The timescale and mechanisms of fault sealing and water-rock interaction after an earthquake

被引:80
作者
Claesson, L. [1 ]
Skelton, A.
Graham, C.
Moerth, C.-M.
机构
[1] Stockholm Univ, Dept Geol & Geochem, S-10691 Stockholm, Sweden
[2] Univ Edinburgh, Sch Geosci, Edinburgh, Midlothian, Scotland
关键词
earthquake; fault sealing; hydrogeochemistry; Iceland; Tjornes Fracture Zone; water-rock interaction;
D O I
10.1111/j.1468-8123.2007.00197.x
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Hydrogeochemical monitoring of a basalt-hosted aquifer, which contains Ice Age meteoric water and is situated at 1220 m below sea level in the Tjornes 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.
引用
收藏
页码:427 / 440
页数:14
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