Saturday, March 08, 2008

New volcano discovered in San Carlos, Costa Rica

By Alejandra Vargas / La Nacion
Translated by Uri Ridelman

Amidst the virgin jungle of San Carlos, there's a volcano with a crater similar to the one the Irazu volcano has and eight times bigger than the crater of the active Turrialba volcano. This volcano had been hiding under the dense clouds of an inaccessible site.

This was confirmed yesterday to La Nacion newspaper by Wilfredo Rojas of the National Seismologic Network.

This colossus, known also as the Cerro El Porvenir (El Porvenir Hill), is an inactive volcano of conic shape. It's located in the limit between San Carlos and Alfaro Ruiz, in the heart of the Juan Castro Blanco National Park in San Carlos. The volcano's location is very remote, rarely visited and hardly known at all by the locals.

This volcano has an altitude of 2300 meters (7546 feet) and its crater has a 200-meter (656-feet) diameter and a depth of about 60 meters (197 feet). Inside the crater there is lagoon with an area of about 7000 square meters (22966 square feet).

How did they find it?

Historically there was no record that this volcanic crater existed in that place, nor reports from locals that suggested any type of activity.

That's why last Thursday scientists had to walk to the aforementioned place, for about eight hours, to corroborate its existence.

Everything started about a year and a half ago, when experts observed the infrared images taken by the WB-57 NASA airplane in 2005. This was part of a mission that photographed all of Costa Rica from the air in order to get to know better the geography of Costa Rica.

"Studying the two geological faults active in the zone we realized that there was some sort of crater right underneath the peak of El Porvenir," Rojas said. That's why we wanted to pay a visit on foot to corroborate our suspicions."

Since the scientists knew the coordinates (497.158° latitude and 250.592° longitude) of the crater thanks to the NASA images they used local guides along with GPS devices to search inside the national park and reach the volcano's crater.

"We did the tour on Thursday because during this time of year the crater's site has the best weather conditions and visibility," Rojas said. This is traditionally a very cloudy site."

The walk started in San Jose de la Montana (San Jose of the Mountain) and the prize after a dangerous descent off a 200-meter cliff was finding the crater and the lagoon.

"We can't tell right now whether or not there's a risk of volcanic activity," Rojas said. "However, scientifically speaking, as of now we only know that it hasn't had any activity in a long time."

Rojas said that the next step will be to determine the age and extension of the dry lava found on the site. This analysis will be made using carbon-14 dating tests to study the rests of organic matter on the rocks.

The inside of the crater will also be analyzed in order to study the viscous magma and the geochemistry of the crater's lake.

"It's really amazing to find a volcano's crater in the 21st century," Rojas said. "This is just getting started"

Between faults

This is the last volcano of the Central Volcanic Mountain Range and it's located between two very active geological faults, the Congo Fault (on the left) and the El Porvenir fault (on the right). A geological fault is a fracture or crack in the earth's crust.

Rojas pointed out that El Porvenir is classified as a stratovolcano, which means that it has several layers of hardened lava showing its activities and age.

"Even though vegetation around it suggests that the volcano has been inactive for hundreds of years, we are sure this is in fact a volcano because of the crater and because around it there is evidence of lava eruptions, rock explosions and gases of considerable magnitude," Rojas said.

Based on the rock type and sediments discovered these eruptions could date back to the Holocene Epoch, which happened 11 thousand years ago and coincides with the end of the glacial times.

The volcano is about two million years old -about the same age as the other volcanoes in this mountain range- and was formed due to the subduction of the Cocos plate beneath Costa Rican territory.

Note: this article is property of La Nacion. It was translated almost word-by-word, voluntarily and at no cost, by me. I am not an employee of La Nacion nor associated to them in any way. If you want to read more on this important discovery or look at the original article (in Spanish) along with the infrared NASA picture and other graphics you can click here.


dan_deneau said...

"Since the scientists knew the coordinates (497.158° latitude and 250.592° longitude)"

Those coordinates don't make any sense. A latitude coordinate can only be -90 to 90, and a longitude can be -180 to 180.

Uri R. said...

Thanks for the heads up I will try to verify that...

Uri R. said...

Strangely enough this were the correct coordinates according to the newspaper. Could these be GPS coordinates and thus be different from regular coordinates? Does Anyone know about this?

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