Source mechanism study of local earthquakes in Kuwait

Historically, Kuwait has relatively low seismicity; however, in recent years the Kuwait National Seismic Network (KNSN) has detected a significant number of local earthquakes. In 2015, two earthquakes-M_w 4.5 on 21 March 2015 and M_w 4.1 on 18 August 2015-were recorded by the KNSN and were widely felt across Kuwait. Most earthquakes happen in two areas close to the northern and southern oil/gas fields. The earthquakes are generally small (M_w < 5) and are shallow with focal depths of about 2-8 km. We determined the locations and source mechanisms of the largest two of these local earthquakes, using a Bayesian inversion method. Our results show that most likely these local earthquakes occurred on preexisting faults and may have been triggered by oil field activities. In Kuwait, where oil fields are close to populated areas, these induced earthquakes could produce ground accelerations high enough to cause damage to local structures built without using seismic design criteria.