Structural Position and Parameters of the Paleoearthquakes in the Area of Vottovaara Mountain (Middle Karelia, Eastern Part of the Fennoscandian Shield)

Shvarev, S.V.; Rodkin, M.V.

Авторы: Shvarev S.V., Rodkin M.V.
Журнал: Seismic Instruments
Том: 54
Номер: 2
Год издания: 2018
Первая страница: 199
Последняя страница: 218
DOI: 10.3103/S0747923918020093
Аннотация: Abstract⎯The traces of strong earthquakes in the territory of Fennoscandia have been recorded by many scientistsalready for several decades. The seismogenerating paleostructures, such as postglacial discontinuitiesin the crystalline basement accompanied by a complex of deformations in the loose deposits are found in theterritories of Sweden, Norway, and Finland that border Russia, in which case the spatial correlation of thepostglacial faults and modern seismicity is established. Such structures have not yet been discovered in Russia,though the traces of strong earthquakes in the form of rock deformations and postglacial sediments arefound by different groups of researchers over the whole territory of Eastern Fennoscandia. The obtained datamake it possible to identify the linear zones of concentration of paleoearthquakes (seismic lineaments) thatalso occur in the modern relief and modern seismicity. However, the problem of postglacial seismicityremains a subject for discussions concerning the localization of the foci, their genesis, and regime. A remainingissue is also distinguishing between seismogenic, cryogenic, and glaciodislocations. The important questionsthat need to be solved include parametrization of paleoearthquakes and determination of their nature,structures, age, and magnitude. One of the key segments is the area of Vottovaara Mountain in Middle Karelia,which is a part of the Vottovaara–Girvas seismic lineament, where seismic dislocations were found earlier.For studying this probable paleo-focal zone in detail, remote sensing data, field geological and geomorphologicalobservations, and computational methods for estimating the peak values of paleoearthquake massvelocities are used. The typical zones of development of different types of seismic deformations are revealed.A potential seismogenerating fault related to the northwest-striking Vottovaara–Girvas seismic lineament isfound; its probable shear kinematics is determined from the ratio of pulse displacements of rock blocks ondifferent wings of the fault. The sequence of a few strong events which occurred here in the interglacial andpostglacial periods is identified. The effects of interaction between the seismic activity and the glacial exarationon the formation of the modern image of the focal zone are established. Using alternative approaches toestimating shaking intensity by the macroseismic INQUA scale, the scale by F.F. Aptikayev, and the nomogramby M.V. Rodkin, the intensity of the recent strong Early Holocene seismic event, which occurred hereat 8.9 ka according to A.D. Lukashov, is determined. According to the agreed estimates, the intensity reached9–10 points at a probable magnitude of 7.5–8. This work carried out using a number of new approachesdeveloped by the authors makes it possible to characterize paleoseismicity in more detail.
Добавил в систему: Шварев Сергей Валентинович

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Structural Position and Parameters of the Paleoearthquakes in the Area of Vottovaara Mountain (Middle Karelia, Eastern Part of the Fennoscandian Shield)статья

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