Riding horses around Lake Arenal - and a picnic
Arenal, as seen from our balloon
Arenal volcano, as seen from Centaura Farm
Arenal erupting - seen from where we ride near the base
Arenal - we just heard the boom from the cone
ARENAL VOLCANO COSTA RICA
One of the most awesome of Centaura's private riding locations is the 1,100 acre cattle ranch at the base of Costa Rica's largest tourist attraction, Arenal Volcano (and surrounding hot springs in Tabacón and elsewhere).
One of the days you'll spend in San Carlos will be on this ranch, with huge pastures, free-range cattle, and a vista over the Arenal Gorge as well as the Arenal Volcano ever present at your backside.
Arenal Volcano is unique in the world. Eruptions are continuous, with big, noisy explosive emissions occurring every few hours. This generally relieves whatever interior pressure has built up and releases gases. During the day you can see the peak and slopes emitting visible steam. Only at night are the glowing lava flows visible. However, the peak is now so high that it is often shrouded in clouds, so lava visibility often is not possible.
The volcanic explosions create a very high speed, very hot gas "river" which can reach 400 MPH as it races down the mountainside. This pyroclastic flow, rather than lava itself, is the real danger being near an active volcano. The most recent fatalities, in 2001, were from pyroclastic flow. Centaura maintains a respectful distance from the active areas.
Arenal is the newest in the chain of very active volcanoes forming the main spine of Costa Rica. Arenal was constructed by successive eruptions of the older Chatto volcano, which now has a beautiful lake filling its caldera (the "caldera" is the cone in the top of an extinct volcano). This is a popular, albeit very rugged, hiking place, with great views of active Arenal nearby.
In 1995 Arenal Volcano was 1657 meters (5435 feet) high and constantly growing. It is a very young volcano (indeed, all of Central America's land bridge was pushed up from the ocean floor by tectonic plates long after the dinosaurs disappeared). The type of volcano is called "stratovolcano" because it keeps growing upwards, and is the type known as andesitic (forming the Andes range).
The earliest known eruptions of Arenal took place about 7,000 years ago, and the two volcanoes, Arenal and Chatto, were active concurrently until the activity of Chatto ended about 3,500 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone.
Arenal's most recent eruptive period began with a major explosive eruption in 1968 (you can visit the memorial, on the farm, built to honor those killed in the 1968 eruption). Continuous explosive eruption activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows (avalanche of hot gases, rocks and ashes) has occurred since then from vents at the summit and on the upper western flank. It's eruptions are of the strombolian type (name after the volcano Stromboli in Italy: A type of volcanic activity which produces frequent, moderate eruptions.Lake Arenal, next to the volcano, is mainly man-made for one of Costa Rica's hydroelectric projects. It is a mecca for wind surfers and sport fishermen, seeking the famous "Guapote", the fighting rainbow bass.