Arenal Volcano History:
Arenal Volcano was formerly known as Cerro Arenal, Pan de Azucar volcano Canaste, or Hill of the Guatusos, is an imposing and beautiful in an almost conical stratovolcano, located at 17km. northwest of La Fortuna, its area is 33km ².
Arenal its name from the fact that the lava flows to suffer dislocation physical-chemical effect, develop lithic and crystal sands that are deposited at the bottom of the cone on the plains of the channels, also contribute to pyroclastic flows.
Arenal cone before 1968 showed a thick cover and had a single crater at its summit, which had fumarolic activity. On July 29, 1968 the volcano became active eruption at 7:20 am, local time, with an explosion type pelean that formed the crater A, about 1000m.snm, this gave glowing avalanches reached blocks that two villages at the foot of the volcano, killing about 87 people.
The gas temperatures were so high that came to dehydrate and carbonize the vegetation from 29 to 31 July, three new craters were formed: the B 170m.snm some 1, the smallest and in 1974 the activity migrates to the crater 400m.snm C to 1, with intermediate size compared to the other two.
Has grown by collapse of its walls at the expense of the west wall of crater D which gradually coalesce to form a crater compound. The fourth and final D is the crater, located at the top and above others. Currently there are craters C and D. The emission of pyroclastic flows is the biggest risk associated with the Arenal, since the materials column collapses and falls with high temperatures and average speeds of 120 km / h destroying everything that his step.
The ash is carried away by the wind increased, mainly to the west and northwest. The larger, heavier materials such as blocks fall near the crater. The lava flows are observed constantly, leaving average temperatures of 1000 º C, lose as temperatures drop. When cooled, the building blocks of different sizes and leave a channel morphology.
The Arenal Volcano is the youngest of a group of volcanoes aligned, in which the activity has been migrating from South to North or the Hill The Lost, a complex and eroded volcano, Cerro Chato, a truncated cone with a lake inside the crater, and the Arenal. Separated by less than 3 km. This tight alignment of volcanoes may be the result of a fracture following a similar path and is associated with Quaternary volcanism in the area.