LEARNING FROM HURRICANE IRMA, DIFFERENTIATING TSUNAMI FROM HURRICANE DEPOSITS, AND RE-EVALUATING POSSIBLE TSUNAMI DEPOSITS ON ST. THOMAS, US VIRGIN ISLANDS Final Technical Report Research supported by the U.S. Geological Survey (USGS), Department of the Interior, under USGS Grant No. G19AP00101 Principal Investigator, Martitia P. Tuttle Co-Principal Investigator, Zamara Fuentes M. Tuttle & Associates P.O. Box 345 Georgetown, ME 04548 Tel: 207-371-2007 E-mail:
[email protected] URL: http://www.mptuttle.com Project Period: 8/1/2019-3/31/2021 Program Element I: Regional Earthquake Hazards Assessments Key Words: Paleoseismology, Tsunami Geology, Age Dating The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. LEARNING FROM HURRICANE IRMA, DIFFERENTIATING TSUNAMI FROM HURRICANE DEPOSITS, AND RE-EVALUATING POSSIBLE TSUNAMI DEPOSITS ON ST. THOMAS, US VIRGIN ISLANDS Principal Investigator Martitia P. Tuttle Co-Principal Investigator Zamara Fuentes M. Tuttle & Associates P.O. Box 345 Georgetown, ME 04548 Telephone: (207) 371-2007 E-mail:
[email protected] ABSTRACT Overwash deposits resulting from Hurricane Irma’s storm surge formed at five coastal study sites but only extended into Saba Pond on Saba Islet ~4.5 km south of St. Thomas. At Magens Bay, overwash deposits extended inland along a stream and probably into a ponded area, but the area was inaccessible due to debris from damaged mangroves. At Cabrita Pond on the northeast coast, two overwash fans composed primarily of lithic and carbonate cobbles reached the pond’s edge but otherwise did not contribute to the pond bottom sediment.