Studies of induced seismic events clustering in equivalent dimension spaces in chosen Rudna Mine panels

Tyt. z nagłówka.Bibliogr. s. 215-[216].Na podstawie danych o zjawiskach sejsmicznych, które wystąpiły w wybranych oddziałach w ZG Rudna dokonano analizy grupowania się zjawisk w przestrzeni parametrów równoważnych złożonej z wartości dystrybuanty rozkładu parametrów lokalizacji (odległość pomiędzy kolejnymi wstrząsami - dr) i energii (logarytm energii - lE i bezwzględna różnica pomiędzy logarytmami energii kolejnych wstrząsów dlE). Celem tej analizy było sprawdzenie czy przed wystąpieniem zjawiska o dużej energii (powyżej 10/7 J) dochodzi do charakterystycznych zmian rozkładu występowania wstrząsów o mniejszej energii. Analizę oparto o badanie czasowej zmienności wymiaru fraktalnego. Grupowanie się zjawisk odzwierciedla się zmniejszaniem wartości wymiaru fraktalnego. Zmiany w czasie wartości wymiaru fraktalnego przed wystąpieniem silnego zjawiska sejsmicznego mogą wskazywać na występowanie procesu przygotowawczego prowadzącego do wystąpienia silnego zjawiska.The study of clustering of an induced seismic event was carried out to find out whether the temporal clustering of smaller events in different parameters can be observed before and after the high energy events (Ml > 3) from different mining panels of the Rudna Mine. The method chosen for the analysis was a study of the temporal variation of the fractal dimension of the seismic events parameters - the interevent epicentral distance (dr), the interevent time (dt), logarithm of seismic energy (lE) and interevent energy coefficient (dlE). The transformation of seismic source parameters changed into the equivalent dimension (ED) space was done before the temporal behavior studies. The transformation allowed for the estimation of the fractal dimension of different parameters using the same method - correlation fractal dimension, and then easily compares the obtained temporal changes of fractal dimension with different parameters. The effect of clustering is expressed by a decrease of the fractal dimension, which is connected with the similarity of the events parameter and values. The temporal changes of the fractal dimension of seismicity before strongly induced events could then indicate some initiation phase of the process leading to the high energy release.Dostępny również w formie drukowanej.SŁOWA KLUCZOWE: grupowanie zjawisk sejsmicznych, zagrożenie sejsmiczne, kopalnie miedzi, wymiary równoważne. KEYWORDS: seismicity clustering, seismic hazard in mines, copper mines, equivalent dimensions

Seasonal trends and relation to water level of reservoir-triggered seismicity in Song Tranh 2 reservoir, Vietnam

Reservoir-triggered seismicity (RTS) has the potential to generate disastrous seismic events of M6 and bigger. Song Tranh 2 (STR2) is an artificial water reservoir located in Central Vietnam. High seismic activity has been observed in this area since the reservoir was first filled in 2011. The relation between water level and seismic activity in the Song Tranh area is complex, and previous studies have led to the conclusion that ongoing STR2 seismic activity is an example of the delayed response type of RTS. However, the first phase of the activity observed after impoundment has been deemed a rapid response type. There were three stages of the reservoir filling periods: first, a period of initial impoundment, hereinafter referred to as pre-gap period (from 05/01/2011 to 10/06/2012), then a gap period (from 10/06/2012 to 31/08/2013) where reservoir impoundment stopped and water was drained to minimum exploitation level, and finally, a third post-gap period (from 31/08/2013 to 19/06/2017). In this work, we prove that the gap in the filling of reservoir results to a 2-fold rise of seismicity rate. The re-filling of the reservoir results to a drop of activity rate, roughly equal to the pre-gap period, accompanied by a significant increase of b-value. As a consequence, after the gap, the exceedance probability is significantly lower in comparison to pre-gap and gap periods. We also proved that the seismicity recorded between 2013 and 2016 manifested seasonal trends related to water level changes during wet and dry seasons. The response of activity and its delay with respect to water level changes suggest that the main triggering factor is pore pressure change due to the significant water level changes observed. The findings indicate that water load and related pore pressure changes considerably influence seismic activity and stress orientation in this area.</p

Studying induced seismicity within the EPOS Thematic Core Service on Anthropogenic Hazards (TCS-AH)

The EPOS TCS-AH brings together a broad community interested in Anthropogenic Hazards (AH) related to induced seismicity. It is designed as a functional e-research infrastructure that provides access to a large set of relevant data and allows free experimentations in a virtual laboratory, promoting interdisciplinary collaborations between stakeholders (the scientific community, industrial partners and society). The platform provides datasets as Episodes, which comprehensively describe AH cases for infrastructures, people and/or environment. They are grouped in several categories of subsurface exploitations: CO2 sequestration, conventional hydrocarbon extraction, geothermal energy production, reservoir impoundment, unconventional hydrocarbon extraction, underground gas storage, underground mining, and wastewater injection. They gather datasets relevant for the considered hazards (e.g. seismic, air/water quality), industrial data (e.g. well path, injection rates, mining front advance, gas production, water level), and other geodata (e.g. geological section, velocity model, faults, shear wave velocity, bathymetric map). Two local data centers (eNodes: IG-PAS/Poland and CDGP-EOST/France) provide metadata and data to the TCS-AH platform in commonly used standards and formats (e.g. miniSEED, GeoTIFF, and .mat). A registration/authorization is mandatory to access some data covered by restriction imposed by data industry providers or shared data embargoed by running projects. The platform grants access to an application portfolio, designed for the AH area, and addressing: (1) basic services for data integration and handling; (2) services for physical models of stress/strain changes over time and space as driven by geo-resource production; (3) services for analyses of geophysical signals; (4) services to extract the relation between technological operations and observed induced seismic/deformation; (5) services to quantitative probabilistic assessments of anthropogenic seismic hazard - statistical properties of anthropogenic seismic series and their dependence on time-varying anthropogenesis; ground motion prediction equations; stationary and time-dependent probabilistic seismic hazard estimates, related to time-changeable technological factors inducing the seismic process; (6) simulator for multi-hazard/multi-risk assessment in exploration/exploitation of georesources (MERGER) - numerical estimate of the occurrence probability of chains of events or processes impacting the environment

An open data infrastructure for the study of anthropogenic hazards linked to georesource exploitation

Abstract Mining, water-reservoir impoundment, underground gas storage, geothermal energy exploitation and hydrocarbon extraction have the potential to cause rock deformation and earthquakes, which may be hazardous for people, infrastructure and the environment. Restricted access to data constitutes a barrier to assessing and mitigating the associated hazards. Thematic Core Service Anthropogenic Hazards (TCS AH) of the European Plate Observing System (EPOS) provides a novel e-research infrastructure. The core of this infrastructure, the IS-EPOS Platform (tcs.ah-epos.eu) connected to international data storage nodes offers open access to large grouped datasets (here termed episodes), comprising geoscientific and associated data from industrial activity along with a large set of embedded applications for their efficient data processing, analysis and visualization. The novel team-working features of the IS-EPOS Platform facilitate collaborative and interdisciplinary scientific research, public understanding of science, citizen science applications, knowledge dissemination, data-informed policy-making and the teaching of anthropogenic hazards related to georesource exploitation. TCS AH is one of 10 thematic core services forming EPOS, a solid earth science European Research Infrastructure Consortium (ERIC) (www.epos-ip.org)