Three earthquakes with magnitudes 1.2 to 1.9 degrees shook the base of active landslide in the southwest wall of Irazú Volcano.
As reported by the Seismological and Volcanological Observatory of Costa Rica (OVSICORI) of the National University (UNA), the movements occurred on March 16th.
The sliding of material in the wall of the colossus was detected since 2004, but in recent years it has caused concern because it risks the telecommunication towers that emit signals for the Greater Metropolitan Area (GAM) and a large part of the country.
A report published by OVSICORI, dated November 20th 2018, indicates that since December 2014 several important collapses occurred in that area.
Around 20 million cubic meters collapsed [on December 17th 2014], generating a wave of more than 50 meters high in the first kilometer of the route. The collapsed material reached a distance of four kilometers, according to aerial observation. Then, on June 15th, 2015, a new 1.5 million cubic meters collapse occurred […] Since then, numerous minor collapses have occurred,”
said the report prepared by geologists Cyril Muller and Mario Angarita.
The main consequence of these collapses is the destabilization of the last 100 or 200 meters of the material platform that holds the telecommunications antennas.
Between August 2015 and March 2018, scientists conducted campaign measurements on several sites around the main crack and since May 2018 a permanent GPS antenna was installed.
In general, it is observed that to the west of the main crack there is a 20-to-50-centimeter movement towards the west-northwest per year, and a vertical 25-to-55-centimter movement per year.
The different analyzes carried out by the experts foresee that the date of rupture of the landslide would occur in one to eight years from now.