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Seismic evidence for thermal runaway during intermediate‐depth earthquake rupture
Author(s) -
Prieto Germán A.,
Florez Manuel,
Barrett Sarah A.,
Beroza Gregory C.,
Pedraza Patricia,
Blanco Jose Faustino,
Poveda Esteban
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl058109
Subject(s) - thermal runaway , geology , intraplate earthquake , seismology , slow earthquake , interplate earthquake , foreshock , shear (geology) , deep focus earthquake , brittleness , geophysics , subduction , aftershock , petrology , materials science , tectonics , power (physics) , physics , battery (electricity) , quantum mechanics , composite material
Intermediate‐depth earthquakes occur at depths where temperatures and pressures exceed those at which brittle failure is expected. There are two leading candidates for the physical mechanism behind these earthquakes: dehydration embrittlement and self‐localizing thermal shear runaway. A complete energy budget for a range of earthquake sizes can help constrain whether either of these mechanisms might play a role in intermediate‐depth earthquake rupture. The combination of high stress drop and low radiation efficiency that we observe for M w 4–5 earthquakes in the Bucaramanga Nest implies a temperature increase of 600–1000°C for a centimeter‐scale layer during earthquake failure. This suggests that substantial shear heating, and possibly partial melting, occurs during intermediate‐depth earthquake failure. Our observations support thermal shear runaway as the mechanism for intermediate‐depth earthquakes, which would help explain differences in their behavior compared to shallow earthquakes.