Digital Research Space of Induced Seismicity for EPOS Purposes (IS-EPOS project)

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1 Digital Research Space of Induced Seismicity for EPOS Purposes (IS-EPOS project) The project IS-EPOS ( was financed from Polish structural funds (POIG /13-00) in the years The project IS-EPOS was run by the consortium led by Institute of Geophysics Polish Academy of Sciences (IGF PAS) and partnered by Academic Computer Center Cyfronet AGH (ACK CYFRONET), Central Mining Institute (GIG) and an industrial partner Coal Company (KWSA). The main goal of the project was to build digital platform of seismicity induced or triggered by human technological activity which under certain circumstances can become hazardous for people, infrastructure and the environment. The relevant seismic and non-seismic data are gathered in the so-called episodes of induced seismicity. The IS-EPOS platform integrates presently six episodes of anthropogenic seismicity respectively linked to underground mining in Poland, hydroelectric energy production and geothermal energy production experiments in Germany. The IS-EPOS platform is a prototype of the Thematic Core Services (TCS) Anthropogenic Hazards (AH) belonging to the pan-european multidisciplinary research platform created within the European Plate Observing System (EPOS) program. The Central Mining Institute (GIG) research team of the Depatment of Geology and Geophysics - managed task 4 and elaborated two episodes, ESI-1 and ESI-6. The Episode ESI-1, virtual laboratory of mining induced seismicity, was elaborated together with Coal Company. Description of ESI-1 and ESI-6 episodes ESI-1: BOBREK MINE: seismicity linked to longwall mining Logo ESI-1 ESI-1 is the Laboratory for Monitoring Mining Induced Seismicity (LMMIS) of passive seismic records of seismicity induced and triggered by underground coal mining. 1. Technical conditions that induce seismicity Seismic activity linked to longwall mining of panel 3 in coal seam 503 in Bobrek colliery in Upper Silesia Coal Basin in Poland. The coal seam no. 503 was 3.0 to 3.5 m thick in the area of longwall panel no.3 and at the depth of 700m below surface. The coal extraction was carried on in the period 1/4/2009-8/07/ Episode time period The episode time period: from 1/04/2009 to 8/07/ The types of data and their characteristics Seismic data: LMMIS lab possesses all history of the triggered digital waveforms of seismic events recorded during the mining of the longwall panel, both recorded underground close to the seismic 1

2 sources (near field data) as well as those from surface seismic stations in the far wave field. The SOS underground Bobrek seismic network consists of 14 uniaxial 1Hz geophones and 6 triaxial 1Hz geophones and GRSS GIG surface seismic network consist of 10 triaxial 1Hz seismometers. Seismic catalog contains 2,996 seismic events in energy/magnitude range 1E2J (M L =0.1) and 8E8J (M L =3.7). Technological data: front line advance, edges of mined area, map of longwall panel No 3/503, maps of all coal seams Geological data: lithological profile, geotechnical rock parameters, static geological 3D model Data ownership: Central Mining Institute (GIG) and Coal Company (KWSA) Poland. General information on seismicity in Bobrek mine In 2010 the output of the mines of Coal Company amounted to 39.5 million tonnes of coal, i.e % of Poland s total output. Most of the mines of Coal Company S.A. are characterised by a high level of rock burst hazard. Coal Company mines are located in the Upper Silesian Coal Basin in south part of Poland. These are underground mines which operate in difficult geological conditions at great depths of up to 1 200m. The location of Bobrek mine is presented on Figure 1. Fig. 1. Location of Coal Company SA and Bobrek mine The coal seam no. 503 was 3.0 to 3.5 m thick in the area of longwall panel no.3 and 700m deep under surface. The total volume of the mined coal was approximately m 3. Beyond the southern terminus face line of the longwall no 3, the geological layers in the sideslope of the basin dip steeply. Hard coal mining in the area of the Bytom Syncline (North part of Upper Silesia Coal Basin under Bytom City) has been associated with the occurrence of high energy seismic events (up to 10 9 J, local magnitude M L up to 4.0), which have been recorded by the local mining seismological network and regional seismological network. The Seismic Observation System (SOS) in the Bobrek mine, designed by the Central Mining Institute (GIG), has 64 channels. The network consists of 1 Hz triaxial and 1 Hz uniaxial geophones and a recording system that allows the hypocentres to be located. The network consists of 32 short period seismometers (fig. 2), which work with frequency range 1 500Hz. The tremors that occurred during excavation of longwall panel 3/503 were first observed in April 2009 and continued until In total, there were mining seismic events with a seismic energy greater than 10 2 J (local magnitude M L >0.1). The strongest tremor during the mining, with a seismic energy level of J (M L =3.7), took place on when the longwall face line approached the syncline axis. 2

3 Fig. 2. Distribution of seismic events during excavation of longwall panel no. 3 in Bobrek Mine. Blue diamonds depict the deploy of underground seismic stations. The biggest seismic events were also recorded by some surface seismic stations worked in Upper Silesian regional seismic network (GRSS GIG). The distribution of seismic activity (Fig. 3) during excavation of longwall 3/503 shows greatest amount of seismic events at time when the panel approaching the syncline axis. Fig. 3. Distribution of the hypocentres of seismic events during excavation of longwall panel 3/503 from 1 May 2009 to 8 July ESI-6 USCB: regional seismicity and ground motion associating underground coal mining Logo ESI-6 3

4 ESI-6 is a permanent seismic observations by the Upper Silesian Seismic Network (GRSS EPOS) for monitoring mining induced seismicity in Polish part of Upper Silesia Coal Basin. 1. Technical conditions that induce seismicity Seismic activity linked to coal mining in Upper Silesia Coal Basin (USCB) in Poland. More than 20 seismic prone mines. Multilevel mine operations have been conducted in the Upper Silesian Coal Basin for longer than 200 years. 2. Episode time period The episode time period: from 1/01/ The types of data and their characteristics Seismic data: All digital triggered and continuous seismic records in MiniSeed format as well as seismic catalogue are available for this episode since Additionally model of wave velocity is available and seismic activity is presented on the website: The GRSS EPOS permanent surface seismic network consist of 10 triaxial stations deployed in USCB (5 sec velocity seismometers VE-53 BB manufactured by GeoSIG). The highest magnitude in catalog, M L =4.1 and a few hundred mining seismic events with magnitude M L 2.0 per year. Ground motion data: Digital triggered ground motion data recorded by portable civil engineering stations and linked by ID with seismic catalog. Five surface accelerometers and two fixed in boreholes. Seismic data dedicated for civil engineering purposes. Ground motion parameters since 2014 and Vs30 wave velocity under seismic stations are available for this episode. Technological data: Layer with mines boundary area in Upper Silesia Geological data: Layer with regional faults in USCB, geological cross-sections Data ownership: Central Mining Institute (GIG) Poland. Fig. 4. Distribution of seismic events induced by mining with magnitude M>1.7 in Upper Silesia Coal Basin from 1980 to 2015 General information on seismicity in Upper Silesian Coal Basin Over 1000 tremors with a local magnitude M L >1,5 as well as ten and several thousand weaker tremors occur in the Upper Silesian Coal Basin yearly. In the epicentre areas strong mining tremors cause slight damaging effect in buildings and fear among the people. It is very important to study 4

5 vibration parameters on the surface as well as response of buildings and infrastructures to impact of strong mining seismic events. Up till now in the Upper Silesia Coal Basin the maximum values of the PGV ground motion in the epicentre zone amounted to 100 mm/s, whereas PGA 2,8 m/s 2. 5