Overview

• USGS listed 22 earthquakes of magnitude 2.5 or greater in the North America–Caribbean region over the 24 hours to August 29.
• The latest USGS updates included a magnitude 5.5 event west of Adak, Alaska, and a sequence near Valmy, Nevada, with quakes up to magnitude 3.6.
• Mexico’s SSN reported a magnitude 4.0 quake at 00:03 on August 28 located 62 km northwest of Cintalapa, Chiapas, at 133 km depth with no damage reported.
• SASMEX did not activate for the Chiapas event because its magnitude and distance did not meet the system’s thresholds, which require roughly magnitude 6 beyond 350 km, magnitude 5 between 250–350 km, or above magnitude 5 within 250 km.
• UNAM and SSN note Mexico straddles several tectonic plates and records more than 15,000 earthquakes annually, most too small to cause damage but continuously monitored by authorities.