19 Quaternary Faulting Along the Northern Gulf of Mexico Margin

Tuesday, 29 March 2011
1:30 PM - 5:00 PM
D.H. Holmes C

EFFECTS OF THE 1964 ALASKAN EARTHQUAKE ON SOUTH LOUISIANA AND SOUTH TEXAS

Paper number: 19-6
Program: Theme Sessions
Time: 2:35 PM – 2:50 PM

Authors

Abstract

On March 27, 1964, unusual water seiches and felt effects occurred across the Northern Gulf region from the Chandeleur Islands, Louisiana to Freeport, Texas. These effects, chronicled on the front pages of the region’s newspapers, have been attributed to long-period surface shock waves from the magnitude 8.3 Prince William Sound, Alaska earthquake more than 3000 miles away. Re-evaluation of this event, which has attracted little attention from earth scientists, within the context of a revised regional structural model contributes significantly to understanding neotectonics in the Northern Gulf. The model relates distinctive geomorphic signatures of faults to known subsurface faults and fractures. Movements induced by the 1964 event identify live faults within the structural framework.

A series of 5 or 6 waves with peak-to-point amplitudes of one to two meters over a period of 20 to 30 minutes were reported at numerous locations including the Industrial Canal New Orleans, Krotz Springs, Golden Meadow, in Louisiana and Beaumont-Port Arthur, and Houston in Texas. Ocean going vessels were lifted and debris was churned from stream bottoms. Felt reports suggest that shock waves also triggered secondary earthquakes along local faults. A Rice University seismologist reported that Houston was lifted 10 cm as the gigantic surface wave passed through.

The 1964 event ushered in a period of accelerated fault movement, subsidence, and land loss in coastal Louisiana that peaked in the 1970s. Subsequent distant earthquakes such as the Denali, Alaska 2002 magnitude 7.9 event caused minor seiching in some of the 1964 locations.