Costa Rica’s current earthquake disaster is only one of many seismic events that have affected the country in its recent past. One of the most dramatic of these events was the eruption of the Irazú volcano in 1963.

Many people still remember Irazú’s eruption, because of its profound effect on San José and the whole Central Valley. One visitor describes the eruption this way:

I remember “… the ‘black snow.’ This is not figuratively speaking. I mean literally. Irazú had acted up and was spewing out ash. One would brush ash from a car as if they were up north facing a snow storm. I don’t remember how long it ‘snowed.’” We arrived in Costa Rica sometime in the middle of November 1963. When that ‘snow’ stopped is when I fell in love with Costa Rica and her people.”

For those unfamiliar with volcanoes and their eruptions, Irazú was particularly disturbing. People would walk to and from work through a shower of fine, black ash, and at the end of the day, their clothing was stained black. When it rained, the water would mix with the ash in the air, creating a thick, soot-colored rain. Buildings slowly darkened, and the sun was constantly masked by the eerie black fall of ash. To visitors who arrived in Costa Rica during the eruption, the whole country seemed bleak and grimy. And when the eruption finally ended in 1965, many people, like the above visitor, saw Costa Rica’s true beauty for the first time.

In the past few days, vulcanologists have been monitoring some sporadic activity at the Poás volcano, which was very close to the epicenter of the January 8th earthquake. Just after the earthquake, the volcano began to rumble and show signs of some activity. However, scientists from the Costa Rican Vulcanological and Seismological Observatory (Observatorio Vulcanológico y Sismológico de Costa Rica—Ovsicori) denied that the volcano’s activity was in any way caused by the earthquake. Instead, they determined that the volcano was merely making periodic shifts and adjustments, of a type it constantly seems to make. Scientists recorded similar volcanic activity at Poás in January 2008.

As routine as it supposedly is, some of the recent activity at Poás has been spectacular. On Monday, January 12 and Wednesday, January 14, the volcano had two phreatic eruptions—releases of steam, rock, ash and water. This type of eruption apparently occurs when very hot magma rises from beneath the earth’s surface and touches ground water, creating a sort of steam explosion. Phreatic eruptions do not involve lava, although they can release noxious or poisonous gases. Monday’s activity began with the appearance of what an Ovsicori spokesperson called a large “bubble of liquid” at the center of the volcano’s crater lake. Soon afterward, a stream of ash, vapors and rock shot about 50 feet into the air.

Phreatic eruptions are fairly common at the Poás volcano, making it a prime tourist attraction. Spouts of steam frequently shoot out from the volcano’s two crater lakes. Visitors can get very close to—and actually peer into—these crater lakes. They can also examine the volcano’s sulfur lakes, said to be unique in the world.

At this time, the Poás volcano national park (Parque Nacional Volcán Poás) is closed, so that emergency vehicles can more easily reach the earthquake-ravaged areas at its base. However, most tourist attractions are still open, as are Costa Rica’s other volcanic national parks.

Resting as it does on a constantly shifting geological base, Costa Rica boasts an ever-changing natural beauty.

Click here to read about recent eruptions at the Poás Volcano.

Click here to learn more about phreatic eruptions.

Writing and editing by Beaumont Hardy Editing.

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