Science
News: A new simulation may explain why fault segments that
are considered stable can sometimes rupture catastrophically.
Nadia Lapusta of Caltech and Hiroyuki Noda of the
Japan Agency for
MarineâEarth Science and Technology in
Yokohama created the simulation based on the properties of
borehole samples collected along a fault line in Taiwan.
Generally, stable faults are found where two tectonic plates
"creep" past each other steadily without building up much
strain. However, seismic activity on one segment of the fault
can generate enough heat to cause water in the ground to expand
into pores in the rocks of a nearby segment. As the water
pressure builds, it increases the strain of the tectonic plates
against each other until the fault ruptures. The model could
explain the magnitude-9 earthquake that struck off the east
coast of Japan in March 2011, although seismologists don't know
for certain whether the Tohoku fault was creeping or locked
prior to the quake.
