Adit-based linear strain measurements made with strainmeters 1 to 100 m long allow oscillation processes to be studied in a wide range: from a few tens of hertz to several years. Both seismic waves from earthquakes and long-period oscillatory signals are recorded, related to tectonic processes. The paper describes measurements made with rod and laser strain metering systems in an adit of the Talaya seismic station (coordinates 51.68° N, 103.65° E, Lake Baikal Region). The elastic moduli of rocks were evaluated using strainmeter, microbarograph data, and petrophysical core analysis. The Earth’s integral rheological parameters, through the Earth’s free and tidal oscillations, are calculated. Our findings are in good agreement with modern models of the Earth’s internal structure. The paper describes coseismic and long-term volumetric strain variations induced by large regional earthquakes.

We present results of study of organic matter in the coastal and bottom sediments of the Laptev Sea (Buor-Khaya Gulf). The study has shown the regularities of organic-matter distribution in the shelf zone adjacent to the glacial coast. The coast composed of a glacial rock complex supplies the largest amount of organic material to the sea as compared with other types of the coast. The average content of organic matter in these strata is similar to 2-3%. The bottom sediments of the shallow littoral zone are significantly depleted in organic carbon (0.1-0.3%) as a result of their active rewashing and the transition of finely dispersed material (mainly organic one) toward the deep sea zones. The content of organic carbon in the bottom sediments increases to 1-2% as the sea deepens to 7-10 m at 5-12 km from the coast. There are frequent local anomalies of organic-carbon contents (up to 4-5%) in the deltaic zones of the sea. The highest contents of organic carbon (up to 3%) have been found in the recent marine sediments in the central, relatively deep zones of the bays. (C) 2017, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

The method of the empirical mode decomposition and its application to the analysis of data obtained using a laser strain meter is described. The issues of adaptation of the method to real data are discussed. The method enables identification of a monotone trend and a slow component of deformation process much more efficiently than the conventional techniques. The method shows reliable operation in cleaning of signals from noise and high frequencies.

The authors have designed a multi-purpose multi-channel data recording and transmission system for the laser strainmeters and the related geophysical and seismic equipment intended for service in operating mines.

The environmental changes in the southern part of the Chukchi Sea over the last 2300 years (two warmings during the ~262 BC–630 AD and ~630–1300 periods AD and 1 cooling ~1300–1840 AD) were inferred from changes in the content of diatoms in sediments (per gram), the ratio of dominant species, and the ecological structure of diatom assemblages. The sediment age was determined based on the recent 210 Pb sedimentation rates at the sampling point (0.43 mm/yr) and radiocarbon dating of mollusk shells. The environmental changes in the southern Chukchi Sea that were inferred from the diatom analysis correlate with global climate changes, viz., the warming events of the early (Roman) and the middle (Medieval) Subatlantic and the cooling of the late (Little Ice Age) Subatlantic.

Detailed study of a peat plateau near the southern boundary of the East European permafrost zone has been performed. The botanical and palynological compositions of the peat to the depth of 10 m, its radiocarbon dates (the AMS method), and its physical and chemical characteristics have been determined. The accumulation of peat in this area began about 8300 years ago at the end of the Boreal period. In the middle of the Atlantic period, the rate of peat accumulation reached 1.44 mm/yr. During the warming phase in the Middle Subboreal period, the peat plateau was subjected to active thermal erosion; part of the peat was eroded. The processes of thermal erosion are also active at present and destroy the edges of peat mounds. At the same time, the gradual accumulation of peat on the plateau continues. An increase in the degree of peat mineralization is expected upon the establishment of aerobic conditions against the background degradation of the permafrost. Peat plateaus and large peat mounds have been the sinks of atmospheric carbon for a larger part of their history. In this context, we do not expect their significant negative influence on the climate in the future.

The study of the phenomenon of acoustic field generation in the lumens of microvessels has been continued. The results of comparative experiments on animals and control test objects are presented. The research was made under normal physiological conditions and with artificial suppression of cardiovascular activity. A direct dependence of the frequency of oscillations of microvessel walls on the velocity of the blood flow was established.