San José, Costa Rica, since 1956

Costa Rica's volcanos experience a busy 2010

Four of Costa Rica’s five active volcanoes registered significant activity this year, recording everything from lava and ash eruptions to evaporated crater lakes.

According to a communiqué from Costa Rica’s Volcanological and Seismological Observatory (Ovsicori) based at the National University, 2010 was “one of the rare cases in which activity was reported in four volcanoes simultaneously.”

An active year began in early 2010 when in January the Turrialba Volcano on the Caribbean slope surprised residents with eruptions of ash and rock, opening new crevices in the volcano’s crater and emitting a glowing red and orange steam, indicating that lava had begun to bubble in the depths of the volcano. Scientists measured temperatures at the crater between 160 and 600 degrees Celsius.

Gases from the volcano caused acid rains in Turrialba and scorched trees and plants on the slope of the mountain, turning the foliage from green to white and gray for up to 10 kilometers from the volcano. To date, the vegetation remains hoary.

Arenal Volcano in north-central Costa Rica maintained a “moderate spew of short lava tails and sporadic eruptions,” activity that provoked landslides, the Ovsicori reported. In May, the volcano produced several fiery flows, awing onlookers and forcing a temporary closure of the national park. The easternmost cone near the peak of Arenal reopened this year and began hurling “incandescent material” toward the north and east.

At Poás, an active volcano towering over the Central Valley, northwest of San José, an eruption on Dec. 25, 2009 forced dozens landslides throughout the opening weeks of 2010. Temperatures between 34 and 58 degrees Celsius forced lake evaporations at the crater of Poás that emitted turquoise and gray steam.

Due to high temperatures, the lake inside the crater at Irazú, a volcano towering over Cartago to the east of San José, dried up in May for the first time in two decades. The lake did not start to refill until the heavy rains brought on by Hurricane Thomas drenched Costa Rica at the end of the year.

The Ovsicori maintains permanent monitoring stations at all of Costa Rica’s active volcanoes and performs routine visits to the rumbling wonders. For monthly updates on the state of Costa Rica’s volcanoes, visit: (only in Spanish).

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