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| Titel |
Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling |
| VerfasserIn |
O. Ahmadi, C. Juhlin, M. Ask, B. Lund |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 2 ; Nr. 6, no. 2 (2015-06-03), S.621-632 |
| Datensatznummer |
250115455
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| Publikation (Nr.) |
 copernicus.org/se-6-621-2015.pdf |
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| Zusammenfassung |
| A new seismic reflection survey for imaging deeper levels of the end-glacial
Pärvie fault system in northern Sweden was acquired in June 2014. The
Pärvie fault system hosts the largest fault scarp so far documented in
northern Scandinavia, both in terms of its length and calculated magnitude of
the earthquake that generated it. Present-day microearthquakes occur along
the length of the fault scarp on the eastern side of the scarp, in general
agreement with an east-dipping main fault. In the central section of the
fault system, where there is a number of subsidiary faults east of the main
Pärvie scarp, it has been unclear how the earthquakes relate to the
structures mapped at the surface. A seismic profile across the Pärvie
fault system acquired in 2007, with a mechanical hammer as a source, showed a
good correlation between the surface mapped faults and moderate to steeply
dipping reflections. The most pronounced reflectors could be mapped to about
3 km depth. In the new seismic survey, for deeper penetration an explosive
source with a maximum charge size of 8.34 kg in 20 m deep shot holes was
used. Reflectors can now be traced to deeper levels with the main 65°
east-dipping fault interpreted as a weakly reflective structure. As in the
previous profile, there is a strongly reflective 60° west-dipping
structure present to the east of the main fault that can now be mapped to
about 8 km depth. Extrapolations of the main and subsidiary faults converge
at a depth of about 11.5 km, where current earthquake activity is
concentrated, suggesting their intersection has created favorable conditions
for seismic stress release. Based on the present and previous seismic
reflection data, we propose potential locations for future boreholes for
scientific drilling into the fault system.
These boreholes will provide a better understanding of the reflective nature
of the fault structures and stress fields along the faults at depth. |
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