Record details

Title
    Seismicity and stress field in the vicinity of the KTB location
Statement of responsibility
    H.A. Dahlheim, H. Gebrande, E. Schmedes, H. Soffel
Other titles
    The KTB Deep Drill Hole (Variant.)
Author
    Dahlheim, H. A.
    Gebrande, H.
    Schmedes, E.
    Soffel, H.
Language
    anglicky
Source title - serial
    Journal Geophysical Research
Vol./nr.
    Vol. 102, no. B8
Pages
    p. 18493-18506
Year
    1997
Notes
    8 obr., 4 tab., 2 s.bibl.
    Zkr. název ser.: J. geophys. Res. (Washington)
Subject group
    Český masiv
    hypocentrum
    krystalinikum
    kůra kontinentální
    napětí
    ohniskový mechanismus
    seizmická stanice
    seizmotektonika
    vrt hluboký
    zemětřesení
Geographical name
    ČR-Čechy
    Karlovy Vary
    Kraslice (Sokolov)
    Mariánské Lázně (Cheb)
    Nový Kostel (Cheb)
    Skalná (Cheb)
    SRN
Keyword
    Field
    KTB
    Location
    Seismicity
    Stress
    Vicinity
Abstract (in english)
   A local, broadband, seismic network of four observatory-quality stations (KTB-NET) was operated during the drilling of the KTB hole, within the framework of the interdisciplinary German Continental Deep Drilling Program (KTB). The aim was to investigate the seismic activity with regard to the tectonic stress field and to compare it with data from in situ measurements in the 9.1-km deep borehole sections (bottom temperature of 260 C and heat flow of 82-85 mW/m2). From October 1990 to November 1995, over 80 local microearthquakes with magnitudes from 0.2 to 2.8 ML were recorded: eight small events by the KTB-NET only and four erthquake swarms with 73 events by the KTB-NET and stations of the Vogtland/Western Bohemia networks. Six of the small events are located within or close to the KTB-NET.
   The swarm events occurred at the southwestern extension of the Ohre rift, in an area 20 km north of the drill site, which is revealed to be part of the Vogtland/Western Bohemia seismotectonic unit, characterized by swarm activity. The hypocenters are limited to the upper 13 km of the crust, with a distinct concentration between 10 and 12 km. All types of fault plane solutions are found, but at depths greater than 8 km, reversed faulting mechanisms predominate. P axes are very uniformly oriented in NNW-SSE direction, corresponding to the well-known regional stress orientation in central Europe and in agreement with the special in situ stress measurements of the KTB program. The local mechanism of a ML=1.2 event induced by a fluid injection experiment fits into the result obtained from the natural events. Possible indications for the brittle-ductile transition are discussed in view of the observed in view of the observed earthquake depth and focal mechanism distributions
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    23. 1. 2008
Import date
    8. 8. 2012