A 1000-yr-old tsunami in the Indian Ocean points to greater risk for East Africa

Thumbnail Image
Date
2020-05-12
Authors
Maselli, Vittorio
Oppo, Davide
Moore, Andrew L.
Gusman, Aditya Riadi
Mtelela, Cassy
Iacopini, David
Taviani, Marco
Mjema, Elinaza
Mulaya, Ernest
Che, Melody
Tomioka, Ai Lena
Mshiu, Elisante
Ortiz, Joseph D.
Alternative Title
Date Created
Location
DOI
10.1130/G47257.1
Replaces
Replaced By
Keywords
Abstract
The December 2004 Sumatra-Andaman tsunami prompted an unprecedented research effort to find ancient precursors and quantify the recurrence time of such a deadly natural disaster. This effort, however, has focused primarily along the northern and eastern Indian Ocean coastlines, in proximal areas hardest hit by the tsunami. No studies have been made to quantify the recurrence of tsunamis along the coastlines of the western Indian Ocean, leading to an underestimation of the tsunami risk in East Africa. Here, we document a 1000-yr-old sand layer hosting archaeological remains of an ancient coastal Swahili settlement in Tanzania. The sedimentary facies, grain-size distribution, and faunal assemblages indicate a tsunami wave as the most likely cause for the deposition of this sand layer. The tsunami in Tanzania is coeval with analogous deposits discovered at eastern Indian Ocean coastal sites. Numerical simulations of tsunami wave propagation indicate a megathrust earthquake generated by a large rupture of the Sumatra-Andaman subduction zone as the likely tsunami source. Our findings provide evidence that teletsunamis represent a serious threat to coastal societies along the western Indian Ocean, with implications for future tsunami hazard and risk assessments in East Africa.
Description
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Maselli, V., Oppo, D., Moore, A. L., Gusman, A. R., Mtelela, C., Iacopini, D., Taviani, M., Mjema, E., Mulaya, E., Che, M., Tomioka, A. L., Mshiu, E., & Ortiz, J. D. A 1000-yr-old tsunami in the Indian Ocean points to greater risk for East Africa. Geology, 48(8), (2020): 808-813, doi:10.1130/G47257.1.
Embargo Date
Citation
Maselli, V., Oppo, D., Moore, A. L., Gusman, A. R., Mtelela, C., Iacopini, D., Taviani, M., Mjema, E., Mulaya, E., Che, M., Tomioka, A. L., Mshiu, E., & Ortiz, J. D. (2020). A 1000-yr-old tsunami in the Indian Ocean points to greater risk for East Africa. Geology, 48(8), 808-813.
Cruises
Cruise ID
Cruise DOI
Vessel Name
Collections
Except where otherwise noted, this item's license is described as Attribution 4.0 International