Maranhão earthquake of January 3, 2018 - a new GT5 event in the aseismic region of the Brazilian phanerozoic Parnaiba Basin

Abstract

Here it is presented the preliminary results of study, with local network, of the aftershock activity occurred in the aseismic region of Vargem Grande, Maranhão state, after a 4.6 mb mainshock on January 3, 2017. The focal mechanism solution indicates a strike slip fault with compression parallel to the cost line in agreement with previous studies. The aftershock activity was very intense in the begin fading to just few events after couple of days and the aftershock network only registered 60 events within two months. Hypocentral location of 10 events showed a possible trace of the fault in agreement with focal mechanism solution. The relocation of the main event with station correction and fixed depth was located within the aftershock cluster with accuracy of a GT5 event requirements.