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Published January 10, 1999 | Published
Journal Article Open

Submergence and uplift associated with the giant 1833 Sumatran subduction earthquake: Evidence from coral microatolls

Abstract

The giant Sumatran subduction earthquake of 1833 appears as a large emergence event in fossil coral microatolls on the reefs of Sumatra's outer-arc ridge. Stratigraphic analysis of these and living microatolls nearby allow us to estimate that 1833 emergence increased trenchward from about 1 to 2 m. This pattern and magnitude of uplift are consistent with about 13 m of slip on the subduction interface and suggest a magnitude (M_w) of 8.8–9.2 for the earthquake. The fossil microatolls also record rapid submergence in the decades prior to the earthquake, with rates increasing trenchward from 5 to 11 mm/yr. Living microatolls show similar rates and a similar pattern. The fossil microatolls also record at least two less extensive emergence events in the decades prior to 1833. These observations show that coral microatolls can be useful paleoseismic and paleogeodetic instruments in convergent tectonic environments.

Additional Information

© 1999 American Geophysical Union. Received 26 January 1998; accepted 6 October 1998. This work has been supported by NSF grants NSF EAR-9406781, NSF EAR 9405870, and NSF EAR 9607120. We greatly appreciated the technical assistance of Anto Sanyoto and Suyatno in the field and the skills of the captain and crew of our research vessel, the Dani Putra. We also wish to thank Hery Harjono for his help in steering us through administrative procedures, John Hoff and Hai Cheng for help with the geochemical analyses Anne Lilje and Tony Soeller for assistance with maps, and Tim Melbourne for the computer code to model displacement. We benefited from the thorough reviews of the manuscript by Robert McCaffrey, Yehuda Bock, and Joseph Curray. Caltech Seismological Laboratory contribution 8502.

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