Small-aperture-array translational and rotational seismograms from distant sources - An example of the Jan Mayen Mw 6.8 of 30 August 2012 earthquake

0467005 - ÚSMH 2017 RIV NL eng J - Journal Article
Brokešová, J. - Málek, Jiří
Small-aperture-array translational and rotational seismograms from distant sources - An example of the Jan Mayen Mw 6.8 of 30 August 2012 earthquake.
Physics of the Earth and Planetary Interiors. Roč. 256, JUL (2016), s. 1-12. ISSN 0031-9201. E-ISSN 1872-7395
R&D Projects: GA ČR GA15-02363S
Institutional support: RVO:67985891
Keywords : seismic rotation * true backazimuth * apparent seismic phase velocity * Rayleigh-wave dispersion
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 2.075, year: 2016

We present the seismic rotation rate due to the earthquake of Mw 6.7 at the Jan Mayen island, obtained from broad-band seismograms at a distance of about 2740 km. The order of magnitude of the rotation rate amplitude is only 10-9 rad/s in this case. It is studied with a focus on rotation-to-translation relations. A joint analysis of the rotational and translational data allowed us to determine the true backazimuth and phase velocity of S- and Rayleigh waves. For the surface waves, we studied the frequency dependence of both the backazimuth and phase velocity (wave dispersion). The results are independently confirmed by a method based on time delays between translational records within a small-aperture array. Both methods revealed an unusual velocity drop in the dispersion curve between the periods of 18 and 22 s. This feature may be an indication of a low-velocity zone in the lower crust.
Permanent Link: http://hdl.handle.net/11104/0265172