Some like it hot: The spectrum of temperature rise during earthquakes

Abstract:

Temperature rise during an earthquake depends on shear stress, total slip and active width of the fault zone, all of which are important parameters necessary for more accurate rupture models. Here we describe the use of extractable organic molecules (biomarkers) for detecting earthquake slip in fault zones. By comparing the thermal maturity of biomarkers in fault zones to the thermal maturity in rocks immediately adjacent to the fault, we can determine if the fault has experienced significant frictional heating. We present results from a number of faults from different depths and tectonic environments, including the Japan Trench, the Punchbowl fault, CA, as well as several carbonate-bearing thrust and normal faults. Models that couple newly established thermal maturation kinetics with thermal diffusion in fault zones allow us to determine the maximum temperature achieved in each fault. Even the absence of a signal allows for a maximum slip event to be estimated, because of the limits placed on heating by the reaction kinetics. We discuss the range of maximum fault temperatures seen with this method to date, and discuss implications for estimates of frictional work and slip localization in fault zones.