Influence of anthropogenic groundwater pumping on the 2017 November 12 M7.3 Iran–Iraq border earthquake

Study of induced, triggered, stimulated and nuance earthquakes can provide a unique opportunity to probe into stress/frictional conditions on the subsurface fault. Although mechanism of faulting is tectonically driven phenomenon, anthropogenic crustal (un-)loading process can also drive long-term fault slip or modulate seismicity in the nearby seismogenic crust. Using Gravity Recovery and Climate Experiment data, surface subsidence rate captured by cGPS and 3-D hydrological stress models, we report that the 2017 November 12 M7.3 Iran–Iraq border earthquake in the Arabia–Eurasia collision boundary region of the Zagros fold-and-thrust belt was significantly influenced by the anthropogenic groundwater unloading in the Euphrates and Tigris River plains and western Iran, a region which is probably the most intensely irrigated region in the Middle East. We find that the anthropogenic crustal unloading contributed about one tenth of the secular interseismic stress change rate due to tectonic loading. Thus, the resulting cumulative stress accumulation was significantly influenced by the extensive groundwater pumping.