By Wendy Anders

Cartago province’s Turrialba Volcano, which neighbors the densely populated San José, Costa Rica metropolitan area, had four intense eruptions yesterday, Monday, September 19, emitting abundant clouds of ash and spewing incandescent rocks. The eruption continued throughout the night and during all of today, causing two San José airports to be closed.

Data on the volcano is compiled and reported on at least twice daily during the volcano’s active phases on the National University’s Volcanology and Seismology Research Institute’s (Ovsicori-UNA) Facebook page. The institute also uses reader comments and observations to add to their computer-generated models and maps of ash fall and other effects of the volcano.

It all began at 2:53 Monday morning with a 15-minute eruption that sent up a column of ash 1,000 ms above the volcano’s peak. And at 11:32 a.m. a larger blast sent up a 4 km column. Two other eruptions yesterday took place at 2:37 p.m. and at 3:20 p.m., noted Ovsicori.

Yesterday’s mid-afternoon eruption continued all night and ceased at 4:03 p.m. today, for 25 hours of sustained volcanic activity. Today’s sustained activity consisted of intermittent emissions of ash, gas, and steam of heights ranging from 200 – 400 ms above the crater, said Ovsicori, a marked decrease from Monday’s intense blasts.

A shift in winds on Tuesday coupled with scattered rains in the region have diminished ash in the air, so Wednesday morning will likely not be an unexpected ash-Wednesday after all.

According to Ovsicori, yesterday’s eruptions created a high concentration of particles in the atmosphere. The concentration of solid particles with a diameter equal or less to 10 micrometers (in this case ash particles) was double that measured after the volcano’s last large eruption on July 25 when a 1,300 km column of ash was blasted out. Yesterday afternoon and evening, these particles were found to be at between 25 and 460 parts per cubic meter, whereas under normal atmospheric conditions the concentration would be at 10.

Despite many reports of sulfur odors, the concentration of sulfur yesterday was not greater than previous eruptions, said Ovsicori.

And if that sulfur smell is getting to you, there may be a silver lining. According to the Boulder, Colorado-based National Center for Atmospheric Research, Costa Rica’s Turrialba volcano may be helping to slow down global warming:

“Often, erupting volcanoes emit sulfur dioxide into the atmosphere. Sulfur dioxide is much more effective than ash particles at cooling the climate. The sulfur dioxide moves into the stratosphere and combines with water to form sulfuric acid aerosols. The sulfuric acid makes a haze of tiny droplets in the stratosphere that reflects incoming solar radiation, causing cooling of the Earth’s surface. The aerosols can stay in the stratosphere for up to three years, moved around by winds and causing significant cooling worldwide.”

After this second airport closure of 2016 due to volcanic ash, Vivian Chacón an aeronautics lawyer spoke to the press to say that in addition to the security measures and alternate plans currently in place in the event of natural disasters, the country’s Civil Aviation Directorate is also currently looking into developing a contingency plan together with the Daniel Oduber International Airport in Liberia, capital of the northern Guanacaste province. This would involve the Liberia airport operating 24 hours a day in the event of a closure of the San José airport, said Chacón, a lawyer with the Costa Rican BLP law firm.