A Near-Vertical Slab Tear in the Southeastern Solomon Islands

The southeastern part of the Solomon Islands, a highly seismically active area in the southern Pacific, experienced two moderate earthquakes (Mw 6.3 and 6.0) on January 27th and 29th, 2020. The regional seismic network, operational since October 2018, recorded the entire foreshock-main-shock-aftershock sequence, allowing for a new 1D velocity model and relocation of events. Based on the spacial distribution of the foreshock-aftershock sequence, together with focal mechanism data from the Global CMT database, we suggest that there is a near-vertical slab tear at the southern end of the South Solomon subducting slab, abutting a zone of strike-slip faulting that links it to the Vanuatu subduction zone to form a Subduction-Transform Edge Propagator fault. Our new data also indicates that a seismic gap occurs at depths from 25 to 35 km within the southern part of the South Solomon slab.