The May 2016 Mw 5.6 Earthquake at Rivera Fault Zone

On May 7, an earthquake with MW = 5.6 took place in the contact area of the Rivera Plate, Cocos Plate and the Middle America Trench, subsequently occurred a seismic sequence with over 200 earthquakes until May 16.

This seismic sequence was studied from the data collected during the TsuJal project. Between April and November 2016, seismic stations were recording onshore and offshore the passive seismicity in the area of Rivera Plate and Jalisco Block. The temporary seismic network (TSN) consisted of 25 Obsidian stations with a LE-3D MkIII sensor from the northern part of the state of Nayarit to the southern part of the state of Colima, including the Islas Marías. This network complemented the Jalisco Seismic Accelerometric Telemetric Network (RESAJ) reaching a total of 50 seismic stations deployed on land. In the offshore region, ten Ocean Bottom Seismometers (OBS) type LC2000SP with three short-term seismic and one pressure sensors were deployed by BO El Puma (UNAM) from the Islas Marías to the border between the states of Colima and Michoacán.

The USGS located this seismic sequence north of the Rivera Fault Zone (RFZ) near the Mesoamerican Trench, while the locations obtained from the OBS network located it about 50 km south between the RFZ and the East Pacific Rise. Besides, the USGS reported a strike-slip fault focal mechanism, while our studies indicate a focal mechanism of thrust failure.

In this work, an analysis of this sequence with 87 earthquakes occurred between May 7 and 11, 2016, recorded by three local seismic networks (RESAJ, TSN, and OBS) is presented.