Tuesday, November 28, 2006
Predicting Endpoint Of Earthquake Ruptures
Reno (USA), 27 November: A study of 22 historical strike-slip earthquakes has revealed new insights into how an earthquake propagates along a fault and where the end point of a future earthquake rupture is likely to occur. The study, compiled by Steven Wesnousky, is published in this week’s Nature.
Earthquake faults are made up of lots of differently sized segments or ‘steps’, so that when an earthquake occurs, the rupture trace is often discontinuous. The length of an earthquake rupture along the fault will therefore depend on how much stress builds up at the junctions between these fault segments.
Wesnousky studied maps of historical strike-slip earthquakes such as the 1992 Landers quake in California and the 1999 Izmit quake in Turkey. The rupture lengths of these earthquakes ranged from 10 to 420 km. He found that two-thirds of the endpoints of strike-slip earthquake ruptures are associated with these fault steps or with the ends of active fault traces. There appears to be a critical distance of fault step- 3 to 4 km- above which earthquake ruptures do not propagate, and below which rupture propagation ceases only 40% of the time. This limiting dimension observed also seems to be largely independent of the total length of the fault.
The results from this study may be of practical importance in assessing seismic hazards along a fault and how far any future earthquake is likely to propagate along it.
(ResearchSEA)
Earthquake faults are made up of lots of differently sized segments or ‘steps’, so that when an earthquake occurs, the rupture trace is often discontinuous. The length of an earthquake rupture along the fault will therefore depend on how much stress builds up at the junctions between these fault segments.
Wesnousky studied maps of historical strike-slip earthquakes such as the 1992 Landers quake in California and the 1999 Izmit quake in Turkey. The rupture lengths of these earthquakes ranged from 10 to 420 km. He found that two-thirds of the endpoints of strike-slip earthquake ruptures are associated with these fault steps or with the ends of active fault traces. There appears to be a critical distance of fault step- 3 to 4 km- above which earthquake ruptures do not propagate, and below which rupture propagation ceases only 40% of the time. This limiting dimension observed also seems to be largely independent of the total length of the fault.
The results from this study may be of practical importance in assessing seismic hazards along a fault and how far any future earthquake is likely to propagate along it.
(ResearchSEA)
# posted by mediabhartiwebsolutions @ 4:23 AM 
Subscribe to Posts [Atom]