News Release

Seismology tip sheet from BSSA, August issue

Peer-Reviewed Publication

Seismological Society of America

Please cite the Bulletin of the Seismological Society of America (BSSA) as the source of this information. The Table of Contents is available upon request.

Limits on earthquake ruptures

New observations by scientists at University of Nevada, Reno suggest an upper limit of three on the number steps – jumps from one fault or fault segment to another -- through which an earthquake is likely to rupture. The number of ruptures is also observed to decrease as a function of the number of steps through which the respective earthquakes propagated.

These findings are particularly important for the development of seismic hazard maps of complex areas where there are overlapping fault segments. Significant uncertainty arises in estimating the length to which a rupture will propagate because historical earthquake ruptures have been observed to jump across discontinuities along fault strike and break more than one fault or fault segment in a single event.

This study of 22 historical strike-slip surface rupture earthquakes, combined with prior work, helps reduce uncertainties in estimating the size of earthquake ruptures in a system of mapped active faults.

The August 2011 issue of BSSA: "The length to which an earthquake will go to rupture," by Steven G. Wesnousky and Glenn P. Biasi at the University of Nevada, Reno.

Contact: Steven Wesnousky at or Glenn Biasi at

Seismic stations recorded explosion that sank South Korean vessel in 2010

Analysis of local seismic records suggest an explosion at shallow depth caused the sinking of the South Korean naval vessel, Cheonanham, near the border between North Korea and South Korea on March 26, 2010. Three plausible causes of the sinking were initially raised: an explosive source (torpedo or mine), shear breakage due to strain accumulation by fatigue and collision with a sunken rock.

Seismograms from three local stations recorded a seismic event, determined to be at the same time and location of the sinking vessel. Signatures suggesting detonation of an explosive source in the Yellow Sea are presented.

"Seismic investigation of the 26 March 2010 Sinking of the South Korean Naval Vessel Cheonanham" by Tae-Kyung Hong of Yonsei University, South Korea.


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