Category: Events

Use of mathematical methods, sometimes even quite elementary, in other areas of knowledge often proves to be very efficient. As an example of such use, and, at the same time, an example of cooperation between IEPT RAS and OGRI RAS (Oil and Gas Research Institute RAS), we can point out the results of correlation analysis of the content of trace elements (TE) in oils, coals, black and oil shales, as well as in oil degradation products with the average chemical composition of the upper, middle and lower continental crust and biota.

The goal of the study is to identify the possible locations of strong M6+ earthquakes in the Altai-Sayan-Baikal region.

New publication titled “Unified Scaling Law for Earthquakes: Space-Time Dependent Assessment in Friuli-Venezia Giulia Region” by Anastasia Nekrasova (IEPT RAS) and Antonella Peresan (National Institute of Oceanography and Experimental Geophysics (OGS), Italy) in “Frontiers in Earth Science” (JRL Q2).

The scientists from the Netherlands, Russia, and Romania estimate earthquake source parameters in Vrancea seismic zone and surrounding regions between 2014 and 2020, and determine the stress field via focal mechanism inversion and unsupervised machine learning. The work was published in Tectonophysics (Q1, JIF=3.048).

Major earthquakes of M ≥7 are complex. Seismic energy accumulation, release, and redistribution in the lithosphere are not yet well studied. The geometry, timing, and slip distribution of the complex nonlinear system of the lithospheric blocks-and-faults involved is usually not well resolved.

During last decades, the question of the effect of ocean tides on seismicity has been widely investigated. The issue of whether tidal forces really affect seismicity has been raised many times in the literature.

In the present study the differential probability gain approach (Shebalin et al., 2012; Shebalin et al., 2014) is used to estimate quantitatively the change in aftershock rate at various levels of ocean tides, relative to an average Omori-Utsu model that supposes no dependence on tides. The differential probability gain function is a numeric factor indicating how much the rate of aftershocks is increased or decreased on average at specific values of the tide heights.

Man-made seismicity is a response of the brittle crust to fluid injection at depth and to the subsequent increase in pore-pressure and stress field perturbations. In Oklahoma, where the sharp increase in earthquake rate correlates with injection operations, we show that the earthquake-size distribution can differ significantly on the volume of injected fluid. The size distribution of M<3.5 earthquakes exhibits a near-constant slope b, while significant variation of b-values (from b≈1to b>2) may be documented for larger magnitude ranges. This change shows statistically significant positive dependence on injection activity. In addition, largest events occur at the border of the injection area at some distance from massive injection, and in the periods of steady injection rate. These observations suggest that a deficit of large induced earthquakes under conditions of high injection rate can be accompanied by an overall increase of natural seismicity along pre-existing faults in the surrounding volume, where large events are more likely to be triggered over longer space-time scales.

More“Condition of occurrence of large man-made earthquakes in the zone of oil production, Oklahoma”