Analysis of the spatiotemporal distribution of the ash fall of the Turrialba Volcano (2010 - 2018), Costa Rica: isofrequency, volume and effects

Abstract

The Turrialba volcano began its eruptive period at the beginning of 2010 (area with reports of ash: 624 km2), which has been maintained until the present (July 2018). The highest activity occurred at the end of October 2014, gradually increasing until reaching a maximum in 2016 (12,887 km2) that is, in six years the impact area due to ash fall increased by 21 times its size, and decreased from that year onward. According to the isofrequency maps of ash fall, it was determined that the Great Metropolitan Area, in the SW direction, was the area of the country most affected by ash fall (87.8 % of the reports). This area includes Vázquez de Coronado, Guadalupe, Moravia, San Pedro de Montes de Oca, Curridabat, Zapote, Tibás and San José. It is closely followed by sectors located in the NW direction (7.2 %), as well as SE and NE (2.9 % and 2.1 %), respectively. The months of May and October were when there were more eruptions. Regarding the effects of the ashes on air traffic, of the total number of relevant eruptions in the Turrialba, only 0.5 % merited the closure of air traffic at the Juan Santamaría International Airport, which corresponded to 53 % of the time ash was recorded in Rio Segundo. The Tobías Bolaños airport, merited only 8 % of the closures with respect to the reports of ash fall. A total of 6 reports of ash fall were recorded from the period 2010-2017 for the planned location of the future Metropolitan International Airport of Costa Rica (Orotina), so it could be speculated that it will only require 1 or 2 air traffic closures. The estimated total ash volume is 8.5 ± 0.5 x 106 m3 (0.008 - 0.009 km3), which, despite being a very small eruptive volume, generated considerable economic losses.