Present-day Seismicity of the Southeastern Elbe Fault System (NE Bohemian Massif)

ŠPAČEK, Petr, Zdeňka SÝKOROVÁ, Jana PAZDÍRKOVÁ, Jan ŠVANCARA and Josef HAVÍŘ. Present-day Seismicity of the Southeastern Elbe Fault System (NE Bohemian Massif). Studia geophysica et geodaetica. Praha: Geofyzikální ústav AV ČR, 2006, vol. 50, No 4, p. 233-258, 25 pp. ISSN 0039-3169.

Basic information

• Original name: Present-day Seismicity of the Southeastern Elbe Fault System (NE Bohemian Massif)
• Name in Czech: Recentní seismicita jihovýchodní části labského zlomového systému (sv. část Českého masivu)
• Authors: ŠPAČEK, Petr (203 Czech Republic, guarantor), Zdeňka SÝKOROVÁ (203 Czech Republic), Jana PAZDÍRKOVÁ (203 Czech Republic), Jan ŠVANCARA (203 Czech Republic) and Josef HAVÍŘ (203 Czech Republic).
• Edition: Studia geophysica et geodaetica, Praha, Geofyzikální ústav AV ČR, 2006, 0039-3169.

Other information

• Original language: English
• Type of outcome: Article in a journal
• Field of Study: 10507 Volcanology
• Country of publisher: Czech Republic
• Confidentiality degree: is not subject to a state or trade secret
• Impact factor: Impact factor: 0.603
• RIV identification code: RIV/00216224:14310/06:00015851
• Organization unit: Faculty of Science
• UT WoS: 000237665100005
• Keywords in English: Sudetes; Bohemian Massif; Elbe Fault System; seismicity; fault activity; focal mechanisms; fluids
• Tags: Bohemian massif, Elbe Fault System, fault activity, fluids, focal mechanisms, seismicity, Sudetes

Abstract

The Variscan Bohemian Massif is disrupted by the NW-SE striking Elbe Fault System in its northern part. The increased tectonic activity associated with this structure is manifested by increased seismicity in the eastern part of the Sudetes. With the use of a temporary local seismic network, the total number of micro-earthquakes located in this region increased to 153 for the period 1996-2003. The local magnitudes vary between -0.6 and 1.8 and the seismic energy was often released in swarm-like sequences. Five seismic events with well-defined P-onset polarities at five or six stations enabled the estimation of focal mechanisms. The present-day activity of the WNW-ESE to NNW-SSE fault systems is discussed on the basis of source mechanisms, the alignment of the epicentres, as well as morphological and geological evidence. The majority of the recent seismic activity is concentrated in a 40-60 km wide zone of a generally NW-SE trend. This structure represents a regional zone of weakness within the SE termination of the Elbe Fault System, defined by a mesh of interconnected faults, of which many are deep-seated and highly permeable and some are associated with light to moderate historical earthquakes. Both in the areas due south and due north of this zone the present-day seismic activity is very low. The increased tectonic activity can be interpreted as a result of the abundance of suitably oriented faults and their interconnection into major fault systems, the proximity of the Outer Carpathian indentor and the Cainozoic volcanic and associated recent post-volcanic activity. The similar character of swarms and their coincidence with the post-volcanic activity in the southeastern part of the Elbe Fault System and in some focal zones of the western Bohemian seismically active area suggests that overpressurized fluids may represent a potential swarm-triggering mechanism.

Abstract (in Czech)

The Variscan Bohemian Massif is disrupted by the NW-SE striking Elbe Fault System in its northern part. The increased tectonic activity associated with this structure is manifested by increased seismicity in the eastern part of the Sudetes. With the use of a temporary local seismic network, the total number of micro-earthquakes located in this region increased to 153 for the period 1996-2003. The local magnitudes vary between -0.6 and 1.8 and the seismic energy was often released in swarm-like sequences. Five seismic events with well-defined P-onset polarities at five or six stations enabled the estimation of focal mechanisms. The present-day activity of the WNW-ESE to NNW-SSE fault systems is discussed on the basis of source mechanisms, the alignment of the epicentres, as well as morphological and geological evidence. The majority of the recent seismic activity is concentrated in a 40-60 km wide zone of a generally NW-SE trend. This structure represents a regional zone of weakness within the SE termination of the Elbe Fault System, defined by a mesh of interconnected faults, of which many are deep-seated and highly permeable and some are associated with light to moderate historical earthquakes. Both in the areas due south and due north of this zone the present-day seismic activity is very low. The increased tectonic activity can be interpreted as a result of the abundance of suitably oriented faults and their interconnection into major fault systems, the proximity of the Outer Carpathian indentor and the Cainozoic volcanic and associated recent post-volcanic activity. The similar character of swarms and their coincidence with the post-volcanic activity in the southeastern part of the Elbe Fault System and in some focal zones of the western Bohemian seismically active area suggests that overpressurized fluids may represent a potential swarm-triggering mechanism.

Links

• GP205/02/D139, research and development project: Name: Seismické a reologické vlastnosti spodnokorových hornin a jejich podíl na anizotropii litosféry

Investor: Czech Science Foundation, Seismic and rheological features of the lower crustal rocks and their contribution to the anizotropy of the litosphere

• MSM0021622412, plan (intention): Name: Interakce mezi chemickými látkami, prostředím a biologickými systémy a jejich důsledky na globální, regionální a lokální úrovni (INCHEMBIOL) (Acronym: INCHEMBIOL)

Investor: Ministry of Education, Youth and Sports of the CR, Interactions among the chemicals, environment and biological systems and their consequences on the global, regional and local scales (INCHEMBIOL)