Crustal Heat Flow Drives the Earthquake Magnitude Distribution

Abstract Earthquake magnitude‐frequency distributions exhibit significant space‐time variations, which can provide critical insights into the physical processes driving seismicity. Understanding these variations is crucial for assessing seismic hazards and uncovering the physical processes driving earthquakes. One key parameter, the b ‐value, describes the relative proportion of small to large earthquakes and is thought to reflect factors such as stress conditions and fault properties. However, empirical evidence linking b ‐value variations to physical processes in real tectonic settings is still limited. Here, we show that b ‐value is systematically higher in regions with elevated heat flow, consistently across different tectonic settings and faulting style. This suggests that thermal conditions play a fundamental role in controlling earthquake size distributions, controlling the likelihood of large earthquakes in the different areas.