Mexican scientists leave for Brecha de Guerrero to measure seismic activity

Borja Ilian Mazatlán (Mexico), 25 Mar A team of nine scientists studying the dreaded Guerrero Gap will set sail this Saturday on the oceanographic vessel El Puma to that maritime seismic area to find out how high the risk of a major earthquake. The nine scientists and the support team, which includes a reporter from the news agency Efe, passed tests for covid-19 isolated for a few days in a hotel in Mazatlan (western Sinaloa state) to ensure that none of the travelers on board the ship are infected. The expedition includes eight scientists from the National Autonomous University of Mexico (UNAM) and one from the University of Kyoto, led by seismologists Victor Manuel Cruz Atienza and Yoshihiro Ito. The fundamental objective of the team of scientists is to collect the seismographs that have measured the activity of the Guerrero Breach and that should have been rescued in 2020, but the outbreak of the covid-19 pandemic made it impossible to organize the expedition before. The current seismic activity of the Guerrero Breach and the more than 120 years that have passed without a major earthquake in this area of 160 kilometers in length keep specialists on alert. The project of the Mexican-Japanese team of scientists began six years ago to study the intense activity in the Guerrero Breach. In the last week there have been two earthquakes of magnitude 4.8 and 4 on the Richter scale — on March 18 and 22 — with an epicenter in the Guerrero Breach, which gives an idea of the ongoing seismic activity in the area. The scientists took advantage of their stay in the port of Mazatlán to study the latest telluric movements and find out the possibilities of high magnitude earthquakes such as the last category 7 that occurred on September 7, 2021 in the Guerrero Breach. SLOW EARTHQUAKES A similar phenomenon happened in 1962. The measures collected indicate that an earthquake equal to or of greater magnitude than last September can happen, even if it is not something categorical, explained to Efe Victor Manuel Cruz Atienza, geophysicist at the National Autonomous University of Mexico (UNAM). The doctor in seismology Sara Franco, a member of the expedition, adds that since 1997 when the Cayaco station was installed in Guerrero, with which the deformation of the earth's crust associated with tremors is continuously observed and analyzed, the existence of so-called slow earthquakes has been recorded. “This type of earthquake causes a transmission of the accumulated energy towards the limits of the Breach,” which would explain why it is in the periphery that mega-earthquakes occur and not in the very center of the Breach, he added. There is a consensus among the scientists of the expedition that since last December the Guerrero Breach has been influenced by the action of a slow earthquake. Analyzing the consequences of this phenomenon is one of the research objectives of the expedition, that is to find out whether this involves the release of energy or the prolegomenon of a major earthquake. The analysis of data from seismometers installed in November 2019, the last time this group of scientists sailed together into the waters of the Mexican state of Guerrero, is crucial in trying to understand which of the two possibilities is the most plausible. The expedition plans to set sail on Saturday from the port of Mazatlán (Sinaloa) to sail 1,400 nautical miles to the marine area heading for the Guerrero Breach, in search of the seven seismometers that will serve to ascertain the seismic activity in this area that connects the Cocos and North America plates. CHIEF bi/esc/lll (photo)