Irazu: Slope collapsed in crater area

The slope in the fog. © OVSICORI

In the crater area of Irazu Volcano, a large part of the slope has collapsed and slipped down. According to OVSICORI expert Cyril Muller, there were at least 100 small landslides on August 25th. A crack in the slope had widened by 40 centimeters. Yesterday morning the big landslide occurred, in which several million cubic meters of material slid down. Due to the bad weather conditions, there are only pictures of the edge of the landslide so far. It manifested itself at the border of an antenna park. 2 containers with transmission equipment were torn into the depths. The rest of the antenna equipment is now directly at the edge of the slide and could still slide down. The antenna park is located southwest of the crater, on a ridge that ends directly at the crater rim.

The event was not unexpected. Already in May 2019 a major landslide occurred. At that time, the main crater to the north was affected and a 10 m high tidal wave was triggered in its crater lake. In the meantime the crater lake had practically disappeared. Scientists observed the increasing crack formation in the crater walls for a long time.

The Irazu is located a few kilometers east of the capital San José and is with a height of 3.432 m the highest volcano in Costa Rica. The last eruption was in 1994 and due to the current development the alarm status is set to “red”. Sudden changes in the load of the volcano could lead to pressure changes inside the volcano and trigger eruptions. In addition, deeply descending crevasses could open. However, there is no evidence that there is an active magma body under the volcano. Therefore an immediate eruption is unlikely.