Earthquake-enhanced permeability – evidence from carbon dioxide release following the ML3.5 earthquake in West Bohemia

0479549 - GFÚ 2018 RIV NL eng J - Journal Article
Fischer, Tomáš - Matyska, C. - Heinicke, J.
Earthquake-enhanced permeability – evidence from carbon dioxide release following the ML3.5 earthquake in West Bohemia.
Earth and Planetary Science Letters. Roč. 460, February (2017), s. 60-67. ISSN 0012-821X. E-ISSN 1385-013X
R&D Projects: GA MŠMT LM2010008
Institutional support: RVO:67985530
Keywords : earthquake swarms * fluid triggering * crustal CO2 * fault valve
OECD category: Volcanology
Impact factor: 4.581, year: 2017

The West Bohemia/Vogtland region is characterized by earthquake swarm activity and degassing of CO2 of mantle origin. A fast increase of CO2 flow rate was observed 4 days after a M-L 3.5 earthquake in May 2014 in the Hartousov mofette, 9 km from the epicentres. During the subsequent 150 days the flow reached sixfold of the original level, and has been slowly decaying until present. Similar behavior was observed during and after the swarm in 2008 pointing to a fault-valve mechanism in long-term. Here, we present the results of simulation of gas flow in a two dimensional model of Earth's crust composed of a sealing layer at the hypocentre depth which is penetrated by the earthquake fault and releases fluid from a relatively low-permeability lower crust. This simple model is capable of explaining the observations, including the short travel time of the flow pulse from 8 km depth to the surface, long-term flow increase and its subsequent slow decay. Our model is consistent with other analyse of the 2014 aftershocks which attributes their anomalous character to exponentially decreasing external fluid force. Our observations and model hence track the fluid pressure pulse from depth where it was responsible for aftershocks triggering to the surface where a significant long-term increase of CO2 flow started 4 days later.
Permanent Link: http://hdl.handle.net/11104/0275530