Bulletin of the Seismological Society of America
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Bulletin of the Seismological Society of America; January 2007; v. 97; no. 1A; p. S279-S295; DOI: 10.1785/0120050617
© 2007 Seismological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Stein, S.
Right arrow Articles by Okal, E. A.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Ultralong Period Seismic Study of the December 2004 Indian Ocean Earthquake and Implications for Regional Tectonics and the Subduction Process

Seth Stein1 and Emile A. Okal1

1 Department of Geological Sciences
Northwestern University
Evanston, Illinois 60208

Analysis of the earth’s longest period normal modes shows that the December 2004 Sumatra–Andaman earthquake was much larger (Mw 9.3) than initially inferred from surface-wave data and involved slip on a much longer fault than initially inferred from body-wave data. The seismic moment and relative excitation of the normal modes indicate that the entire aftershock zone ruptured, consistent with the large tsunami amplitudes in Thailand, Sri Lanka, and India. An apparent increase in seismic moment with period results from interference between parts of the fault. The earthquake resulted from subduction of the Indian plate beneath the Burma microplate, a sliver plate between the Indian and Sunda plates. Hence, the rate and direction of convergence depends on the motion of the Burma plate, which is not well known. Convergence would be highly oblique if the rate of motion between Burma and Sunda is that inferred from spreading in the Andaman Sea, and less if a slower rate is inferred from the Sagaing fault. The December earthquake was much larger than expected from a previously proposed relation, based on the idea of seismic coupling, in which such earthquakes occur only when young lithosphere subducts rapidly. Moreover, a global reanalysis finds little support for this correlation. Hence, we suspect that much of the apparent differences between subduction zones, such as some trench segments but not others being prone to Mw >8.5 events and hence oceanwide tsunamis, may reflect the short earthquake history sampled. This possibility is supported by the variability in rupture mode at individual trench segments.




This article has been cited by other articles:


Home page
 GeologyHome page
R. McCaffrey
Global frequency of magnitude 9 earthquakes
Geology, March 1, 2008; 36(3): 263 - 266.
[Abstract] [Full Text] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
S. L. Bilek, K. Satake, and K. Sieh
Introduction to the Special Issue on the 2004 Sumatra-Andaman Earthquake and the Indian Ocean Tsunami
Bulletin of the Seismological Society of America, January 1, 2007; 97(1A): S1 - S5.
[Full Text] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
S. Lambotte, L. Rivera, and J. Hinderer
Constraining the Overall Kinematics of the 2004 Sumatra and the 2005 Nias Earthquakes Using the Earth's Gravest Free Oscillations
Bulletin of the Seismological Society of America, January 1, 2007; 97(1A): S128 - S138.
[Abstract] [Full Text] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
T. Seno and K. Hirata
Did the 2004 Sumatra-Andaman Earthquake Involve a Component of Tsunami Earthquakes?
Bulletin of the Seismological Society of America, January 1, 2007; 97(1A): S296 - S306.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2007 by the Seismological Society of America.