Arenal Volcano History - Page #3 "A Natural Wonder"

Since 1968, Arenal has continualy emitted gas and water vapor. There have also been pyroclastic explosions, some are accompanied by powerful thun¬dering.
The emitted ash is carried by the wind to long distances, generally to the northwest. The largest and heaviest material falls closer to the crater.
Lava flows are frequently observed; they exit the crater at about 1000 degrees Centigrade, as the lava travels down it looss heat as an example, the lava in this picture was 600 degrees C and it had traveled 400m from the vent.
Pyroclastic flows are the greatest volcanic risk at Arenal. These flows descend the flanks of the volcano with very high temperatures and velocities of approximately 120 kph, obliterating everything in their path. This photographic sequence shows a flow on March 11, 1988 at 09:35 a.m. It was originated in crater C and traveled down the south flank, termi¬nating 1 km from the vent.
When lava travels and cools, blocks of different sizes form and the flow can develop a channel in the middle.

On August 28. 1993 at 08:20 p.m. the northwest wall of crater C collapsed producing to several pyroclastic flows. The collapsed crater wall had a V-shape, it was approximately 60 m deep and 100 m wide, this is the location that new lava flows began to be issued. In March 1994. the flows continued in the same direction and were depositing materials around the crater. In 1996 the V- shape was filled and the crater took its previous shape.
During 1968 Arenal Volcano was a single cone, towards the W (right) a gas column may be observed on crater A.
In 1978, only one cone could be obeserved, where crater D located at 1633 m.a.s.l. The so-called active crater C,was at 1450 m.a.s.l.
In the photograph taken December 2, 1995 crater D, to the left, was quiet and had only small gas emissions. To the right, Crater C was emitting pyroclasts and lava flows.
With the improvement of the road Ciudad Quesada-Fortuna, the number of local and foreing visitors increased. Today it is possible to find many tourist facilities in Fortuna a special town with very friendly inhabitants.