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The development of multiple paleotemperature proxies over the last twenty years has led to an increasing number of coseismic temperature measurements collected across a variety of faults. Here we present the first compilation of coseismic temperature rise measurements and frictional energy estimates to investigate the contribution of frictional heating to the earthquake energy budget and how this varies over different fault and earthquake properties. This compilation demonstrates that there is no clear relationship between coseismic temperature and displacement or thickness of the principal slip zone. Coseismic temperature rise increases with the depth of faulting until ~5 km and below this depth temperature rise remains relatively constant. Frictional energy, similarly, increases with depth until ~5km. However, frictional energy is remarkably similar across all of the faults studied here, with most falling below 45 MJ/m2. Our results suggest that dynamic weakening mechanisms may limit frictional energy during coseismic slip. We also demonstrate a basic difference between small and large earthquakes by comparing frictional energy to other components of the earthquake energy budget. The energy budget for small earthquakes (<1-10 m of displacement) is dominated by frictional energy, while in large events (>1-10 m of displacement), frictional, radiated, and fracture energy contribute somewhat equally to the earthquake energy budget. 

Abstract Creeping faults are difficult to assess for seismic hazard because they may participate in rupture even though they likely cannot nucleate large earthquakes. The creeping central section of the San Andreas fault in California (USA) has not participated in a historical large earthquake; however, earthquake ruptures nucleating in the locked northern and southern sections may propagate through the creeping section. We used biomarker thermal maturity and K/Ar dating on samples from the San Andreas Fault Observatory at Depth to look for evidence of earthquakes. Biomarkers show evidence of many earthquakes with displacements >1.5 m in and near a 3.5-m-wide patch of the fault. We show that K/Ar ages decrease with thermal maturity, and partial resetting occurs during coseismic heating. Therefore, measured ages provide a maximum constraint on earthquake age, and the youngest earthquakes here are younger than 3 Ma. Our results demonstrate that creeping faults may host large earthquakes over longer time scales.