October 30, 2020 (Friday) a strong earthquake M7.0 (seismic moment magnitude) occurred near the coast of Turkey about 100 km from the city of Izmir. Such large seismic energy caused seismic waves to spread all over the planet. They were also recorded by the seismometer network of the University of Silesia. Earthquakes occur every day all over the world, but such a large phenomenon in the Mediterranean basin does not happen often. The cause of such strong seismic events is the continuing collision of the African and Eurasian plates.
The seismic station operating in Sosnowiec is located approximately 1,500 km from the epicenter of the earthquake that occurred in Turkey. The time of the fastest longitudinal wave required to reach the foundations of the Faculty of Natural Sciences was 3 minutes and 15 seconds indicating that the fastest waves propagated at around 7.70 km/s. An angular epicenter distance greater than 10o and the fastest wave velocity suggest that the wave reflected from the Moho boundary (Kulhanek, 1990. “Anatomy of seismograms. Elsevier). Were the shaking felt in Sosnowiec? No, the greatest peak ground amplitude was 0.6 mm/s. The entire earthquake as a result of wave dispersion lasted over 20 minutes in Sosnowiec. Mining tremors occurring in the Upper Silesia last a few seconds and their amplitudes are much larger while very distant and strong seismic events may last even more than an hour and a half but their amplitudes are much smaller.
Detailed information about the earthquake in Turkey can be found at:
https://www.emsc.eu/Earthquake/earthquake.php?id=915787#summary
