Mud volcano response to the 4 April 2010 El Mayor‐Cucapah earthquake

[1] Mud volcanoes sometimes respond to earthquakes, but the mechanisms by which earthquakes trigger changes in ongoing eruptions or initiate new eruptions are not completely understood. We measured gas discharge at a field of mud volcanoes near the Salton Sea, southern California, before and after the 4 April 2010 El Mayor‐Cucapah earthquake and observed an increase in gas flux immediately following the earthquake and a subsequent recovery to pre‐earthquake values. This earthquake‐eruption pair is of particular interest because the earthquake produced large strains, up to 1.2%, near the mud volcano location, allowing us to test two competing triggering mechanisms: (1) shaking‐ induced bubble mobilization and (2) permeability enhancement. We measured the rheology of erupted mud from the mud volcanoes to quantify the importance of mechanism 1 and found that this mechanism is unlikely to be important. We therefore favor the explanation that the increased gas flux was caused by a transient increase in permeability.