Fuentes-Figueroa, Zamara

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    Towards improvement of northeastern Caribbean tsunami hazard assessments - coring of coastal ponds yields seven events in a 5,000 year-old period
    (2018-06-01) Fuentes-Figueroa, Zamara; Schmidt, Wilford E.; College of Arts and Sciences - Sciences; Winter, Amos; Schizas, Nikolaos; Huérfano, Victor; Atwater, Brian; Department of Marine Sciences; López, Martha L.
    Current tsunami coastal hazard assessments in the northeastern Caribbean, limited by an uncertain interplate coupling and a short historic and paleoseismologic record, would benefit from ground truthing by means of detailed studies of the coastal sediment record. The northeastern Caribbean, surrounded by active faults, has experienced seven M 7.5 events in the last 500 years (1690, 1843, 1867, 1943, 1946, 1946, and 1974), of which five (1690, 1843, 1867, 1946, and 1946) generated tsunamis. Investigating the coastal sediment record requires differentiation between storm and tsunami overwash deposits. A post-storm survey of 2010 hurricane Earl described the effects on the coast of Anegada, British Virgin Islands, the island closest to the Puerto Rico Trench (PRT), as limited to wrack deposition along shores, deposition of an extensive microbial detritus coating from interior salt ponds and spillover fan deposits on the south shore that extended inland a few tens of meters. These effects contrasted significantly with two previously inferred pre-historic tsunami events (A.D. 1200-1450 and A.D. 1650-1800) characterized by underlying sand and shell sheet that extends 1.5 km southward from the north shore, large erosional features such as breached ridges and southward-strewn limestone boulders as far as 1 km inland. At St. Thomas, U.S. Virgin Islands, located southwest of Anegada and northwest of the 1867 tsunami source, seven tsunami deposits, from coastal ponds along the north and south coasts, are inferred from a 5,000 years old sediment record. Of these, one correlates to the AD 1650-1800 event, another to the AD 1200-1450, two occurred between 18 B.C.-A.D. 1151 and 351 B.C.-A.D. 129, another occurred between 1628-168 B.C. with the oldest recorded event exceeding 2901 B.C. Of these, two were found at three ponds and could be related to an event similar to that from A.D. 1200-1450. Most of these events were coincident with drastic environmental changes marked by sharp contacts, rip-up clasts, and lithological and ecological changes. These findings expand the tsunami record for the northeastern Caribbean to seven events within a 5,000-year time span. This work would benefit from additional dating of events to better constrain the time frame these events occurred and calculate a more precise recurrence rate for the region.
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    Towards improvement of northeastern Caribbean tsunami hazard assessments: Coring of coastal ponds yields seven events in a 5,000 year-old period
    (2018-05) Fuentes-Figueroa, Zamara; Schmidt, Wilford E.; College of Arts and Sciences - Sciences; Winter, Amos; Schizas, Nikolaos; Huérfano, Victor; Atwater, Brian; Otero, Ernesto; Department of Marine Sciences; López, Martha L.
    Current tsunami coastal hazard assessments in the northeastern Caribbean, limited by an uncertain interplate coupling and a short historic and paleoseismologic record, would benefit from ground truthing by means of detailed studies of the coastal sediment record. The northeastern Caribbean, surrounded by active faults, has experienced seven M 7.5 events in the last 500 years (1690, 1843, 1867, 1943, 1946, 1946, and 1974), of which five (1690, 1843, 1867, 1946, and 1946) generated tsunamis. Investigating the coastal sediment record requires differentiation between storm and tsunami overwash deposits. A post-storm survey of 2010 hurricane Earl described the effects on the coast of Anegada, British Virgin Islands, the island closest to the Puerto Rico Trench (PRT), as limited to wrack deposition along shores, deposition of an extensive microbial detritus coating from interior salt ponds and spillover fan deposits on the south shore that extended inland a few tens of meters. These effects contrasted significantly with two previously inferred pre-historic tsunami events (A.D. 1200-1450 and A.D. 1650-1800) characterized by underlying sand and shell sheet that extends 1.5 km southward from the north shore, large erosional features such as breached ridges and southward-strewn limestone boulders as far as 1 km inland. At St. Thomas, U.S. Virgin Islands, located southwest of Anegada and northwest of the 1867 tsunami source, seven tsunami deposits, from coastal ponds along the north and south coasts, are inferred from a 5,000 years old sediment record. Of these, one correlates to the AD 1650-1800 event, another to the AD 1200-1450, two occurred between 18 B.C.-A.D. 1151 and 351 B.C.-A.D. 129, another occurred between 1628-168 B.C. with the oldest recorded event exceeding 2901 B.C. Of these, two were found at three ponds and could be related to an event similar to that from A.D. 1200- 1450. Most of these events were coincident with drastic environmental changes marked by sharp contacts, rip-up clasts, and lithological and ecological changes. These findings expand the tsunami record for the northeastern Caribbean to seven events within a 5,000-year time span. This work would benefit from additional dating of events to better constrain the time frame these events occurred and calculate a more precise recurrence rate for the region.