Oral Presentation

MECHANICS OF INTRAPLATE EARTHQUAKES

Pradeep Talwani and Abhijit Gangopadhyay, Department of Geological Sciences, University of South Carolina, 701 Sumter Street, EWSC Room #517, Columbia, South Carolina, 29208, ( Email: talwani@prithvi.seis.sc.edu).

Any model proposed to explain large earthquakes in Stable Continental Regions (SCR) must satisfy the following constraints. i. Two or three large earthquakes that occur in a short period of time in a region of low strain rate, ii. there is an absence of large surface manifestations of strain accumulation and iii. the strain is localized in a local, small volume (compared to the plate boundary). We propose the following testable schematic model. Within the SCR, rift basins provide locations of localized weakness, within these, the presence of stress concentrators such as intersecting faults, buried igneous bodies, rift pillows (among other causes) produce a region where the application of plate tectonic stresses results in an anomously stressed volume, with localized pockets of high strain accumulation and earthquakes. We test this model with seismicity, geophysical and geodetic data from the New Madrid, Charleston and other seismic zones.