DEFINING THE HAZARD POSED BY EARTHQUAKES IN AFGHANISTAN

The international community is investing millions of dollars to reconstruct the infrastructure of Afghanistan, but the products of these efforts could be quickly destroyed by a major earthquake. Earthquakes and modern deformation in Afghanistan are caused by India subducting under Eurasia at a rate of about 40 mm/yr. This results in abundant destructive earthquakes and high hazard in eastern and northeastern Afghanistan and causes movement on the Chaman fault system, a major, continent-scale, sinistral-slip fault, and on related faults. Earthquakes and active faults are present in other parts of the country but the level of hazard is lower.

For the past three years, the USGS has taken a series of steps to evaluate Afghanistan's seismic hazards and to improve earthquake monitoring. To better characterize the hazard, the USGS has released a series of Open-File Reports: 1) a seismotectonic map (OFRs 2005-1265 and 2007-1104) showing key structural elements, 2) a comprehensive seismicity catalog containing more than 12,700 events (OFR 2006-1185), and 3) a map and database of probable and possible Quaternary faults (OFR 2007-1103). Information from these products is the foundation of a preliminary seismic-hazard map (OFR 2007-1137), which provides a scientific estimate of the frequency and strength of anticipated strong shaking in various parts of the country. The map is preliminary because it can be improved with better information on active faults, earthquake parameters, and attenuation relations.

We have also reestablished the Kabul (KBL) seismic station at Kabul University and integrated its real-time data into the Global Seismic Network. High-quality data from KBL allow us to determine the locations, magnitudes, and depths of earthquakes in the region more accurately and precisely. Collectively, these efforts allow us to better define the level of hazard nationwide, thus permitting the design of an earthquake-resistant infrastructure allowing reconstruction funds to be used prudently and effectively.