Geologist explains complex work in monitoring volcanic activities

A Filipino geologist explained that scientists conduct meticulous study of volcanic activities and the effects to nearby communities to be able to keep people safe.

Dr. Carlo Arcilla, a geologist and the Director of the Philippine Nuclear Research Institute (PNRI), said the process is difficult.

Unlike typhoons which could be monitored using satellites, there was no way to capture volcanic activity as it happened in real-time below the Earth's surface, he explained.

He made the statement after Presidential spokesman Secretary Salvador Panelo said President Rodrigo Duterte is satisfied with the work turned in by scientists who monitor the activities of Taal Volcano, which has become restless since its phreatic eruption last Sunday, Jan. 12, 2020.

Arcilla explained that phreatic or steam-driven eruptions were more difficult to forecast, compared to other volcanic activities.

"Phreatic eruptions are difficult to predict if you don't know when [the water in Taal Lake] will be boiling. So it could be very, very sudden. Parang walang signal iyan," he said in an exclusive interview with GMA News Online.

Arcilla said it is easier to forecast magmatic, magmato-phreatic and other types of eruptions.

He added that there are three ways that scientists use in predicting when a volcanic eruption might occur. He, however, noted that geologists must use all of these together when forecasting an eruption.

Presence of volcanic earthquakes

"So bago iyon mag-e-erupt... magma starts moving upward [towards the Earth's surface]. When the magma gets in contact with the rocks, the movement creates small earthquakes," Arcilla explained.

These small earthquakes are volcanic in nature.

The former director of the UP National Institute of Geological Sciences (UP NIGS) also dispelled the misconception that the earthquakes caused volcano activity. He said it was the other way around.

Geologists are able to measure volcanic earthquakes by using seismometers or devices that measure quakes.

Presence of volcanic gases

The three dissolved gases in magma are sulfur dioxide, carbon dioxide and water vapor, said Arcilla.

Scientists often use specialized instruments to measure dissolved gas in the air.

The PHIVOLCS uses a FLYSPEC spectrometer which measures sulfur dioxide.

"If the sulfur dioxide content increases, it means that the volcanic eruption could be imminent or the magma is moving towards the surface. If there's sulfur dioxide, the magma is relatively at shallow pressures, at malapit na siya sa surface," the geologist explained.

Recently, one of the PHIVOLCS spectrometers stopped working because it got covered in ash.

Bumps in the sides of the volcano

Arcilla said the movement of magma to the Earth's surface will cause volume expansion in the sides of the volcano. They are manifested by bumps on the volcano's flanks.

According to him, this can be detected by accurate surveying equipment.

Since Sunday, Taal Volcano has experienced a number of phreatic and magmatic eruptions. As of Friday, the volcano remains under Alert Level 4, which means that a hazardous eruption is possible within hours to days. — BAP, GMA News