MEXICO CITY, July 25 — A magnitude 5.1 earthquake struck 43 kilometres southwest of Puerto Madero, Mexico, at 05:26 UTC on July 25, according to the U.S. Geological Survey (USGS). The quake occurred at a depth of 35 kilometres. The USGS detected the event through its real-time global seismic monitoring network.
No tsunami warning was issued. At least six people reported feeling the quake.
The epicentre was offshore, southwest of Puerto Madero, a coastal town on the Pacific side of Chiapas.
Shallow Depth, Moderate Punch
The depth of 35 kilometres is notable. Shallow earthquakes — those less than 70 km deep — typically produce stronger shaking at the surface than deeper events of the same magnitude. A magnitude 5.1 earthquake is classified as moderate and can cause minor to moderate damage near the epicentre.
The energy release is concentrated enough that anyone within a few tens of kilometres would have felt a sharp jolt; further away, the shaking attenuates quickly. This was not a major tectonic event, but it is a reminder of the seismic activity in southern Mexico.
The USGS records show that at least 394 earthquakes of magnitude 5.0 or greater have occurred within about 300 kilometres of this location over the past two decades. The strongest on that list was a magnitude 8.2 event in 2017. Today’s event is a far smaller cousin, but it shares the same tectonic driver: the subduction of the Cocos Plate beneath the North American Plate along the Middle America Trench.
Aftershocks and Preparedness
Seismologists note that aftershocks are common following an earthquake of this size. They may continue for days or weeks, and people in the affected area are generally advised to be prepared for further shaking. The probability of a larger event is low — the stress released by a magnitude 5.1 is modest — but the regional seismic background means further settling of the crust is routine.
The USGS’s detection and rapid cataloguing of the event relied on its global network of seismometers. As ever, the detail that matters: a moderate, shallow offshore quake in a seismically active region.
Not a headline-maker in its own right, but one that underscores the persistent tectonic restlessness along Mexico’s Pacific coast. The six people who reported feeling it are perhaps the most useful data point — a reminder that even a 5.1 can be felt, even if only briefly, and that the ground under our feet never stays still for long.
