EARTHQUAKES, FAULTS, SUBSIDENCE AND LAND LOSS IN SOUTH LOUISIANA AND SOUTH TEXAS

"Unusual water disturbances" and seiches, with waves up to 2 m that occurred during a 30-minute period in confined streams and water bodies across South Louisiana and South Texas during the Alaskan earthquake of 27 March 1964, have now been correlated with regional listric growth faults. Although the faults are geologically old, tide gauge records and geomorphic signatures indicate that some, if not most, of the segments affected by the remote earthquake exhibited accelerated vertical movement during and after the event. Fault movement in turn, was a cause of twentieth century coastal land loss in the region.

Other remote earthquakes have caused seiches at some of the same locales as the 1964 Alaskan earthquake. Epicenters of historic local earthquakes also correlate with the listric growth faults.

Effects of shock waves from remote earthquakes, locations of local epicenters, and modern subsidence and land loss will be examined within the context of the linked regional tectonic framework.