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Horálek, Josef; Šı́lený, Jan; Fischer, Tomáš; Slancová, Alice; Boušková, Alena

doi:10.1023/a:1021811600752

Cited by 42 publications

(6 citation statements)

References 14 publications

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“…Before 2008, the most intense swarm occurred in 1985/1986 with more than 8,000 recorded events and M L,max = 4.5 (Neunhöfer and Meier 2004). The swarm in January 1997 consisted of more than 1,800 events with M L,max = 3.0 (Horálek et al 2000b). There, the activity clustered in two subclusters with different types of source mechanisms, whereas one type comprised volumetric source changes (tensile earthquakes) and the other one showed pure shear faulting (Vavryčuk 2002).…”

Section: Introductionmentioning

confidence: 97%

Monitoring the West Bohemian earthquake swarm in 2008/2009 by a temporary small-aperture seismic array

2011

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The most recent intense earthquake swarm in West Bohemia lasted from 6 October 2008 to January 2009. Starting 12 days after the onset, the University of Potsdam monitored the swarm by a temporary small-aperture seismic array at 10 km epicentral distance. The purpose of the installation was a complete monitoring of the swarm including micro-earthquakes (M L < 0). We identify earthquakes using a conventional shortterm average/long-term average trigger combined with sliding-window frequency-wavenumber and polarisation analyses. The resulting earthquake catalogue consists of 14,530 earthquakes between nitudes in the range of −1.2 ≤ M L ≤ 2.7. The small-aperture seismic array substantially lowers the detection threshold to about M c = −0.4, when compared to the regional networks operating in West Bohemia (M c > 0.0). In the course of this work, the main temporal features (frequencymagnitude distribution, propagation of back azimuth and horizontal slowness, occurrence rate of aftershock sequences and interevent-time distribution) of the recent 2008/2009 earthquake swarm are presented and discussed. Temporal changes of the coefficient of variation (based on interevent times) suggest that the swarm earthquake activity of the 2008/2009 swarm terminates by 12 January 2009. During the main phase in our studied swarm period after 19 October, the b value of the Gutenberg-Richter relation decreases from 1.2 to 0.8. This trend is also reflected in the powerlaw behavior of the seismic moment release. The corresponding total seismic moment release of 1.02 × 10 17 Nm is equivalent to M L,max = 5.4.

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Section: Introductionmentioning

confidence: 97%

Monitoring the West Bohemian earthquake swarm in 2008/2009 by a temporary small-aperture seismic array

2011

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“…Seismohydrological precursor 11 effects could also be observed on this occasion but with different characteristics than in 2000. 12 Thus, it became possible to compare and contrast these two most important swarmquake 13 periods of the recent past from both a seismological as well as a seismohydrological point of 14 view. Such a comparison, however, is only by its nature semi-quantitative.…”

mentioning

confidence: 99%

“…In the present case, this is expressed by different time 10 spans between the hydrological anomalies and earthquakes (12 to 36 days) and the shape and 11 duration of the anomalies (a few days to 8 months). Therefore, it is not possible at present to 12 derive a systematic relationship between anomaly occurrence and seismic activity, as proposed 13 within the common earthquake prediction debate (e.g. Nature, February/March 1999).…”

mentioning

confidence: 99%

Seismohydrological effects related to the NW Bohemia earthquake swarms of 2000 and 2008: Similarities and distinctions

Koch

Heinicke

2011

Journal of Geodynamics

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“…7), and swarm-like character of the earthquakes has been observed in many regions of the world (e.g., Hill et al, 1985;Dorel et al, 1995 andreview in Špičák, 2000). In the western part of the Bohemian Massif, where Cainozoic volcanic activity and fluid migration is also typical, microswarms and swarms with an unusually large number of events were described (e.g., Skácelová et al, 1995;Horálek et al, 2000). The most intense seismic activity in western Bohemia is concentrated in a relatively narrow zone where swarms of typically several hundreds to thousands of micro-earthquakes occur within a volume of only a few cubic kilometres (Nový Kostel focal zone).…”

Section: Nysa-morava Fault Zone and Origin Of Seismicitymentioning

confidence: 99%

“…The most intense seismic activity in western Bohemia is concentrated in a relatively narrow zone where swarms of typically several hundreds to thousands of micro-earthquakes occur within a volume of only a few cubic kilometres (Nový Kostel focal zone). Several subordinate focal zones with a much lower number of earthquakes (up to several dozens during individual micro-swarms) and with maximum magnitudes of 1.0 to 2.5 has been described, too (Horálek et al, 2000;V. Nehybka, IPE, personal communication, 2000−2004.…”

Section: Nysa-morava Fault Zone and Origin Of Seismicitymentioning

confidence: 99%

Present-day seismicity of the south-eastern Elbe Fault System (NE Bohemian Massif)

et al. 2006

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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 deepseated 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.

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Untitled

Cited by 42 publications

References 14 publications

Monitoring the West Bohemian earthquake swarm in 2008/2009 by a temporary small-aperture seismic array

Monitoring the West Bohemian earthquake swarm in 2008/2009 by a temporary small-aperture seismic array

Seismohydrological effects related to the NW Bohemia earthquake swarms of 2000 and 2008: Similarities and distinctions

Present-day seismicity of the south-eastern Elbe Fault System (NE Bohemian Massif)

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