Seismic instruments: article

Аnnotation: The study of stresses and deformations in aseismic areas is difficult due to the lack of strong seismic events. In suchcircumstances, every earthquake, even relatively weak, is of high importance. All information on tectonic stresses and their dynamics, e.g . information on origin time, location and magnitude of aftershocks, has to be retrieved from available seismic data. The earthquake near the town of Mariupol occurred on August 7, 2016 and, according to various seismological centers, had body wave magnitude between 4.5 and 4.9. We found12 aftershocks within 5 days after the main shock using two seismic arrays (AKASGиBRTR) and one three-component station (KBZ) of the International Monitoring Systemas well as two seismic arrays of the Institute of Geospheres Dynamics, Russian Academy of Sciences. For six aftershocks, signals were found atthreeand more stations. Other six aftershocks were detected at two from threeclosest stations. Signal detection, association of seismic arrivals with the aftershocks of the main shock as well as estimation of magnitude and relative location of the aftershocks were carried out using the method of waveform cross-correlation (WCC). Only the signals from the main shock were used as waveform templates in the WCC method. In order to improve signal-to-noise ratio and the accuracy of onset time estimates for regular seismic phases we used waveform templates of different length - from 10 s to 180 s depending on wave type and event-station distance and filtering in narrow frequency bands. The highest detector sensitivity and accuracy of the P -wave onset time estimates can be reached when the whole signal, from P to L