Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling
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...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-06-01
|
| Series: | Solid Earth |
| Online Access: | http://www.solid-earth.net/6/621/2015/se-6-621-2015.pdf |
| _version_ | 1819017965166657536 |
|---|---|
| author | O. Ahmadi C. Juhlin M. Ask B. Lund |
| author_facet | O. Ahmadi C. Juhlin M. Ask B. Lund |
| author_sort | O. Ahmadi |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-21T03:11:54Z |
| format | Article |
| id | doaj.art-71f2676f2f7c4ec1a26da826ecaf89e9 |
| institution | Directory Open Access Journal |
| issn | 1869-9510 1869-9529 |
| language | English |
| last_indexed | 2024-12-21T03:11:54Z |
| publishDate | 2015-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Solid Earth |
| spelling | doaj.art-71f2676f2f7c4ec1a26da826ecaf89e92022-12-21T19:17:57ZengCopernicus PublicationsSolid Earth1869-95101869-95292015-06-016262163210.5194/se-6-621-2015Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profilingO. Ahmadi0C. Juhlin1M. Ask2B. Lund3Department of Earth Sciences, Uppsala University, Villavägen 16, 752 36 Uppsala, SwedenDepartment of Earth Sciences, Uppsala University, Villavägen 16, 752 36 Uppsala, SwedenDepartment of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971 87 Luleå, SwedenDepartment of Earth Sciences, Uppsala University, Villavägen 16, 752 36 Uppsala, SwedenA 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.http://www.solid-earth.net/6/621/2015/se-6-621-2015.pdf |
| spellingShingle | O. Ahmadi C. Juhlin M. Ask B. Lund Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling Solid Earth |
| title | Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling |
| title_full | Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling |
| title_fullStr | Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling |
| title_full_unstemmed | Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling |
| title_short | Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling |
| title_sort | revealing the deeper structure of the end glacial parvie fault system in northern sweden by seismic reflection profiling |
| url | http://www.solid-earth.net/6/621/2015/se-6-621-2015.pdf |
| work_keys_str_mv | AT oahmadi revealingthedeeperstructureoftheendglacialparviefaultsysteminnorthernswedenbyseismicreflectionprofiling AT cjuhlin revealingthedeeperstructureoftheendglacialparviefaultsysteminnorthernswedenbyseismicreflectionprofiling AT mask revealingthedeeperstructureoftheendglacialparviefaultsysteminnorthernswedenbyseismicreflectionprofiling AT blund revealingthedeeperstructureoftheendglacialparviefaultsysteminnorthernswedenbyseismicreflectionprofiling |