Breather-type oscillations of the global tectonic shear stress fields. (November 2020) - Žalohar, Jure
Abstract: In this paper, two observations of the breather-type oscillating tectonic shear stress field in the Earth's crust are described. The normalized tectonic shear stress from the regional earthquake focal mechanisms is calculated by using the modified moment tensor summation method. The results show that the observed time-development of the normalized tectonic shear stress can be modelled as a breather, which is a spatially localized, time-periodic, oscillatory solution of the sine-Gordon equation. It represents the stress and strain fields, which periodically oscillate in time and decay in space as the distance from the center increases. Two case studies are described. The first was observed during the years 2017–2019 in South America, while the second was observed during the years 1977–1979 south of Japan. The first example is an almost ideal breather. The second example contains some natural noise, but can still be modelled as a breather. Highlights: We describe breather-type oscillating tectonic shear stress fields. We use the modified moment tensor summation method. We describe two case studies in South America and in the region of Japan. The two case studies represent two breathers with the opposite phases. Both breathers were stable for one period of time which was about 2 years.