Overview

• Mexico’s national seismic service confirmed a magnitude 4.1 earthquake at 05:12 on October 1 with an epicenter southwest of Mapastepec, Chiapas at a depth of about 4.9 km.
• SASMEX did not issue a public alarm because activation is based on combined distance and magnitude criteria rather than whether a quake is felt.
• According to published criteria, alerts generally require magnitude 6 for epicenters beyond 350 km, magnitude 5 for 250–350 km, and stronger magnitudes for events closer than 250 km.
• USGS data show 15 earthquakes of magnitude greater than 2.5 across North America and the Caribbean in the past 24 hours, reflecting routine regional seismicity.
• USGS recorded a magnitude 4.0 event south-southeast of Sand Point, Alaska at 07:22 UTC and noted a magnitude 3.3 as the strongest in the continental U.S. near Malaga, New Mexico.