Giant seismites and megablock uplift in the East African Rift: evidence for Late Pleistocene large magnitude earthquakes

Hilbert-Wolf, Hannah Louise, and Roberts, Eric M. (2015) Giant seismites and megablock uplift in the East African Rift: evidence for Late Pleistocene large magnitude earthquakes. PLoS ONE, 10 (6). pp. 1-18.

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Abstract

In lieu of comprehensive instrumental seismic monitoring, short historical records, and limited fault trench investigations for many seismically active areas, the sedimentary record provides important archives of seismicity in the form of preserved horizons of soft-sediment deformation features, termed seismites. Here we report on extensive seismites in the Late Quaternary-Recent (≤ ~ 28,000 years BP) alluvial and lacustrine strata of the Rukwa Rift Basin, a segment of the Western Branch of the East African Rift System. We document examples of the most highly deformed sediments in shallow, subsurface strata close to the regional capital of Mbeya, Tanzania. This includes a remarkable, clastic 'megablock complex' that preserves remobilized sediment below vertically displaced blocks of intact strata (megablocks), some in excess of 20 m-wide. Documentation of these seismites expands the database of seismogenic sedimentary structures, and attests to large magnitude, Late Pleistocene-Recent earthquakes along the Western Branch of the East African Rift System. Understanding how seismicity deforms near-surface sediments is critical for predicting and preparing for modern seismic hazards, especially along the East African Rift and other tectonically active, developing regions.

Item ID: 39234
Item Type: Article (Refereed Research - C1)
Keywords: seismite; Rukwa; sedimentology; rift; Africa; geology; earthquake
Additional Information:

© 2015 Hilbert-Wolf, Roberts. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

ISSN: 1932-6203
Funders: James Cook University, National Science Foundation (USA)
Projects and Grants: NSF-BCS- 127164, NSF-EAR-1349825
Date Deposited: 19 Jun 2015 03:20
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 70%
04 EARTH SCIENCES > 0403 Geology > 040313 Tectonics @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 70%
96 ENVIRONMENT > 9610 Natural Hazards > 961099 Natural Hazards not elsewhere classified @ 30%
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