A magnitude 7.4 (7.4m) Earthquake recently occurred at 15:29 UTC

12 km SSW of Santa María Zapotitlán, Mexico

The earthquake sent waves throughout southern Mexico and was felt a few hundred miles from the epicenter. The epicenter occurred near the urban area of Oaxaca, where some more significant damage has been reported. Communications with Oaxaca are limited at present due to damaged infrastructure. The earthquake is a result of reverse / thrust faulting due to subduction of the Pacific plate under American plate material.

Image above: ground shaking intensity map (Credit: US Geological Survey), showing low levels of shaking (capable of being detected by people) spreading throughout central Mexico. The area is very tectonically active with several very severe (greater than M7.0) earthquakes having occurred in the past 100 years. For example, on 9th October 1995, a M 8.0 earthquake struck the Colima-Jalisco region, resulting in 49 fatalities. Similarly on 19 September 1985, a shallower 8.0M earthquake struck a more populated area resulting in near 9,500 fatalities. Shallower earthquakes are more severe as less “seismic attenuation” (i.e., weakening of seismic waves during vertical ascent) occurs. Additionally, although it’s unlikely that this event will be as severe in it’s impact as the earthquakes described, there could still be some pretty severe damage in the areas near the epicentre. As the magnitude scale is logarithmic, a M 7.4 event is roughly 5 times weaker than a M8.0 event.

It is yet unconfirmed just how severe the damage is in the worst affected areas, however reports should arrive in the coming hours.