Induced Earthquakes in the Southern Delaware Basin, Texas, Are Bound by a Geomechanically Controlled Maximum Magnitude

In this paper we document the first example-the southern Delaware Basin-where widespread induced triggered (as opposed to “driven”) seismicity across a large area exhibits a maximum magnitude truncation. The most likely cause of this truncation is that although the shallow faults in this area are many km in length, they are structurally constrained and have limited down-dip widths, typically no more than approximately 1 km. Ruptures on faults of such limited width are not expected to attain high aspect ratios. As such, the ruptures on such faults would be limited to dimensions of roughly 1 km², which corresponds to magnitudes which closely match the observed M_MAX truncation. The M_MAX truncation for induced earthquakes in the southern Delaware Basin has significant implications since it implies that down-dip fault widths may play an important role in constraining the maximum magnitudes of induced events.