Strong-motion Seismology, Site Response & Ground Motion

Intense ground shaking during large earthquakes can damage or even cause failure of engineered structures such as buildings, bridges, highways, and dams. Sustained strong shaking can also trigger ground failures, such as rock falls, landslides, earth flows and liquefaction. Strong motion seismology uses special sensors, called accelerometers, to record these large-amplitude ground motions and the response of engineered structures to these motions.Recordings of large-amplitude seismic waves near the earthquake source can be used to investigate the fault motions that produced the earthquake.

Site response and ground motion studies use standard seismometers and oil-industry standard geophones to measure the local shaking from natural and man-made sources. These measurements help predict differential, site-dependent ground motion resulting from earthquakes.This information is used to upgrade building codes, to design earthquake-resistant structures, and to predict the patterns of strong shaking from future large earthquakes. Rapid reporting of shaking levels also helps to focus emergency response efforts in areas where damage is likely to be the greatest.

• Cone Penetration Testing

• GEOS Home Page

  Reports and downloadable data from the USGS General Earthquake Observation System for nav-selected significant earthquakes since 1975, and for long- and short-term deployments.

• Ground Motion Studies

  Field response to damaging earthquakes, operation of dense seismic arrays and modeling of intense ground shaking are some of the responsibilities of this program.

• Memphis, TN Urban Hazard Mapping Project

  Download maps of earthquake ground shaking at a scale appropriate for urban planning and development, disaster mitigation and response planning. These account for local variations in soils and their effects on shaking. Raw data and posters also available.

• Predicted Shaking for a Repeat of the Great 1906 Earthquake

  Automated slide show (15 minutes) reviewing the 1906 and 1989 earthquake damage, the application of GIS technology, and expected ground shaking maps for the San Francisco Bay Region.

• Scientific Investigations in the Pacific Northwest

  Shear velocity measurements in downtown Seattle are helping modelers predict damaging groundmotion from earthquakes.

• Site Response in the Northern San Francisco Bay Area, CA