Written by By Staff Writer
Sky and clouds in the western United States may be catching up with those in the eastern United States.
A Delta-19 eruption at Coahuila Volcano in Mexico has been detected by two near-field seismic stations to the east of the volcano, which indicates that a change in weather has reached the region, according to Eduardo Perez, a glaciologist at the Los Alamos National Laboratory in New Mexico.
“What we’re getting from near-field seismographs on the ground, in fact, is a feedback loop between ground motion and air movement that started very close to the volcano itself,” Perez said during a discussion with colleagues at the Bulletin of the Seismological Society of America.
The near-field seismographs detect signals from earthquakes down to less than 10 miles below the surface. By collecting and analyzing the signals, the scientists are able to create better models of volcanic activity and even better maps of geologic structures.
In addition to the seismic stations that indicate Coahuila Volcano’s change of weather, two other near-field instruments have observed indications of an explosion within the area, according to Leila Sauve, a professor of geophysics at the University of Miami.
In a follow-up analysis of the unusual conditions in the area, Sauve pointed out that the technical name for the eruption model used by the co-authors was “Delta-19,” which is what is called a delta plus variant.
Like variation in the Earth’s axial tilt, Delta-19 variants are unique to an individual volcano. Some can be symmetrical, while others can be split into tiny bents.
Delta-19 occurs when two points of the Earth’s crust are mashed together and that rubble piles up to form an island.
“I think this is unique,” Sauve said of the situation in the western United States.
Because of their history with Delta-19, scientists have developed models that can predict the environment within the crater area at Coahuila. Those models predict a hotbed of earthquakes, explosions and cloud formations, Perez said.
Therefore, when a repeat eruption occurs at Coahuila Volcano, it would be expected to emit more cloud formations, partially because the amount of energy in the eruption would be greater, Perez added.
Earthquakes also increase during an eruption, Perez said. The kind of earthquake usually observed in a Delta-19 is a shallow subduction zone earthquake, a type of quake that comes from the centre of the Earth’s tectonic plates colliding and making a new fault line.
Calculating the amount of radiation emitted in an eruption, especially if it is one involving a Delta-19 variant, can take a number of months, Perez said.
Sauve said, however, that the models could help predict when Delta-19 variants occur.
Related: Scientists lead efforts to map eruption zone