Seismic gap: Difference between revisions

Content deleted Content added

Inline

Revision as of 09:25, 28 September 2009

A seismic gap is a segment of an active fault that has not slipped in an unusually long time when compared with other segments along the same structure. Seismic gap hypothesis/theory states that, over long periods of time, the displacement on any segment must be equal to that experienced by all the other parts of the fault.^[1] Any large and longstanding gap is therefore considered to be the fault segment most likely to suffer future earthquakes.

The applicability of this approach has been criticised by some seismologists^[2], although it has been used successfully in some areas (see examples below).

Examples

Loma Prieta Seismic Gap, Cali'Bold text''''Bold text''''Bold text'Bold text'''''''fornia

Prior to the 1989 Loma Prieta earthquake, that segment of the San Andreas fault system recorded much less seismic activity than other parts of the fault. ^[3] The main shock and aftershocks of the 1989 event occurred within the previous seismic gap.

Central Kuril gap, Russia

Immediately following the 2004 Indian Ocean earthquake, a seismic gap analysis of the seismic zones around the Pacific Ocean identified the Central Kuril segment of the Kuril-Kamchatka Trench subduction zone as the most likely to give rise to a major earthquake.^[4] This zone, 500 km in length, at that time had experienced no major earthquake since 1780, but was bounded to north and south by segments that had moved within the last 100 years. The M_w = 8.3 earthquake of 15 November 2006 and the M_w = 8.2 earthquake of 13 January 2007 occurred within the defined gap.

References

External links

USGS glossary entry

This tectonics article is a stub. You can help Wikipedia by expanding it.

[1] McCann, W.R., Nishenko, S.P., Sykes, I.R. & Krause, J. 1979. Seismic gaps and plate tectonics: seismic potential for major boundaries. Pure and applied geophysics, 117, 1082-1147

[2] Kagan, Y.K. & Jackson, D.D. 1991. Seismic Gap Hypothesis: Ten Years After. Journal of Geophysical Research, 96(B13), 21,419-21,431

[3] Lessons Learned from the Loma Prieta, California, Earthquake of October 17, 1989. U.S.G.S. Circular 1045 N.B. requires free ie djvu plug-in to view

[4] Baranov, B., Lobkovsky, L., Ivaschenko, A., Kulinich, R. & B. Karp, B. 2007. The Central Kuril Earthquakes and Tsunamis of 15 November 2006 and 13 January 2007: Findings of a Pre-event geophysical field survey. EGU Abstracts

[1]

[2]

[3]

[4]

@@ Line 5: / Line 5: @@
 ==Examples==
 [[Image:USGS 1045 Fig5.jpg|right|400px|thumb|Cross sections along the San Andreas fault showing recorded seismic activity A) 20 years before the Loma Prieta event, B) The main shock (large circle) and aftershocks for the Loma Prieta event, USGS Circular 1045]]
-===Loma Prieta Seismic Gap, California===
+===Loma Prieta Seismic Gap, Cali''''''Bold text'''''''''Bold text'''''''''Bold text''''''Bold text''''''''''''fornia===
 Prior to the [[1989 Loma Prieta earthquake]], that segment of the [[San Andreas fault]] system recorded much less seismic activity than other parts of the fault. <ref>[http://pubs.er.usgs.gov/djvu/CIR/circ_1045.djvu Lessons Learned from the Loma Prieta, California, Earthquake of October 17, 1989. U.S.G.S. Circular 1045 ''N.B. requires free ie  djvu plug-in to view'']</ref> The main shock and [[aftershock]]s of the 1989 event occurred within the previous seismic gap.