Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8911316 | Journal of Volcanology and Geothermal Research | 2018 | 8 Pages |
Abstract
Seasonal variations in the seismicity of volcanic and geothermal reservoirs are usually attributed to the hydrological cycle. Here, we focus on the Aluto-Langano geothermal system, Ethiopia, where the climate is monsoonal and there is abundant shallow seismicity. We deployed temporary networks of seismometers and GPS receivers to understand the drivers of unrest. First, we show that a statistically significant peak in seismicity occurred 2-3Â months after the main rainy season, with a second, smaller peak of variable timing. Seasonal seismicity is commonly attributed to variations in either surface loading or reservoir pore pressure. As loading will cause subsidence and overpressure will cause uplift, comparing seismicity rates with continuous GPS, enables us to distinguish between mechanisms. At Aluto, the major peak in seismicity is coincident with the high stand of nearby lakes and maximum subsidence, indicating that it is driven by surface loading. The magnitude of loading is insufficient to trigger widespread crustal seismicity but the geothermal reservoir at Aluto is likely sensitive to small perturbations in the stress field. Thus we demonstrate that monsoonal loading can produce seismicity in geothermal reservoirs, and the likelihood of both triggered and induced seismicity varies seasonally.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Yelebe Birhanu, Matthew Wilks, Juliet Biggs, J-Michael Kendall, Atalay Ayele, Elias Lewi,