Virtual Volcano Vacation #142 WINNERS! – Turrialba

Turrialba volcano in Costa Rica – photo by Bernal Saborio [CC BY-SA 2.0] via Flickr

This week’s hunt did not take long at all..and the winner and runner-up found me almost at the same time. I can almost imagine them both in a foot-race under the hot sun way down in Central America in Costa Rica running up the green steep slopes of Turrialba.

Turrialba is a 3340 m high stratovolcano located in central Costa Rica. It sits astride a mountain saddle that extends northeast of the active Irazu volcano. Green forested mountain slopes rise and give way to a less hospitable summit upon which an elongated 800 X 2200 m summit depression has formed.

Turrialba summit depression as viewed from the west – Photo by Federico Chavarria Kopper, 1999.via GVP

The summit depression, breached at the northeast, contains three distinct craters at its higher southwestern corner. Most of the volcano’s activity has centered around these craters, though there are two pyroclastic cones on the southwest flanks.

Though Turrialba has several large explosive eruptions in its earlier history, its more recent activity comes on the heels of a 144 year long nap that began in 1866. An increase in the number of earthquakes and the temperature around fumaroles beginning around 1996 eventually led up to a phreatic eruption at the southwest crater on 8 January 2010. Three more such eruptions occurred in 2011, 2012 and 2013, each increasing in duration and the activity moving from the southwest crater to the west crater.

Turrialba eruption 2014 – phreatic eruption of October 2014 – photo by By Rodtico21 [CC BY-SA 4.0] via Wikimedia Commons

Then, on 29 October 2014, following a month of increased emissions and volcano-tectonic seismicity, Turrialba finally manged to force some magma to the surface. This manifested itself around midnight in the form of a large explosion which obliterated the wall between the central and west craters, partially buried the central crater in ash, and launched an ash cloud 5.8 km into the air. Ash from this explosion was deposited as far as 40 km northwest of the volcano in the cities of San Jose and Heredia. More explosions occurred during the next month. This eruptive phase concluded with a ten-minute spree of strombolian activity that launched ballistics weighing around 5 lbs 300 km from the source and scattering ash as far as 80 km from the source.

Turrialba west & central craters in 2009 – photo by Robert Nunn ]CC BY-NC 2.0] via Flickr

Following another brief nap, Turrialba awakened again in March of 2015 and embarked on an ongoing string of explosive eruptions that have generated increasing amounts of ashfall across the adjacent valley. In June of 2017, a drone reconnaissance of the summit area revealed a 15 X 25 m lava lake within the active crater.

The Turrialba Volcano National Park, established in 1955, encompasses the volcano within its 16 km². At one time park visitors could hike all the way to the summit and descend down to the central crater area. It is also said that on a clear day, one could climb to the summit and be able to view both the Pacific Ocean and Caribbean Sea. However, for the obvious reason, the park is currently closed to visitors…except for virtual-visitors, of course.

This excellent video made in March of 2018 includes drone footage, timelapse video and even some IR video of Turrialba in action.

There are two webcams operated by the Observatorio Vulcanológico y Sismológico de Costa Rica (OVSICORI)…one camera located on Turrialba’s summit depression rim pointed WSW toward the active craters, and the other  9 km to the southwest on Irazu focusing on ash column height above Turrialba’s summit.

OVISCORI webcam monitors Turrialba’s active craters

Congratulations to Kylie who found me first here, and to Leslie who found me just moments later on Facebook. I’m glad to see you both on the scoreboard again. Next week I may give hidden-guesses one more try..we shall see. Thank you everybody who played or followed along…and next Wednesday..same Volcanohead-time..same Volcanohead-channel…find out which volcano I will drop in on next.

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