The Tropical Paradise of Costa Rica is Currently Facing a Little Problem: Four Active Volcanoes!


The small Central American nation of Costa Rica has a lot going for it: gorgeous weather, some of the most diverse ecosystems on Earth, hundreds of well-preserved beaches, superb health services, warm and friendly people. It has no military, which was abolished in 1949, and a solidly democratic government. No wonder it’s consistently ranked among the safest and happiest places in the world. But wait, don’t pack your bags just yet. Did you know there are currently four – not one, not two, not three, but four! –active volcanoes spewing ash into the Costa Rican skies? The Turrialba, Irazú, Rincón de la Vieja, and Poás volcanoes have been behaving like hulking, passive-aggressive bullies. Their miles-high plumes of debris have forced airlines to cancel thousands of flights to and from there, and covered large portions of the country with ever-present gray dust. They aren’t expected to send forth rivers of lava anytime soon. But then again, who knows? For millions of Costa Ricans (including my parents and many of my close relatives) they have been an annoyance to live with. What are the chances that they will become a real danger to escape from?

When I was a school-kid in San José, Costa Rica, we had to memorize the names of the country’s nine volcanoes. Since then geologists have added six more to the list. That’s fifteen volcanoes in an area smaller than West Virginia! They are all found on the mountain range that bisects Costa Rica diagonally from north-west to south-east, and is part of the great Cordillera that includes the Rocky Mountains in North America and the Andes in South America. When I was a kid, only one volcano was active: the beautiful Arenal, which looks like a cartoon volcano, almost perfectly triangular, with a wide crater at the top. For many decades Arenal wowed locals and tourists with daily lava shows, until its activity came to a sudden stop around 2008. It was about that time that Turrialba started causing trouble.

The Turrialba volcano is almost twice as tall as Arenal but squatter, with a lopsided top that looks like a giant Cookie Monster took a bite out of it. The fertile soil that surrounds it produces some of the world’s best coffee. It had shown signs of activity in the 19th century but then went quiet for over a hundred years until seismologists started sensing changes underground in 1996. Some ten years later the first ash eruptions occurred. Since then, Turrialba has become increasingly active. Incredibly hot jets of steam from its belly have created new craters at the top, while underground earthquakes (which are common even within dormant volcanoes) increased from some twenty a day to twenty an hour! In October of 2014 a giant plume of ash was expelled by Turrialba and was carried to many areas of Costa Rica’s Central Valley. Since then eruptions have occurred in an unpredictable pattern. The main airport has been shut down dozens of times, creating havoc for the travel and tourist industries. On clear days, the flow of ash carried by the air can be seen coursing through the sky like a ghostly yellow river. On particularly bad days cars parked in the street all turn the same gray hue, and people with breathing problems are warned to stay indoors.

From far away the Irazú volcano doesn’t look like a volcano at all. Its main crater is hidden among the surrounding mountains. For many years Irazú National Park has been a popular destination for inhabitants of the Central Valley, who can take a leisurely walk all the way to the top, where viewing observatories have been place overlooking the iridescent blue lagoon nestled within the main crater. Irazú famously blanketed the country with ash in the 1960s, in a legendary eruption that lasted 700 days. Roofs collapsed under the weight of the volcanic dust, and many deaths were reported of respiratory failure. Irazú then went back to sleep, until it unexpectedly awoke in 2015. Although it has not been nearly as active as Turrialba, Costa Ricans of a certain age remember the havoc of the 1960s and shudder.

When my family and I last visited Costa Rica early this year, we were warned that our return flight to the United States might not take off due to unusually intense volcanic activity. “Great”, I thought. “Turrialba is at it again”. But I was soon informed that the miscreant this time was Turrialba’s northern neighbor, Rincón de la Vieja (which means “the old lady’s nook”). We were ultimately able to make our way home, but old Rincón has kept at it since. Not only has the ash disrupted air travel and caused asthmatics like me to wheeze through the day, but the particularly acidic composition of the ash gives rise to concerns about “plinian eruptions”. Pliny the Younger was the Roman writer who recorded the eruption of the Vesuvius volcano, which destroyed the citied of Pompey and Herculaneum in the year 79AD. There is currently no danger that Rincón de la Vieja will cause Vesuvius-levels of destruction, but plinian eruptions do increase the danger of acid rain, which can be harmful to people and devastating to agricultural crops.

As if all this were not enough, the Poás volcano has suddenly decided to join the party. Poás has a gently undulating flat top, on which three large craters rest, unceasingly releasing clouds of smoke. Historically Poás has played an important role in Costa Rican culture, even in pre-Columbian times, when certain native tribes performed sacrifices to appease its fury. Its silhouette has appeared on Costa Rican bills, and the immensely diverse ecosystem around it attracts millions of tourists a year. This last week, though, Poás made news for two great eruptions, which released large rocks and tons of ash into the air. Areas of the Central Valley previously spared the ashes of Turrialba and Irazú are now on alert mode, waiting to see if these new signs of activity presage more dangerous times to come.

Four active volcanoes, all within sight of Costa Rica’s largest cities. According to seismologists, there does not appear to be danger of catastrophic eruptions from any of them in the foreseeable future. In a sense it’s good that they sporadically send their innards into the air, because this reduces the pressure inside and decreases the chances of earth-shattering explosions. But the truth is that it is impossible to know what is going on inside of these titans of nature. It may be that the current flurry of activity is nothing more than a yawn in the midst of their million-year-long lifetimes. Or, it may be that at least one of them is preparing to launch a full-on tantrum, with potentially historic consequences.

For up-to-date information about Costa Rica’s volcanoes, and spectacular images of their eruptions, visit the Costa Rican Vulcanologic and Seismologic Observatory (OVISCORI) – .


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