MODERN BROADBAND
EARTHQUAKE MONITORING:
SAINT LOUIS UNIVERSITY

Seismic Monitoring

Earthquake monitoring in Missouri and neighboring states is a cooperative multi-institutional effort. Participating groups include the University of Kentucky, the University of Memphis, Lamont-Doherty Earth Observatory of Columbia University, the U. S. Geological Survey, and Saint Louis University. Instrumentation operated by the University of Memphis primarily monitors earthquakes in the New Madrid Seismic Zone and is capable of locating very small events. The University of Kentucky and LDEO emphasize on-scale recording of large New Madrid events. Saint Louis University also contributes to the monitoring of New Madrid earthquakes, but their specific role is to monitor earthquakes in the broader central U. S. region. Saint Louis University and the University of Memphis are jointly responsible for the Cooperative New Madrid Seismic Network (CNMSN). In addition to having different sensitivities, the instruments deployed by various groups sample different frequencies of ground motion and may have triggered or continuous recording.

Broadband Network

Saint Louis University, in their contribution to both the CNMSN and broader regional monitoring, has focussed on broadband, high dynamic range continuous recording. The accompanying figure shows proposed and existing locations of broadband stations in the region.

Broadband stations are operating at CCM (IRIS), OXF (USNSN), WVT and WCI (Billiken/USNSN), and SLM, BLO, UTMT, MPH, PLAL, SIUC and UALR (CNMSN). The sites at FVM is ready for installation, and that at PVMO will be prepared soon.

The unique aspects of SLU broadband stations are its use of modern communication technology, satellite communication and the Internet, and cooperation with regional universities. Because the Internet provides relatively inexpensive data transfer, some of the instruments are being deployed at university facilities. Deployment in populated regions, even though higher cultural noise can be high, is especially important since we are interested in the larger earthquakes that will shake communities. The cooperating universities are the University of Indiana (BLO), Southern Illinois University at Carbondale (SIUC), the University of Memphis (MPH), the University of Tennessee at Martin (UTMT), and the University of Arkansas Little Rock (UALR).

Example of daily seismogram available on the WWW. This is the M_W = 7.1 Turkey earthquake of November 12, 1999 recorded at St. Louis.

The purposes of the broadband deployment are to:

• Record significant earthquake (M > 3) motions on scale for source and ground motion studies

• Surround significant earthquakes with several broadband stations to obtain improved source parameters

• Provide research data that will improve our understanding of the seismogenic crust which permits large earthquakes

• Provide near real-time notification to local, state and federal agencies, and to

• Archive and document the continuous data to permit future research.

Recent Efforts:

During 1999, we

• continued to add stations to the broadband network,

• overcame the August, 1999 GPS epoch problem that affected our timing by the purchase of new GPS receivers,

• upgraded data acquisition software which also addressed Y2K problems,

• implemented a data transfer mechanism that simultaneously transmits all signals to the NEIS of the U. S. Geological Survey so that they can enhance their capability for rapid earthquake location and notification in the CUSEC area. This proved valuable for the Kansas City event on May 13, 1999

Plans:

During 2000, we need to

• upgrade the broadband sensors at some stations

• harden our communication links, so that we can

• provide reliable automatic rapid earthquake location and notification for the region

• develop the capability to archive approximately 30Gb data annually.

Commitment

The function of the Saint Louis University Earthquake Center is to serve the public by providing basic information, the scientific community with quality data for research and government agencies with near real-time locations. A mechanism for providing this service is through use of the World Wide Web.

Further information on the broadband network, on reporting felt earthquakes or of recent earthquake recordings is available from the Saint Louis University Earthquake Center on the World Wide Web:

http://www.eas.slu.edu/Earthquake_Center/

or by Telephone: 314 977 2236.

R. B. Herrmann
B. J. Mitchell
Saint Louis University Earthquake Center