The timescale and mechanisms of fault sealing and water‐rock interaction after an earthquake
Abstract Hydrogeochemical monitoring of a basalt‐hosted aquifer, which contains Ice Age meteoric water and is situated at 1220 m below sea level in the Tjörnes Fracture Zone, northern Iceland, has been ongoing since July 2002. Based on hydrogeochemical changes following an earthquake of magnitude (M...
| Published in: | Geofluids |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2007
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/j.1468-8123.2007.00197.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1468-8123.2007.00197.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1468-8123.2007.00197.x |
| Summary: | Abstract Hydrogeochemical monitoring of a basalt‐hosted aquifer, which contains Ice Age meteoric water and is situated at 1220 m below sea level in the Tjörnes Fracture Zone, northern Iceland, has been ongoing since July 2002. Based on hydrogeochemical changes following an earthquake of magnitude (M w ) 5.8 on 16 September 2002, we constrained the timescales of post‐seismic fault sealing and water–rock interaction. We interpret that the earthquake ruptured a hydrological barrier, permitting a rapid influx of chemically and isotopically distinct Ice Age meteoric water from a second aquifer. During the two subsequent years, we monitored a chemical and isotopic recovery towards pre‐earthquake aquifer compositions, which we interpret to have been mainly facilitated by fault‐sealing processes. This recovery was interrupted in November 2004 by a second rupturing event, which was probably induced by two minor earthquakes and which reopened the pathway to the second aquifer. We conclude that the timescale of fault sealing was approximately 2 years and that the approach to isotopic equilibrium (from global meteoric water line) was approximately 18% after >10 4 years. |
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