Monitoring the effects of seismic energy on the hydrothermal setting of the Irazu Turrialba Volcanic Complex

Objective

In accordance with the Swiss Competence Centre for Energy Research Supply of Electricity (SCCER) Swiss governmental plans for sustainable development of renewable energies, the project “Geophysical and Numerical Experiments for Reservoir Analysis and fluid Transport Energy” (GENERATE - p3.snf.ch/Project-166900) aims to combine numerical solutions and geophysical methods to investigate the geothermal potential of the Great Geneva Basin.

Within this is the study of an active hydrothermal system, subject to frequent seismic energy, giving some fundamental analysis of volcano-seismic interaction in a more sensitive, natural setting. Acting as an ideal “natural laboratory” of hydrothermal processes, the Irazú-Turrialba Volcanic Complex (ITVC) is an ideal location for this aspect of the project.

The Project

The Costa Rica phase of the project aims to understand the interaction between incoming seismic energy from regional earthquakes, and a well-developed hydrothermal system in the ITVC. Furthermore, the project explores the affect this may have on the evolution of the volcanic setting and the potential triggering effects for further hydrothermal activity.

The University of Geneva is responsible, as part of the GENERATE project, for the installation of a network of seismic stations, monitoring the seismicity within the ITVC. This shall involve working alongside the Observatorio Vulcanologico y Sismologico de Costa Rica (OVISCORI - www.ovsicori.una.ac.cr).

As well as the monitoring of seismic activity, the use of ambient noise seismic tomography is a technique implemented to interpret the structure of the volcanic plumbing system beneath both volcanoes.

The aim is to determine the geometric characteristics of the chamber structure, establishing if:

A singular system exists beneath both volcanoes

Completely separate, independent systems exist beneath each volcano

Separate systems with linking conduit(s) exist between each volcano

The Rio Sucio Fault system links or divides the two volcanoes

The Seismic Network

The network itself will consist of 20 seismic stations positioned in and around both National Parks of Irazú and Turrialba, installed using non-invasive methods that shall have no effect on the health of humans, animals or agriculture within the region. Installation of this network shall commence in February 2018 and will remain in the field for a relatively short period lasting approximately 12 months. Each seismic station is composed of a ground motion sensor, a data converter and a power source. When installed in the field, the sensor is stored beneath a bucket and the remaining equipment in a plastic container. There may be a need to dig a small hole, burying the sensor, to reduce the potential ambient noise. A solar panel shall be included if no power grid is available.