HR: 1340h
AN: T13C-1484    [Abstracts]
TI: Tsunami Hazard for the Bay of Honduras Posed by Roatan Island Faulting
AU: * Cox, R T
EM: randycox@memphis.edu
AF: Earth Sciences, Johnson Hall, Room G1 University of Memphis, Memphis, TN 38152, United States
AU: Lumsden, D N
EM: dlumsden@memphis.edu
AF: Earth Sciences, Johnson Hall, Room G1 University of Memphis, Memphis, TN 38152, United States
AU: Talnagi, J
EM: talnagi.1@osu.edu
AF: Nuclear Reactor Lab, Ohio State University 1298 Kinnear Rd., Columbus, OH 43212, United States
AU: Gough, K
EM: kgough@memphis.edu
AF: Earth Sciences, Johnson Hall, Room G1 University of Memphis, Memphis, TN 38152, United States
AB: Uplifted and warped coastal landforms (fossil coral reef and beachrock, wave-cut and beach terraces) on the western part of Roatan Island off the northern Honduran coast record at least two late Holocene earthquakes that we estimate to have been >M7. Uplift has been primarily across a fault following the south coast of western Roatan, herein termed the "Flowers Bay fault". We constrain the ages of the displaced landforms with ESR and radiocarbon dates of carbonate and a sea level elevation curve compatible with Caribbean data. The fossil reef grew between 37 and 34 Ka, and the beachrock horizon and lowest terrace developed between 1700 and 1000 AD. One earthquake that raised the south coast up to 5 m post-dates 1700 AD. We interpret this event as the great earthquake of August 1856 off the northern Honduran coast that generated a tsunami that ran as much as 24 km onto the mainland. Another prehistoric earthquake circa 900 AD caused similar vertical displacement as the later event and likely generated an equivalent tsunami. The age and elevation of the fossil reef require an average uplift rate of 3 mm/yr, consistent with a recurrence interval of ~1000 years for these large earthquakes.
DE: 8010 Fractures and faults
DE: 8036 Paleoseismology (7221)
DE: 8150 Plate boundary: general (3040)
DE: 9360 South America
SC: Tectonophysics [T]
MN: 2007 Fall Meeting