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On September 25, 2019, the American Geophysical Union (AGU) website released a message saying that new research found that the seemingly low-risk earthquake zone in Mexico has experienced many strong earthquakes since 1,500, which shows that there are many active faults in the area that have not been mapped yet. These areas are located in the volcanic belt of across Mexico, and are inhabited by about 40% of the Mexican population, but they may not know the country's earthquake history.
New research led by scientists at the National Autonomous University of Mexico collects archives that record historical earthquakes in the volcanic belt and converts historical reports into numerical data. This new study published in in Tectonics points to at least 16 major earthquakes in the past 450 years, challenging existing understanding of seismic activity in this area.
TransMexico Volcanic Belt is a 1000 km (621 miles) long volcanic tectonic activity area that spans the central and southern parts of Mexico, and extends to the Pacific Ocean. It is home to many city centers, including Mexico City . Earthquake danger is the probability of an earthquake occurring in a certain area within a specific time range. scientists believe that the risk of seismic transMexico volcanic belt is low due to few earthquakes recorded.
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Researchers collected historical records from the Mexican Archives and used these records to classify individual earthquakes from 1568 to 1920. They selected 16 earthquakes, which had sufficiently detailed records, including locations, damages, etc. For example, a magnitude 7.6 earthquake occurred in Michoacan in 1858, with the epicenter in the city of Morelia in the center of the volcanic belt. Documents since then have proved the devastating consequences of the earthquake to the state.
The researchers used the Modified Mercalli Intensity Scale to convert evidence in the archives into numerical values, which ranks earthquakes based on the intensity of damage or the feelings of the crowd. A "severe" earthquake could move furniture, and a "violent" earthquake could cause buildings to collapse. The scale helps scientists assign intensity data to each earthquake and then use numerical methods to estimate the magnitude and epicenter.
results show that earthquakes occurred throughout the transMexico volcanic belt, even in areas with inactive geology. These earthquakes are particularly common in the central and western volcanic belts. Further research by shows that some of these are related to blind faults or faults that are not visible on the Earth's surface. Even in areas where it has not been able to explore active tectonic faults, earthquakes may occur, the researchers say.
Please indicate the source and author of this article: Lanzhou Literature Information Center, Chinese Academy of Sciences "Dynamic Monitoring Express of Earth Sciences" No. 20, 2019, compiled by Zhao Jidong.
