Guerrero Breach: Scientists Detected the First Slow Earthquake in Mexico's History

Scientists hope to confirm with the data collected on the ocean floor that in the first months of this year there is a slow earthquake under the sea off the coast of Guerrero, a phenomenon that had not been recorded in the history of Mexico.

The Mexican-Japanese expedition of the National Autonomous University of Mexico (UNAM) and the University of Kyoto concluded its mission on Wednesday by docking the ship El Puma in the port of Mazatlan, Sinaloa.

The head of the Mexican team, Dr. Víctor Manuel Cruz Atienza of UNAM, has explained that the slow earthquake that seems to be occurring could cause, if there is an earthquake similar to that of last September in the coming weeks, a larger earthquake.

Seismic activity in Guerrero's Costa Chica reported by the National Seismological Service is currently “anomalously high,” Cruz Atienza said, probably due to the slow earthquakes that occurred from September to the present day.

This entire seismic panorama has similarities to the events prior to the magnitude 9 earthquake in Japan that caused 15,000 deaths in 2011, along with a large tsunami, “which does not mean that the same thing will happen”, clarifies Cruz Atienza.

The high number of tremors produced on the coast of Guerrero in the last five years serves to alleviate the energy accumulated by the coupling of the continental plates of Cocos and North America.

After 13 days at sea and traveling more than 2,500 nautical miles, about 4,500 kilometers, El Puma completed its mission which, among other tasks, was to collect seven seismographs installed on the seabed of the Guerrero Breach to study the seismic activity in the area.

The Mexican-Japanese project, with a budget of six million dollars and six years of work interrupted by the Covid 19 pandemic, will continue with the study of all the data collected by the expedition.

The mission succeeded in rescuing three of the seven seismometers installed on the seabed in 2019 and was able to place another eight seismometers to provide valuable data in the coming months.

Although partly frustrated by not collecting four seismometers, the expedition is pleased with the valuable data collected on seabed pressure that will allow observing the vertical deformation of the continent and the acoustic GPS data obtained by wave gliders.

“We have never observed the slow earthquakes under the sea directly in Mexico,” said Dr. Víctor Manuel Cruz Atienza.

“These silent slides between the plates, collected by the scientific expedition, are those before and after the earthquake in Acapulco in September 2021,” he added.

Also for the first time in Mexico, the deformation of the ocean floor caused by an earthquake has been recorded, adds the doctor from UNAM.

Yosihiro Ito, chief scientist of the Japanese part of the project, was also pleased with what was achieved.

“I need to compare the data collected at sea with those on land, but the most important thing is that with the pressure data from 2017 to 2022, we will be able to know where is the greatest friction zone in which the great earthquake could happen,” he said.