In this blog post, we will explore the plate boundaries around Costa Rica, and the volcanism that is formed from these boundaries. We will also discuss the mechanisms of one of Costa Rica’s most recognized volcanos.
Both of these images below show the Cocos oceanic plate subducting under the Caribbean continental plate. Due to this subduction, the northern part of Costa Rica will experience active volcanoes.
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| Plate Tectonic Movement Visualizations, Compiled by Jeff Crabaugh and John McDaris (SERC). |
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| Map by Geology.com and MapResources
Red lines are plate boundaries, responsible for volcanism. Arrows show generalized directions of plate movement.
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There are over 200 volcanic formations in Costa Rica among three volcanic ranges. They are the Guanacaste, Central Volcanic Range and the Talamanca. This map shows the location of the most recognized peaks, including the famous Arenal Volcano in northcentral Costa Rica (in the Guanacaste Range).
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| Line A-B marks the location of the plate tectonics cross-section shown below.Map by Geology.com and MapResources. |
Arenal Volcano:
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Image © iStockphoto / M. Gabrenya.
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Arenal Volcano is a conical stratovolcano (tall and symetrical, formed by “layers” of past eruptions) that stands on the shore of Lake Arenal in northcentral Costa Rica. This volcano is formed by a convergent boundary, as the oceanic crust subducts underneath the continental crust, melting rock into magma.
It is the youngest and most active volcano in the country, and has been in near-constant eruption for 7,000 years. This volcano is very explosive when it erupts, as composite volcanos are a mix of felsic and mafic rock composition. This means the flow of lava will consist of andesite, which is moderately viscous and known for large eruptions. In the eruption of 1968, 3 surrounding villages were burried and 87 people died. This eruption consisted of a pyroclastic flow (fast and dangerous ground-hugging flow of ash and rocks) and spewed out a huge ash cloud. Ash is composed of tiny rocks called Tephra which are especially dangerous to be around; when inhaled, it is harmful to human health. Sometimes ash clouds like the one from 1986 (pictured below) can blow deposits hundreds of miles away from the site of the volcano.
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