History of TriNet
Southern California is unique because it is one of the few places on earth
where a plate boundary extends across the continental crust rather than on
the ocean floor. Because earthquakes are concentrated along plate boundaries,
California has alot of earthquakes. California also has a
large population, and the areas of highest population density are all near
the San Andreas fault, the major boundary between the North American and
Pacific Plates, which extends along the length of California.
Each day there are about 30 earthquakes recorded in southern California,
although most are too small to be felt. A typical year produces over 10,000
earthquakes. The most recent significant earthquake in southern California
was the magnitude 6.7 Northridge earthquake on January 17,
1994. Because of its location in a highly populated urban area with a high
density of seismographs, it is the most well-recorded and thoroughly-studied
earthquake ever. The last great earthquake in southern California was the
magnitude 7.9 earthquake in 1857 that ruptured the southern
section of the San Andreas Fault. Sometime in the future, there will be
another great earthquake like it in southern California.
The three partner agencies in TriNet - The California Institute of
Technology (
Caltech), the U.S. Geological Survey (USGS), and the California Geological Survey
(CGS) - have been
operating separate seismic networks for many years. Since the 1960's the
Caltech Seismological Laboratory, in collaboration with the USGS, has operated
a telemetered analog seismic array in southern California. With more than
200 remote stations, this array, the Southern California Seismic Network
(SCSN) has been the major source of earthquake
information in southern California and is used to advise more than a dozen
governmental agencies, including California Office of Emergency Services in
Sacramento, the Los Angeles County Emergency Information Bureau, the Pacific
Tsunami Warning Network, the Office of Emergency Preparedness, and electric,
gas, and transporation utilities.
The SCSN earthquake catalog is one of the most complete earthquake catalogs
in the world with over 344,000 events starting in 1932. The SCSN also
provides digital waveforem data, phase arrival data, and first motion data
at all timed stations for each recorded earthquake.
The USGS also operates the National Strong Motion Program
(NSMP) network
which consists of 571 seismic stations nationwide that record strong
ground motions.
CGS operates the California
Strong Motion Instrumentation Program (CSMIP) network consisting of well over
400 analog strong motion sensors in California. CMDG provides waveform data
sets after significant earthquakes.
In late 1987, the TERRAscope project began, and presently 19 digital
TERRAscope stations have been installed in southern California.
To facilitate real-time distribution of earthquake data, Caltech and the USGS,
in cooperation with corporate partners, started the Caltech
US Geological Survey Broadcast of Earthquakes (CUBE) project in 1990.
Also, in 1990 the Southern California Earthquake Center (SCEC) Data Center
opened at Caltech. The SCEC Data Center provides
earthquake data to researchers over the internet.
Then in 1994 the California Research and Education Network (CalREN) grant
program, funded by Pacific Bell, provided
a grant to connect remote digital
seismographic stations to a central site, Caltech in Pasadena, for real-time
monitoring of earthquake activity in southern California.
The project's objective was to demonstrate the increased speed and accuracy
of earthquake information that can be provided with a fully
digital network. TERRAscope, provided the digital signals that were being
transmitted to Pasadena using new digital data transmission technologies.
In 1994, Caltech and Kinemetrics Inc.
were funded to begin the Automated
Strong Motion Monitoring Program (AMOES) that consisted
of developing the K2 and installation of 16 K2 instruments in the greater
Los Angeles region.
TriNet was funded in 1997 to create a better, more effective real-time
earthquake information system for southern California. Caltech, USGS, and
CGS are leveraging their resources with private partners to improve the
current system, building on the strengths of TERRAscope.
TriNet will incorporate new technologies enabling a much greater bandwidth and
dynamic range to provide accurate and vital information within minutes of an
earthquake. Our goal is to mitigate the impact of future large earthquakes in
Southern California. Caltech's Seismological Laboratory and the USGS are
reconfiguring and modernizing Southern California's existing seismic network,
the Southern California Seismic Network (SCSN), with real-time transmissionand processing capability and new digital instruments at 200 sites. CGS will
upgrade and expand strong motion instrumentation at 400 sites in their
existing California Strong Motion Instrumentation Program
(CSMIP) network and the USGS National Strong Motion Program (NSMP) will
upgrade 35 of their current southern California sites to retrieve near
real-time ground motion parameters and collect data from improving building
codes.
TriNet Description
The TriNet system includes two types of sensors:
- A strong-motion accelerometer, which records strong ground motion. These
are useful both for engineering and seismological applications.
- A broad-band seismometer, best placed in quiet locations, to measure
ground motion in very small to moderate earthquakes. Seismologists can use
these data to estimate the ground motion we should expect from very large
earthquakes. The capability to simulate potential large
earthquakes is useful to many users, including engineers designing structures
such as skyscrapers, bridges, highways, or dams.
Signals from the seismic stations are transmitted to the central processing
facility at Caltech via digital phone lines (frame relay), radios, microwave
links, and the Internet. The seismic data are analyzed immediately to answer
the important questions: Where did the earthquake occur? How big was it? What
was the distribution of shaking? What fault did it occur
on? What was the type of faulting? The information will then be available
through the Internet and sent directly to cost-sharing partners through a
commercial paging system or a secure Intranet.
TriNet products include:
- Emergency Response
TriNet is able to rapidly advise the media, government agencies, disaster
response teams, and the utilities so that informed decisions may be made as
to where to dispatch personnel and equipment after a damaging earthquake.
Another TriNet goal is to provide training for emergency managers
and earthquake engineers to facilitate the efficient use of TriNet products.
All of the TriNet data are available through the Internet at this website. In
addition, Caltech/USGS Broadcast of Earthquakes (CUBE) project is distributing
TriNet information rapidly to Caltech's Earthquake Research Affiliates,
providing user support and improving real-time distribution. The
Southern California Earthquake Center (SCEC) Data Center is providing a
long-term data archive, accessible over the Internet.
- Research
The automatically broadcasted information and other data are used by
scientists to assess the status of seismic activity on a daily basis. The
high quality and high density of digital data will
enable more accurate and detailed studies of earthquake hazards,
seismotectonics, crustal velocities, source processes, and characteristics of
the interior of the earth, among many other important research topics.
- Pilot Seismic Computerized Alert Network (SCAN)
Pilot seismic computerized alert network is an emerging technology that will
provide the capability
to recognize and send notification that an earthquake is in progress before
shaking from that event arrives at a distant site. Such alerts may provide
a lead time of seconds to several tens of seconds before
the most damaging shaking arrives. Some potential uses for computerized alerts are
stopping trains, protecting fragile facilities, interrupting handling of toxic
chemicals, securing power supplies, databases, and bringing elevators to the
closest floor. We are prototyping the technology, although
the present capabilities do not include the robustness and backup systems
necessary to make this a viable system.
Below is a graphic representation of the TriNet layout. Note that there are
multiple methods for data retrieval from seismic
stations. Once the information arrives at the central processing site
many different automated operations are performed, including event
data storage, event identification and processing, and user notification.
Funding
Major funding has been provided by:
California Geological Survey
California Governor's Office of Emergency Services
California Institute of Technology
Federal Emergency Management Agency
United States Geological Survey
Additional contributions:
Caltrans
Ida H.L. Crotty
GTE
Donna & Greg Jenkins
Southern California Edison
Sun Microsystems Inc.
History, Description & Funding
