometers from the San Andreas Fault. The ground motion array consists of a vertical array of six accelerometers in Quaternary alluvium, and three accelerometers installed at a remote rock station, 3 km to the Northeast. At the HEO main soil station accelerometers are located at 192, 110, 50, 20, 10, and 0 meters depth, going from crystalline rock at the bottom, up through consolidated and unconsolidated alluvium to the surface. Three sensor locations, surface Sandstone, surface Granite, and GL-53 meter borehole Granite are instrumented at the remote rock station.

The SCEC Borehole Instrumentation Program

The Southern California Earthquake Center (funded by USGS and NSF), has supported the instrumentation and maintenance of borehole and surface instruments at locations throughout southern California for the past two decades. These stations are collaborative with the regional networks, and typically include a surface and single borehole sensor, with the data streaming directly to the regional networks, and archived at the Southern California Earthquake Data Center (www.data.scec.org).