Magma Zone Beneath Volcanoes Causes Powerful Eruption

Siesmologists have found the causes behind the 1912 Novarupta eruption on the Alaskan Peninsula.

A team of seismologists installed a network of seismometers around the Katmai Volcanoes on the Peninsula to identify what caused the Novarupta eruption that spewed massive amounts of ash and magma.

Based on the data collected during the span of four years, the team has found that the magma plumbing system below the group of Katmai volcanoes caused the Novarupta eruption. The katmai volcanoes are located about 6 miles (10 km) from Novarupta, which spewed ash and magma into the air for about three cubic miles and it fell an area of 3,000 square miles, according to OurAmazingPlanet.

The Katmai volcanoes are located in the subduction zones, where one tectonic plate moves below another plate at the convergent boundaries. These zones are noted for higher rates of volcanic eruptions.

As the Novarupta volcano erupted in 1912, Mount Katmai which is just 6 miles away gave way, which the scientists believe was because of the presence of magma beneath Mount Katmai. The Novarupta eruption was the largest and most powerful volcanic eruption of the 20th century, which even drained the magma present below Mount Katmai.

"There probably was a large volume of magma beneath the Katmai area, and as it sat there and cooled a bit, it lost its ability to hold volatiles and gave off gases," Clifford Thurber, a seismologist at the University of Wisconsin-Madison who led the study, told OurAmazingPlanet. "Basically the whole region was stressed by this pressure-cooker magmatic system, and those stresses could cause earthquakes."

The researchers used two methods - body wave tomography and ambient noise tomography- and using seismic waves and computer processing, they found that two magma reservoirs are located in the Katmai area. 

While one magma reservoir located below Mount Katmai, the other one is located beneath the Mount Mageik, which is also 6 miles away from Novarupta but in a different direction.

The researchers point out that the quantity of magma present is enough to cause volcanic eruptions but not as powerful as Novarupta.