Sand Scripts of Past Tsunamis in Coastal Ponds of St. Thomas, U.S. Virgin Islands

Research Article| August 23, 2017 Sand Scripts of Past Tsunamis in Coastal Ponds of St. Thomas, U.S. Virgin Islands Zamara Fuentes; Zamara Fuentes aDepartment of Marine Sciences, University of Puerto Rico at Mayagüez, P.O. Box 9000, Mayagüez 00681, Puerto Rico, zamara.fuentes@gmail.com Search for other works by this author on: GSW Google Scholar Martitia P. Tuttle; Martitia P. Tuttle bM. Tuttle & Associates, P.O. Box 345, Georgetown, Maine 04548 U.S.A. Search for other works by this author on: GSW Google Scholar Wilford E. Schmidt Wilford E. Schmidt aDepartment of Marine Sciences, University of Puerto Rico at Mayagüez, P.O. Box 9000, Mayagüez 00681, Puerto Rico, zamara.fuentes@gmail.com Search for other works by this author on: GSW Google Scholar Author and Article Information Zamara Fuentes aDepartment of Marine Sciences, University of Puerto Rico at Mayagüez, P.O. Box 9000, Mayagüez 00681, Puerto Rico, zamara.fuentes@gmail.com Martitia P. Tuttle bM. Tuttle & Associates, P.O. Box 345, Georgetown, Maine 04548 U.S.A. Wilford E. Schmidt aDepartment of Marine Sciences, University of Puerto Rico at Mayagüez, P.O. Box 9000, Mayagüez 00681, Puerto Rico, zamara.fuentes@gmail.com Publisher: Seismological Society of America First Online: 15 Sep 2017 Online Issn: 1938-2057 Print Issn: 0895-0695 © Seismological Society of America Seismological Research Letters (2017) 88 (6): 1516–1526. https://doi.org/10.1785/0220170038 Article history First Online: 15 Sep 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Zamara Fuentes, Martitia P. Tuttle, Wilford E. Schmidt; Sand Scripts of Past Tsunamis in Coastal Ponds of St. Thomas, U.S. Virgin Islands. Seismological Research Letters 2017;; 88 (6): 1516–1526. doi: https://doi.org/10.1785/0220170038 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search ABSTRACT Five unusual overwash deposits within four coastal ponds and a mangrove site on St. Thomas, U.S. Virgin Islands, may be the telltale signs of tsunamis. The estimated ages and locations of the deposits suggest that the tsunamis originated from different offshore sources. These deposits were found during a reconnaissance‐level study on St. Thomas and adjacent cays located near the eastern end of the Greater Antilles volcanic arc, 60 km east of Puerto Rico and 150 km south of the Puerto Rico trench. The study sites occur within the narrow coastal zone in an otherwise high‐relief setting. The unusual deposits, distinct from the pond sediment, including six other overwash deposits similar to other known tsunami deposits, are composed of mixed lithic and carbonate sands, and hypersaline and marine shells, contain coral boulders and fragments, exhibit sharp or erosive lower contacts, and, in some cases, are capped by mud. Beach berms that front the sites are 1–2 m above mean sea level, composed of coral and lithic cobble‐size fragments as well as coarse, mixed‐composition sand, appear to be a source of the likely tsunami deposits. On the basis of sediment stratigraphy and radiocarbon dating, age estimates of the deposits suggest five tsunamis in the past 3000 years, two of which fall within date ranges of likely tsunami deposits identified on Anegada, British Virgin Islands, located 70 km northeast of St. Thomas. Findings of this reconnaissance‐level study suggest that the unusual overwash deposits on St. Thomas may be related to the 1867 tsunami triggered by an M∼7.3 earthquake in the Anegada Passage, the 1755 trans‐Atlantic tsunami triggered by the M 8.5 Lisbon earthquake, a tsunami between A.D. 1200 and 1450 first recognized on Anegada, extending its known area of impact farther to the southwest, and possibly two earlier events between 2000 and 3000+ years ago. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.