Analysis of the Impact of the Eruptive Process of the Tungurahua Volcano on the Precipitation Patterns of Hydrographic Microbasins Located Inside and Outside the Zone of Influence

Abstract

The relationship between eruptive processes and precipitation is a topic that lacks research studies, perhaps due to the difficulty that is to have few scenarios, which satisfy conditions for statistical testing. Most of the available literature report a global impact after significant volcanic eruptions. Robock et al. (2008) concluded that the Pinatubo volcano eruption left precipitation consequences in the medium and long term. Kravitz y Robock (2011) suggested considering weather seasons on the estimation of the impact of volcanic eruptions. Allen e Ingram (2002) concluded that volcanic gasses are more important than greenhouse gasses on the climate change at a global level.

In the Ambato river watershed (Ecuador), studies were conducted to evaluate the relationship between eruptive processes of the Tungurahua volcano and the variation in precipitation series. During the main eruptive events between 1999 and 2010, atypical precipitation values were determined during April, May, July, August, and December, with increments within 130.09% and 285.15% with respect to precipitation observations in the studied period (Ríos, 2014).

The results of the present study demonstrate the relationship between rainfall anomalies and volcanic activity. Three watersheds were analyzed: (1) Ambato river watershed, located to the West of the volcano with direct impact of volcanic ash and SO₂; (2) Drenajes Menores of the Pastaza river; and (3) Areas Menores of the Pastaza river. The latter are located to the East of the volcano with no impact from volcanic ash and SO₂ due to the direction of wind flow.