Historical Seismicity of Texas--A Summary: ABSTRACT

Abstract

A survey of the historical seismicity of Texas revealed more than 100 earthquakes of magnitude 3 or greater from February 1847 to December 1984. Of these, 82 earthquakes are known to have been felt, and 24 events are associated with reports of damage. The largest earthquake (magnitude = 5.9) occurred on August 16, 1931, near the town of Valentine in west Texas. Many buildings were damaged in the epicentral area, and the total felt area exceeded 1 million km2. Earthquakes in the Valentine area, as well as other events farther west near El Paso, are probably related to the Rio Grande rift system. Several large events in the Texas Panhandle may be associated with a zone of crustal weakness that follows the trend of the Amarillo uplift. Earthquakes in eastern Texas are associated with several fault systems in the Gulf coastal plain. A large earthquake on October 22, 1882, had previously been located in northeast Texas near the town of Paris; however, a reevaluation of the intensities suggests the epicenter was probably farther north in Oklahoma. Several other events in previous catalogs have been discarded or relocated. More recent Texas earthquakes may have been induced by oil field operations. Seismic activity in west Texas near the towns of Kermit and Snyder are probably caused by waterflooding projects. Several recent earthquakes in the Gulf coastal plain may be associated with fluid withdrawal from oil and gas fields in up-to-the-coast normal faults. End_of_Article - Last_Page 1419------------