Overview
- A M7.4 mainshock near Ciudad Hidalgo on July 17 set off a prolonged aftershock sequence that had exceeded 1,000 events through July 26, with a M6.5 recorded as the largest aftershock.
- The Servicio Sismológico Nacional recorded a M5.9 late Monday, July 27, with an epicenter about 87 km southwest of Ciudad Hidalgo and a shallow focal depth of roughly 10 km.
- Additional shallow, moderate shocks were logged overnight into July 28, including M4.2–M4.4 events at distances between about 106 km and 157 km from Ciudad Hidalgo and focal depths near 6–16 km.
- Authorities report no major structural damage or injuries so far, and state and municipal Protección Civil units are conducting field inspections and urging residents to check buildings and emergency plans.
- Scientists say the Chiapas coast is highly seismically active because of Cocos-plate subduction, that aftershock rates normally taper over time, and that continuous SSN/UNAM monitoring will guide further safety actions.