Rapid Generation of Ground Motion Maps of the 8/17/99 Turkey and 9/20/99 Taiwan Earthquakes

Urs Group, Inc., Los Angeles CA

Investigators

Abstract

Abstract 9988879 The magnitude 7.4 Turkey earthquake of August 17, 1999 and the magnitude 7.6 Taiwan earthquake of September 20, 1999 were both widely recorded in the near fault region. Together, they provide an unprecedented opportunity to understand the nature of large earthquakes and their effects on the natural and built environment. Although most structures in the coastal regions of California are designed to withstand the ground motions form nearby earthquakes of magnitude larger than 7, there are practically no recordings of such earthquakes available for use in engineering analysis and design. The data from these two events have the potential to greatly enhance the ability to characterize reliably the ground motions that control the design of structures in seismically active regions. Due to the speed with which digital strong motion data are now available following a major earthquake, strong motion data were available to field reconnaissance teams when they visited Turkey and Taiwan, providing valuable guidance to engineers in their interpretation of the observed damage. The rapid availability of strong motion data also provides the ability, by means of ground motion maps, to characterize the strong ground motions at recording sites and throughout the regions affected by these earthquakes. The objective of this award is to support the development of these maps, based primarily on the recorded strong motion data. These ground motion maps will account for site conditions using available information on broad geological categories of site conditions, such as alluvium, soft rock, and hard rock. The parameters include peak acceleration, peak velocity, and 5% damped response spectral acceleration at periods of 0.3, 1.0, 2.0 and 4.0 seconds. These preliminary maps are refined using two methods of interpolating between recorded ground motions. These ground motion maps provide engineers with estimates of the ground motions experienced at specific sites, in order to interpret the causes of damage and failure observed in the reconnaissance investigations. These ground motion maps will be placed on the World Wide Web to provide rapid and broad access to this data by the earthquake engineering research community.