Costa Rica is a seismic very active country and is said to have way over 100 volcanoes. Central America forms a small bridge between North and South and America. Costa Rica forms a relatively small strip of land, where impressive mountain ranges form its backbone. All along this backbone of mountains volcanoes are present. From the Rincon the la Veija and Arenal Volcanoes in the north, the Barva and Poas Volcano in the northern part of the Central Valley, to the Irazu and Turrialba volcanoes in the South. The presence of so many volcanoes in Costa Rica is explained by a geological phenomena; the movement of tectonic plates. The mountain range of Costa Rica is placed over a ridge where two tectonic plates meet. The Cocos plate moves slowly to the east at a speed of approximately three inches per year and is pushed under the Caribbean plate. These two plates are part of a global system of twenty-five tectonic plates, which are constantly in motion. The plates are floating on the melted layer in the earth core called aesthenosphere. When 2 plates move together, the edges are pushed down and melt. The magma that is formed is pushed up and forms a ridge of volcanoes. The strain on the Cocos plate has been so big, that is has broken into seven different pieces rubbing against the Caribbean plate. The friction it creates is released in the more than 3,000 earthquakes that occur in Costa Rica every year. Most of these quakes are so soft that they cannot be felt. Only a dozen can, but since Costa Rica has a long history of receiving these blows of Mother Nature, there are few high-rise buildings. Modern engineering is incorporated to make new buildings seismic proof. In the past erupting volcanoes and earthquakes have done their share of destruction. Proof can be found in the form of the ruins of the church of Cartago, close to the Irazu volcano. The famous iron church of Grecia was constructed to defy the forces of nature and still stands. In 1991 a fierce 8,4 earthquake hit the Atlantic part of Costa Rica. This earthquake was not only extremely destructive by destroying more than 3,000 building, but also lifted some parts of the Province of Limon up to five feet, destroying most of the coral reefs in front of the shores. To experience the seismic activity first hand, you should visit one of Costa Rica’s seven active volcanoes. The crater of the Poas Volcano offers a view of steaming hot bubbling magma and a nose full of sulfur vapors. The Irazu Volcano has a beautiful emerald colored crater lake, where changes in chemical composition offer spectacular color shifts. But the most magnificent show is provided by the Arenal Volcano, with its spectacular eruptions, lava streaming off the sides and surrounding hot springs.