<> "The repository administrator has not yet configured an RDF license."^^ . <> . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden)"^^ . "A crucial issue to analyse the induced seismicity for hydraulic fracturing is the detection and location of massive\r\nmicroseismic or acoustic emissions (AE) activity, with robust and sufficiently accurate automatic algorithms.\r\nWaveform stacking and coherence analysis have been tested for local seismic monitoring and mining induced\r\nseismicity improving the classical detection and location methods (e.g. short-term-average/long-term-average and\r\nautomatic picking of the P and S waves first arrivals). These techniques are here applied using a full waveform\r\napproach for a hydraulic fracturing experiment (Nova project 54-14-1) that took place 410 m below surface in the\r\nÄspö Hard Rock Laboratory (Sweden). Continuous waveform recording with a near field network composed by\r\neleven AE sensors are processed. The piezoelectric sensors have their highest sensitive in the frequency range 1\r\nto 100 kHz, but sampling rates were extended to 1 MHz. We present the results obtained during the conventional,\r\ncontinuous water-injection experiment HF2 (Hydraulic Fracture 2). The event detector is based on the stacking\r\nof characteristic functions. It follows a delay-and-stack approach, where the likelihood of the hypocenter location\r\nin a pre-selected seismogenic volume is mapped by assessing the coherence of the P onset times at different\r\nstations. A low detector threshold is chosen, in order not to loose weaker events. This approach also increases\r\nthe number of false detections. Therefore, the dataset has been revised manually, and detected events classified\r\nin terms of true AE events related to the fracturing process, electronic noise related to 50 Hz overtones, long\r\nperiod and other signals. The location of the AE events is further refined using a more accurate waveform stacking\r\nmethod which uses both P and S phases. A 3D grid is generated around the hydraulic fracturing volume and\r\nwe retrieve a multidimensional matrix, whose absolute maximum corresponds to the spatial coordinates of the\r\nseismic event. The relative location accuracy is improved using a master event approach to correct for travel time\r\nperturbations. The master event is selected based on a good signal to noise ratio leading to a robust location with\r\nsmall uncertainties. Relative magnitudes are finally estimated upon the decay of the maximal recorded amplitude\r\nfrom the AE location. The resulting catalogue is composed of more than 4000 AEs. Their hypocenters are spatially\r\nclustered in a planar region, resembling the main fracture plane; its orientation and size are estimated from the\r\nspatial distribution of AEs.\r\n\r\nThis work is funded by the EU H2020 SHEER project. Nova project 54-14-1 was financially supported by\r\nthe GFZ German Research Center for Geosciences (75%), the KIT Karlsruhe Institute of Technology (15%) and\r\nthe Nova Center for University Studies, Research and Development (10%). An additional in-kind contribution of\r\nSKB for using Äspö Hard Rock Laboratory as test site for geothermal research is greatly acknowledged."^^ . "2017-04" . . . . . . . . . . . . . . . . . . . . . . . . "Arno"^^ . "Zang"^^ . "Arno Zang"^^ . . "Torsten"^^ . "Dahm"^^ . "Torsten Dahm"^^ . . "Claus"^^ . "Milkereit"^^ . "Claus Milkereit"^^ . . "Sebastian"^^ . "Heimann"^^ . "Sebastian Heimann"^^ . . "Simone"^^ . "Cesca"^^ . "Simone Cesca"^^ . . "Jose Angel"^^ . "Lopez-Comino"^^ . "Jose Angel Lopez-Comino"^^ . . "Francesco"^^ . "Grigoli"^^ . "Francesco Grigoli"^^ . . "GFZ German Research Centre for Geosciences, Potsdam, Germany"^^ . . . "GFZ German Research Centre for Geosciences, Potsdam, Germany"^^ . . . "GFZ German Research Centre for Geosciences, Potsdam, Germany"^^ . . . "ETH Zurich, Swiss Seismological Service, Switzerland"^^ . . . "GFZ German Research Centre for Geosciences, Potsdam, Germany"^^ . . . "GFZ German Research Centre for Geosciences, Potsdam, Germany"^^ . . . "GFZ German Research Centre for Geosciences, Potsdam, Germany"^^ . . . . . "EGU General Assembly 2017"^^ . . . . . "Vienna, Austria"^^ . . . . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden) (Image)"^^ . . . . . "Poster_ASPO_EGU2017.pdf"^^ . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden) (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden) (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden) (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden) (Other)"^^ . . . . . . "small.jpg"^^ . . . "Full waveform approach for the automatic detection and location of\r\nacoustic emissions from hydraulic fracturing at Äspö (Sweden) (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #1991 \n\nFull waveform approach for the automatic detection and location of \nacoustic emissions from hydraulic fracturing at Äspö (Sweden)\n\n" . "text/html" . . . "Source parameter estimation" . . . "Sweden" . . . "Unconventional hydrocarbon extraction" . .