Geophysical Survey

About: Geophysical Survey is a facility organization based out in Obninsk, Russia. It is known for research contribution in the topics: Geology & Fault (geology). The organization has 308 authors who have published 256 publications receiving 3067 citations. The organization is also known as: Federal State Institution of Science Geophysical Survey of the Siberian Branch of the Russian Academy of Sciences.

Anatomy of the Bezymianny volcano merely before an explosive eruption on 20.12.2017.

Abstract: Strong explosive eruptions of volcanoes throw out mixtures of gases and ash from high-pressure underground reservoirs. Investigating these subsurface reservoirs may help to forecast and characterize an eruption. In this study, we compare seismic tomography results with remote sensing and petrology data to identify deep and subaerial manifestations of pre-eruptive processes at Bezymianny volcano in Kamchatka shortly before its violent explosion on December 20, 2017. Based on camera networks we identify precursory rockfalls, and based on satellite radar data we find pre-eruptive summit inflation. Our seismic network recorded the P and S wave data from over 500 local earthquakes used to invert for a 3D seismic velocity distribution beneath Bezymianny illuminating its eruptive state days before the eruption. The derived tomography model, in conjunction with the presence of the high-temperature-stable SiO2 polymorph Tridymite in juvenile rock samples , allowed us to infer the coexistence of magma and gas reservoirs revealed as anomalies of low (1.5) and high (2.0) Vp/Vs ratios, respectively, located at depths of 2–3 km and only 2 km apart. The reservoirs both control the current eruptive activity: while the magma reservoir is responsible for episodic dome growth and lava flow emplacements, the spatially separated gas reservoir may control short but powerful explosive eruptions of Bezymianny.

Upper Crustal Velocity Structure in Slovenia from Rayleigh Wave Dispersion

Abstract: The inversion of surface-wave dispersion curves can provide information on the average elastic properties of the upper crustal layers that are usually poorly sampled by body waves. The broad band digital records of earthquakes which recently occurred in Slovenia and neighbouring regions are used to extract the group velocity of the fundamental mode of Rayleigh waves, using frequency-time analysis (FTAN). The obtained dispersion curves permit a good resolution for the velocity and the thickness of the upper crust. The thickness of the uppermost sedimentary layer varies between 4 and 6 km and its shear-wave velocity is less than 3 km/s. The lower sedimentary layer is 7 to 9 km thick and its shear-wave velocity ranges from about 3.05 km/s in eastern Slovenia, to about 3.25 km/s in western Slovenia. The shear-wave velocity in the crystalline layer is around 3.5–3.7 km/s in the eastern part, while in the western part it reaches a rather high value of about 3.85 km/s.

Ultra-wideband radar waveform calibration for measurements of a heterogeneous material

Abstract: Embodiments of the disclosed technology comprise a ground penetrating radio device and methods of use for obtaining greater resolution. This is achieved by measuring the composition/reflection off a homogeneous material (e.g., metal plate), determining coefficients to correct the measured/reflection in order to make the measurements look like an idealized reference signal, and then using these coefficients in a digital filter to correct measurements/a reflection off a heterogeneous material, such as a road surface. In this manner, the composition of the heterogeneous material is determined with greater accuracy.