One-dimensional velocity models of the earth's crust for determining the parameters of seismic events recorded on the territory of Karelia

Abstract

Introduction or Purpose: The territory of Karelia is located in the southeast of the Fennoscandian shield and has a complex geological structure and is represented by three geoblocks: the Karelian craton, the White Sea mobile belt and the Svecofennian orogen. These areas differ from each other in the geological structure, age and composition of their constituent complexes. The Republic of Karelia is characterized by weak seismicity. During the instrumental period of observations, the magnitudes of seismic events did not exceed 3.2. The choice of a velocity model is an important task in determining the parameters of weak seismic events. Methodology: To study the seismic regime of the region, a seismological network was created, the stations of which are located in different regions of the republic. Seismic stations are equipped with digital broadband equipment that registers various kinds of earthquakes. Seismic data processing is carried out in the ELRESS program. It allows you to determine the time in the source, the error in determining the time of occurrence, the coordinates of the epicenter, the error in determining the epicenter in latitude and longitude and the local magnitude. Results and discussion: The values of the main parameters of seismic events, which are obtained during processing, depend on the used one-dimensional velocity models. The base velocity models are: IASPEI91 and AK-135. The article presents one-dimensional velocity models that are used to determine the coordinates of the hypocenters of seismic events recorded on the territory of Karelia. Conclusion: It is shown that for the northern regions of Karelia it is necessary to use the BARENTS velocity model, for the southwestern regions – the BALTIC velocity model, and for the central regions of Karelia – the KARELIA velocity model.