The 2004 Mw 4.4 Rotenburg, Northern Germany, Earthquake and Its Possible Relationship with Gas Recovery

We study the 20 October 2004 Mw 4.4 Rotenburg (Wümme)/Neuenkirchen earthquake, located in a previously aseismic region in the northern German sedimentary basin. We constrain the source parameter by using different techniques. A possible relationship between this event, the regional tectonic setting, and local gas recovery is investigated. Different waveform in version and modelling approaches constrain the depth of the mainshock between 5 and 7 km. The source mechanism was oblique normal faulting on planes striking roughly north-south. An inversion for kinematics rupture parameters indicates a unilateral rupture propagation toward the north, consistent with the higher macroseismic intensities found toward the north in the region of Hamburg compared with those at a similar distance toward the south in the region of Hannover. Relocations of the mainshock and three of the largest aftershocks indicate that these events occurred within a few kilometres of three major gas fields and at depth close to gas production intervals. Comparison with seismicity triggered in the northern Netherlands by depletion of similar gas reservoirs in a similar tectonic environment suggests that the Mw 4.4 Rotenburg event may be related to gas recovery.