PNSN Strong Motion Network PNSN > Strong Motion > Overview

1. Introduction

The Pacific Northwest Seismograph Network is continuing to expand the network of modern, digital, strong-motion instrumentation. These are distributed through the populated areas of Washington and Oregon. All strong motion sites have 3-component accelerometers and several sites also have 3-component broadband velocity seismometers. All sites provide real-time digital data telemetered to the network center at the University of Washington.

These data are currently used for

• accurate determination of earthquake locations and magnitudes
• rapid automated computation of ground motion parametric data (eg, peak acceleration)
• collection of on-scale digital waveform data from large earthquakes
• generation of ShakeMaps.

With accelerometers that can record up to 2 g these instruments can record ground motions from large earthquakes without waveform distortion. Parametric data, such as peak acceleration and spectral intensity, are computed and made available on PNSN Web pages within several hours of significant earthquakes. ShakeMap capabilities were implemented in 2001.

The combination of broadband seismometers and high dynamic range strong-motion accelerometers make it possible to compute engineering parameters for earthquakes as small as magnitude 2.5 in the Puget Sound urban area. The archived waveform data can also be used in studies of site response.

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Updated August 13, 2002