This dataset contains the estimated source parameters using both Spectral Fitting (SF) method and Generalized Inversion Technique (GIT) for 1,577 earthquakes with magnitude ML1.0-5.7 during the time span 2006-2020 in the Sea of Marmara region. The study area surrounds the Sea of Marmara, close to the megacity Istanbul, with longitudes ranging from 27.3° to 29.35° and latitudes ranging from 40.5° to 40.9°. Source parameters including seismic moment (M_0^SF), corner frequency (f_c^SF), quality factor (Q^SF), and Brune stress drop (∆σ^SF), are estimated and calculated using SF approach (Kwiatek et al., 2011, 2014, 2015) with the Simplex method applied in the optimization process (Nelder & Mead, 1965); source parameters from GIT approach including seismic moment (M_0^GIT), corner frequency (f_c^GIT), and Brune stress drop (∆σ^GIT) are also calculated for the same events. The event information, i.e., event date, original time, event longitude, latitude, depth, local magnitude, is obtained from the seismicity catalog of Becker et al. (2023).
These data are supplementary to the GJI research article of Blanke et al. 2020, in which static stress drop estimates of laboratory acoustic emission (AE) waveform records were analyzed. Stick-slip experiments were conducted on two triaxial loaded Westerly Granite samples of different roughness: 1) a smooth saw-cut fault (sample S12) and 2) a rough fault (sample W5). Both experiments resulted in six stick-slip failures of which five were analyzed for each fault. A variant of the spectral ratio technique was applied to find the best fitting source parameters.
Laboratory Experiments:
Acoustic emission waveform data of two triaxial stick-slip experiments was recorded at room temperature on cylindrical oven-dried Westerly Granite samples of 105-107 mm height and 40-50 mm diameter. The experiments were conducted on a smooth saw-cut (sample S12) and a rough fault (sample W5). Both experiments were performed in a servo-controlled MTS loading frame equipped with a pressure vessel. The acoustic emission activity was monitored by 16 piezoceramic transducers with a resonance frequency of about 2 MHz. A transient recording system (DAX-Box, Prökel, Germany) recorded full waveform data in triggered mode at a sampling frequency of 10 MHz and an amplitude resolution of 16 bits. The rough fault W5 was first prepared with Teflon-filled saw-cut notches at 30° inclination to the vertical axis and then fractured at 75 MPa. Then, each sample, S12 and W5, was subjected to constant confining pressure of 133 MPa and 150 MPa and then loaded in axial compression using a strain rate of 3*10-4 mm/s and 3*10-6 mm/s, respectively.
Data description:
The tables 2020-008_Blanke-et-al_S1_S12.txt and 2020-008_Blanke-et-al_S2_W5.txt contain AE locations and occurrence, and source parameter estimates of the smooth fault S12 and the rough fault W5, respectively. Both column headers show coordinates of AE locations (X, Y, Z [mm]), temporal occurrence (t [sec]), seismic moment (M0 [Nm]), corner frequency (f0 [Hz]), source radius (r [mm]), static stress drop (stress drop [MPa]), and moment magnitude (MW). M0 and f0 were estimated from the amplitude spectra, using the spectral ratio technique. The source radii were calculated for S-waves using the dynamic circular source model of Madariaga (1976). Static stress drops were estimated following Eshelby (1957). Both tables are used and displayed in Blanke et al. (2020).