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Seasonal periodicity of the focal mechanisms and the num8er of weak earthquakes in the garm regionстатья
Информация о цитировании статьи получена из
Web of Science
Дата последнего поиска статьи во внешних источниках: 16 января 2019 г.
- Авторы: Lukk A.A., Yunga S.L.
- Журнал: Doklady Akademii nauk SSSR
- Том: 246
- Номер: 1
- Год издания: 1979
- Издательство: Akademiia Nauk Sssr
- Местоположение издательства: Russian Federation
- Первая страница: 44
- Последняя страница: 47
- Аннотация: The existence of certain seasonal periodicity of earthquakes with M>5.5 in various parts of the globe and on the earth as a whole has already been re ported [1-5]. The most comprehensive analysis of this phenomenon was presented by Kropotkin and Lyustikh [5]. They represented the seasonal variation of the earthquake frequency about the monthly average by sinusoidal curve with an amplitude A=10 percent and a maximum and minimum, in respectively, the middle of June and the middle of December. This periodicity is produced by the annual variation in the active gravitational mass of the earth [1, 4, 5], that is, the quantity yM, where у is the gravitational constant, which in general is a function of the earth's velocity in a cosmological coordinate system [1], and M is the mass of the earth*). In this study we will analyze the possibility that in the Garm region there may exist a similar periodicity in the number of weak earthquakes with M = 1 to 4, as well as in their focal mechanism. A study of the focal mechanisms of 2500 weak arthquakes, recorded between 1964 and 1977, revealed that in the Garm region there are several uniformly deformed zones that differ in their stresses and faulting. To reveal these areas, we used our previously published method [7-9]. The largest structural unit was found in the central part of the region, that is, under the Peter I Range (Fig.1). The dominant stress in that zone is uniaxial subhorizontal compression with a 135° azimuth. We also evaluated the mean tensor characteristics of the stressed state of this zone for various overlapping time intervals. For this purpose, we used equally accurate moving-average samples of 100 mechanisms, with an interval equal to half the sample. We found that the variation of the azimuth of the axis of the compressive stress was less than 5°, and the Lode-Nadai coefficient remained positive.
- Добавил в систему: Лукк Альберт Артурович