Original scientific paper

Compression of the Earth's Crust Two Days before Earthquake 22 March 2020 in Zagreb

Nikola Solarić ; Faculty of Geodesy, University of Zagreb, Zagreb, Croatia
Miljenko Solarić ; Faculty of Geodesy, University of Zagreb, Zagreb, Croatia

Abstract

In the first chapter, a brief overview of the earthquakes that occurred in Zagreb and its surroundings in the past was given, as well as these last of magnitudes 5.4 and 5.0 that destroyed Zagreb on 22. 3. 2020. They have caused major damage to more than 25,000 buildings. These earthquakes occurred after 140 years since the great earthquake, which devastated Zagreb in 1880. The epicenters of the 22. 3. 2020 earthquakes were nearby where the epicenter of Zagreb's great earthquake of 1880 was located. However, between 1880 and 2020 there were several more earthquakes that were not as devastating as this one in 1880, but still larger than these last two. By analyzing 24-hour GNSS measurements of GNSS reference points of the Croatian Positioning System (CROPOS) according to our method of differences of daily distances between stations. It was proved that two days before these earthquakes there were a shortening of the distance between the reference GNSS points. In other words, there was compression in the Earth's crust. This compression has already been shown in the analysis of GNSS measurements between GNSS points of positional systems in 4 previous earthquakes: at Kraljevo (2010), Drežnica (Senj, 2013), Skopje (2016) and near Zagreb (2018), as well as now at the most recent earthquakes in Zagreb in 2020. Therefore, it is proposed that the data of the CROPOS can be used in geodesy and in seismology. In this purposes it is obliged to organize continuous calculation the coordinates of reference GNSS points by Bernese software on the basis of which compression in Earth’s crust it is possible to calculate. Also with the help of other geophysical measurement and data it is perhaps possible to predict which seismic activity will result in an earthquake. However, for more reliable monitoring results of seismic activity monitoring by the GNSS measurement method, the stability of reference GNSS points that would be set at a distance between them should be examined. These locations should be determined on the basis of geological data and research. In addition, the distances between GNSS points should not be too short.

Keywords

GNSS reference stations; CROPOS; earthquakes; magnitude; compression; Zagreb

Hrčak ID:

254540

URI

https://hrcak.srce.hr/254540

Publication date:

25.3.2021.

Article data in other languages: croatian

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