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Searching for the Blind Fault: Haiti Subsurface Imaging Project

Kocel Eray, Robert R. Stewart, and Paul Mann
University of Houston

The Haiti earthquake of 12 January, 2010 was initially reported to have occurred along the main strike slip fault (Enriquillo–Plantain Garden fault zone, EPGFZ), but more recent studies proposed slips on previously unrecognized, neighboring faults (Léogâne). As a participant in SEG’s Geoscientists Without Border program, we have investigated the shallow subsurface at Léogâne Fan Delta, Haiti using seismic and gravity techniques. The main purpose of this project are: characterization and analyses of subsurface structure and associated hazards, characterizing near-surface sediments physical properties, finding and understanding the blind faults that are thought to have given rise to the 2010 earthquake (Léogâne fault). The CMP stacked section shows multiple discontinuity profile whose location coincides with the anomalies observed at P and S wave refraction velocity profile. Extracted reflection coefficients also support a reflective structure at these offsets. We interpret the anomalous structure as North dipping thrust fault (approximately at 60°). Near-surface reflection seismic analysis provided deeper information indicating multiple layers with varying velocities, intersected by a number of faults. The estimated Free-air gravity profile suggests that the variation of the gravitational field may be related with the proposed faults. We expect to conduct more extensive surveys during January, 2014.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013