ALBERT

Description: The dataset presented here is an earthquake catalog for the Central Sea of Marmara (Turkey) obtained by applying a matched-fliter technic to continuous waveforms. The magnitude of completeness of this catalog is Mc=1.1. We use as templates events published by national agencies (KOERI and AFAD). The matched-fliter technic is described in Bentz et al. (2020). The column of the data file are: event ID, Year, Month, Day, Hour, Minute, Seconds, Matlab time (serial time), Latitude (dec.degrees), Longitude (dec.degrees), Depth (km), Magnitude, Cross-correlation coefficient (CC), Template ID, MAD(ratio between CC and median absolution of daily correlogram), Quality flag The ZIP files contains configuration files for ph2dt and HypoDD applications together with input phase and seismic network data.

Description: Earthquakes associated with fluid injection in various geo-energy settings, such as shale gas and deep geothermal energy, have shelved many projects with great potential. However, the injection-rate dependence of earthquake nucleation length, i.e., the slowly slipping (creeping) fault length in preparation for a subsequent earthquake (Kaneko & Lapusta, 2008), remains elusive. In this study, we take a step towards this issue by performing fluid injection experiments on low-permeability granite samples containing a critically stressed sawcut fault at different local injection rates (0.2 mL/min and 0.8 mL/min) and confining pressures (31 MPa and 61 MPa) (c. f., Ji & Wu, 2017; Wang et al., 2020). An array of local strain gauges and acoustic emission (AE) hypocenter locations were used to monitor the precursory slip of critically stressed faults before injection-induced stick-slip failure (c. f., Passelègue et al., 2020; Wang et al., 2020). The nucleation length was determined for each injection-induced stick-slip event, and its dependence on effective normal stress and injection rate was explored. Herein, we compile the processed data obtained from the experiments in four Excel worksheets. The full description of the methods is provided in Ji et al. (2022).

Description: The dataset presented here is an earthquake catalog for the central Sea of Marmara (Turkey) obtained by applying a traditional STA/LTA technique to the continuous waveforms. The magnitude of completeness of this catalog is MW = 1.4. The full description of the data processing and creation of the catalog is provided in the paper “Near - fault monitoring reveals combined seismic and slow activation of a fault branch within the Istanbul-Marmara seismic gap in NW Turkey” published by Martínez-Garzón et al., in Seismological Research Letters. The data are provided as the following two ASCII tables: The file 2021-004_Martinez-Garcon-et-al_Initial_seismicity_catalog contains the seismic events for which we could successfully calculate an earthquake location. The ASCII table has the following columns: columns: id, year, month, day, hour, minute, second, serial time, latitude, longitude, depth [km], magnitude, horizontal error [km], vertical error [km], RMS, maximum azimuthal gap [degree]. The table 2021-004_Martinez-Garcon-et-al_Relocated_seismicity_catalog contains the seismic events for which we could refine the initial location and obtain a double-difference refined location. The ASCII table has the following columns: id, latitude, longitude, depth [km], horizontal error [km], vertical error [km].

Description: This data publication contains seismic catalog developed by the analysis of seismicity recorded during hydraulic stimulation campaign performed in May 2020 in the 5.8-km deep OTN-2 well near Helsinki, Finland as part of the St1 Deep Heat project (Kwiatek et al., 2022). The original seismic data to develop the seismic catalog were acquired with the high-resolution seismic network composed of 22 geophones surrounding the project site. The centerpiece of the network was a 10-level borehole array of Geospace OMNI-2400 geophones (3C/15 Hz) sampled at 2 kHz placed in the OTN-3 well adjacent to the OTN-2 injection well, and located at 1.93 - 2.55 km depth, approx. 3km from injection intervals. Additional 12 stations at distances 〈10 km from project site formed the satellite network that was equipped with short-period 3C 4.5 Hz Sunfull PSH geophones, completing the seismic network. Near-real-time processing of induced seismicity data started on Jan 26, 2020, i.e. about 3 months prior to the onset of the injection, covering entire period of the stimulation campaign in May 2020. The monitoring stopped end of June 2020, about one month after the stimulation finished. The monitoring campaign resulted in initial industrial seismicity catalog containing 6,243 events that was refined and further extended (cf. Kwiatek et al., 2022). The final catalog associated with this data publication contains 6,318 earthquakes, including 197, 5427 and 694 events recorded before, during, and after stimulation campaign. The core catalog data contains origin time, local magnitude, (re)location and focal mechanism data.

Description: To understand the physical mechanisms governing fluid-induced seismicity at field-scale fluid injection projects, we conducted fluid-induced fault slip experiments in the laboratory on critically stressed saw-cut sandstone samples with high permeability using different fluid pressurization rates. The data archived here acts as supplementary material to Wang et al. (2020; https://doi.org/10.1029/2019GL086627). Experiments were conducted at room temperature using a servo-hydraulic tri-axial deformation apparatus (MTS) equipped with a pore pressure system (Quizix pumps) at Experimental Rock Deformation Laboratory, GFZ. To investigate the correlation between fault slip and fluid pressure, we applied two different fluid injection schemes (hereafter tests “SC1” and “SC2”, respectively). ‘TestSC1’ refers to the fluid-induced fault slip experiment performed at fluid pressurization rate of 2 MPa/min while ‘TestSC2’ indicates the fluid-induced fault slip experiment performed at fluid pressurization rate of 0.5 MPa/min. The other boundary conditions for both experiments are similar. In addition, to simultaneously record acoustic emission (AE) events induced by artificial fault slip, 16 piezoelectric transducers (PZTs, resonance frequency ~1 MHz) contained in brass cases were directly mounted to the surface of samples, ensuring full azimuthal coverage for AE events. AE waveforms were amplified first by 40 dB using preamplifiers equipped with 100‐kHz high‐pass filters and then recorded at a sampling rate of 10 MHz with 16‐bit amplitude resolution. Each experiment lasted for about 4 hours. Throughout the experiment, mechanical data (measured by MTS) and hydraulic data (measured by Quizix pump) were all synchronously monitored with a sampling rate of 10 Hz whereas acoustic emission data were recorded with a sampling rate of 10 MHz. All results shown are recorded as a function of experimental time. The data are provided in tab-separated ASCII-Format (.txt). 2020-002_Wang-et-al_TestSC1.zip and 2020-002_Wang-et-al_TestSC2.zip are composed of 7 txt files and 8 txt files, respectively, as described below in Table 1. The first column represents time in second and the subsequent columns are indicated by the corresponding header at the first row. The second row indicates the unit for each column data. The raw data was processed with MATLAB. The algorithms we implemented include the moving average method, statistical regression and our developed MATLAB-based codes.

Description: The dataset is supplementary material to the Solid Earth research article of Leonhardt et al. (2021). The dataset is a high-resolution catalog of seismicity framing the stimulation campaign of a 6.1 km deep Enhanced Geothermal System (EGS) in Helsinki suburban area, Finland. Within the St1 Deep Heat project, a total of 18,160 m3 of fresh water was injected into crystalline rocks during 49 days in summer 2018. The seismicity was monitored by a 12-level seismometer array at 〉2km depth and a seismic network of near-surface borehole sensors surrounding the EGS site. We expanded and refined the original catalog of Kwiatek et al. (2019) including detected seismic events and earthquakes that occurred two month after the end of injection and determining new locations and relocations on the basis of a new velocity model derived from a post-stimulation vertical seismic profiling campaign. A detailed description of the catalog reprocessing as well as a description of basic statistical and spatio-temporal properties of the catalog can be find in the data description file. Definition of columns in the data table (also in the header of the data): event ID, event class, datenumber [integer part = day since year 0], year, month, day, hour, minute, seconds, local magnitude MLHEL, moment magnitude MW, absolute location in local cartesian coordinates [easting (m), northing (m), altitude (m)], relocated location in local cartesian coordinates [easting (m), northing (m), altitude (m)], fault plane solutions of estimated focal mechnisms [strike (°), dip (°), rake(°)] and root mean square fault plane uncertainty of estimated focal mechanisms.