A team of about 50 experts is carrying out studies in Michoacán to determine whether increased seismic activity could be a precursor to the birth of a new volcano.
There have been more than 2,000 earthquakes with magnitudes between 2.9 and 4.1 in an area northwest of Uruapan, Michoacán, since January 5, according to the National Seismological Service (SSN).
The earthquake swarm, as a sequence of similar magnitude seismic events occurring in a local area in a relatively short period of time is known, could be related to either tectonic or magmatic events, the director of the Institute of Geophysics at the National Autonomous University (UNAM) told the newspaper El Financiero.
A magmatic event, Hugo Delgado explained, occurs when magma – the molten or semi-molten material from which igneous rocks are formed – ascends to the surface of the earth.
Large volumes of magma can potentially break through the surface and form a volcano, as occurred in Michoacán in 1943 with the sudden emergence of the Paricutín Volcano, which eventually rose to a height of more than 300 meters.
However, there is no certainty that that will happen near Uruapan, Delgado said. Even if the earthquake swarm is related to a magmatic event, “we still have to see if there is sufficient magma for it to rise” from beneath the Earth’s surface, he said.
The expert also said that while seismic activity that preceded the birth of the Paricutín Volcano was felt by local people, the recent earth tremors were not.
Recent history suggests that the formation of a new volcano is unlikely.
The UNAM volcanologist said that earthquake swarms also occurred in the same area of Michoacán in 1997, 1999 and 2006 but they were related to tectonic rather than magmatic activity.
“While it’s not common, it’s not rare for these kinds of phenomena [earthquake swarms] to occur. The previous events were related to fault lines and fractures in the [earth’s] crust below Michoacán,” Delgado said.
Still, the location of the seismic activity near both the Paricutín and Tancítaro volcanos has attracted the attention of experts from several universities as well as government agencies including the SSN and the National Disaster Prevention Center (Cenapred).
Cenapred said that the experts on site in the area where the seismic activity has occurred have installed seismometers and other measuring equipment, and are analyzing water and gas samples collected there. They are also closely monitoring the surface of the earth for any signs of deformation.
Delgado said that while meteorologists have the capacity to forecast rain, for example, because they can look at cloud formations using both satellites in space and instruments on earth, seismologists and volcanologists cannot accurately predict when or where an earthquake might occur or a volcano may form.
“… unfortunately we can only see [what’s happening beneath the earth’s surface] using equipment at the surface” and not from beneath the crust, he said.
“That’s why follow-up and monitoring near the phenomenon is very important in order to be able to understand, as far as is possible, what is happening. . .”