Penn Arts & Sciences Logo

Stratigraphic evidence for an early Holocene earthquake in Aceh, Indonesia

Authors: 
Pre, C. A. G., Horton, B. P., Kelsey, H. M., Rubin, C. M., Hawkes, A. D., Daryono, M. R., Rosenberg, G., Culver, S. J.
Year: 
2 012
Source: 
Quaternary Science Reviews
Abstract: 
The Holocene stratigraphy of the coastal plain of the Aceh Province of Sumatra contains 6 m of sediment with three regionally consistent buried soils above pre-Quaternary bedrock or pre-Holocene unconsolidated sediment. Litho-, bio-, and chronostratigraphic analyses of the lower buried soil reveals a rapid change in relative sea-level caused by coseismic subsidence during an early Holocene megathrust earthquake. Evidence for paleoseismic subsidence is preserved as a buried mangrove soil, dominated by a pollen assemblage of Rhizophora and/or Bruguiera/Ceriops taxa. The soil is abruptly overlain by a thin tsunami sand. The sand contains mixed pollen and abraded foraminiferal assemblages of both offshore and onshore environments. The tsunami sand grades upward into mud that contains both well-preserved foraminifera of intertidal origin and individuals of the gastropod Cerithidea cingulata. Radiocarbon ages from the pre- and post-seismic sedimentary sequences constrain the paleoearthquake to 6500-7000 cal. yrs. BP. We use micro-and macrofossil data to determine the local paleoenvironment before and after the earthquake. We estimate coseismic subsidence to be 0.45 +/- 0.30 m, which is comparable to the 0.6 m of subsidence observed during the 2004 Aceh-Andaman earthquake on Aceh's west coast. (C) 2012 Elsevier Ltd. All rights reserved.
EES Authors: 
Candace Grand Pre (2011)
Andrea Hawkes (2008)

Department of Earth and Environmental Science / University of Pennsylvania, 251 Hayden Hall, 240 South 33rd Street, Philadelphia, PA 19104-6316