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.
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].
Preparatory mechanisms accompanying or leading to nucleation of larger earthquakes have been observed at both laboratory and field scale, but the precise conditions favoring extended nucleation processes are still largely unknown. In particular, it remains a matter of debate why earthquakes often occur spontaneously without noticeable precursors as opposed to an extended failure process accompanied by foreshocks. In this study, we have generated new high-resolution seismicity catalogs framing the occurrence of 20 ML > 2.5 earthquakes at The Geysers geothermal field in California.To this end, a seismicity catalog of the 11 days framing each large event was created. We selected 20 sequences in total from different tectonic settings within the field that sample the entire reservoir depth range and temporal periods with high or low injection rates.Seismic activity and magnitude frequency distributions displayed by the different earthquake sequences are correlated with their location within the reservoir. Sequences located in the northwestern part of the reservoir show overall increased seismic activity and low b-values, while the southeastern part is dominated by decreased seismic activity and higher b-values. Periods of high injection coincide with high b-values, and vice versa. These observations potentially reflect differential stresses and damage varying across the field. About 50 % of analyzed sequences exhibit no change in seismicity rate in response to the large main event. Instead, we find complex waveforms at the onset of the main earthquake, suggesting that small ruptures spontaneously grow into or trigger larger events.