Mapping S-Wave Attenuation Field of the North Tien Shan Region Using Seismogram Coda for Local Earthquakes and Quarry Blasts

Izvestiya, Atmospheric and Oceanic Physics - We have mapped the short-period shear-wave attenuation field in the lithosphere of the North Tien Shan and analyzed seismograms of local earthquakes and...     

Deep Structure and Folded-Block Structure of the Garhwal Himalayas (India): Results of Integrated Geological and Geophysical Study

Geotectonics - The geological and geophysical study of the representative segment of the Alpine-Himalayan mobile belt—the Central zone of the Garhwal Himalaya—was conducted. The results...     

Functional organization of vegetation in the system of cartographic forecasting

Presented are the results from the assessment stage of forecasting-cartographic investigations into the vegetation in the Angara-Lena interfluve. An assessment is made of the main (preferred) and secondary ecological functions of vegetation within the geosystems. We demonstrate their changes with respect to native (reconstructed) vegetation.     

Early Turonian global warming in the Atlantic and Indian Oceans according to the data of the Foraminifera analysis

In the article, my own data on the species composition of the shells of planktonic Foraminifera (PF) from the Early Turonian sediments of the Atlantic and Indian Ocean and from a number of the cross sections of Australia have been analyzed. In addition, literature materials on the epicontinental basins of the northern hemisphere were also studied. The foraminifera species (PF) are grouped, and four types of thanatocoenoses are distinguished according to their relationship. A climatic zonality map for the early Turonian was constructed on the basis of the spatial distribution of these types. The reconstruction obtained was compared with the climatic maps compiled earlier for the later time intervals of the Late Cretaceous. It was established that the Turonian was characterized by the warmest climate. The tendency for global warming was the most clearly manifested in the Early Turonian.     

Activation of seismicity in Central and South Asia after the Makran earthquakes: Possible acceleration of preparation of large seismic events in the Tien Shan region

Two zones of seismicity (ten events with M _w = 7.0–7.7) stretching from Makran and the Eastern Himalaya to the Central and EasternTien Shan, respectively, formed over 11 years after the great Makran earthquake of 1945 (M _w = 8.1). Two large earthquakes (M _w = 7.7) hit theMakran area in 2013. In addition, two zones of seismicity (M ≥ 5.0) occurred 1–2 years after theMakran earthquake in September 24, 2013, stretching in the north-northeastern and north-northwestern directions. Two large Nepal earthquakes struck the southern extremity of the “eastern” zone (April 25, 2015, M _w = 7.8 and May 12, 2015, M _w = 7.3), and the Pamir earthquake (December 7, 2015, M _w = 7.2) occurred near Sarez Lake eastw of the “western” zone. The available data indicate an increase in subhorizontal stresses in the region under study, which should accelerate the possible preparation of a series of large earthquakes, primarily in the area of the Central Tien Shan, between 70° and 79° E, where no large earthquakes (M _w ≥ 7.0) have occurred since 1992.     

Estimating heat flow from an unsteady temperature log of submarine borehole BDP-98 (Lake Baikal)

We have applied the method of one temperature log suggested by Kutasov in 1987 to process an unsteady temperature log of the 674 m deep submarine borehole BDP-98-2 (Akademichesky Ridge, Lake Baikal) and found it suitable to reconstruct the primary steady thermal gradient not disturbed by drilling. The steady gradient we derived using a special formalism, with reference to drilling conditions and measured thermal properties of sediments, was 63 mK/m, more than two times the unsteady gradient at different depths. Heat flow calculated with this gradient and a mean thermal conductivity of 1.1 W/(m·K) was 70 mW/m², which is consistent with earlier geothermal data from the same area. Thus, the one-log procedure is a useful tool to predict the original undisturbed thermal gradients and estimate approximate heat flows if a single unsteady temperature log is available.     

Annular seismicity structures and the March 11, 2011, earthquake (Mw = 9.0) in Northeast Japan

The characteristics of seismicity prior to the series of eight very strong earthquakes (M _w = 7.0–9.0) in Northeast Japan are discussed. Ring seismicity structures that appeared prior to all eight events in two depth ranges of 0–33 and 34–70 km are identified. The epicenters of the main shocks were located near areas of crossing or touching of shallow and deep rings. It was shown that the sizes of shallow rings and threshold magnitudes corresponding to seismicity rings grow with the energy of the main shocks. It was noted that the prognosis with respect to the place and magnitude of the catastrophic earthquake on March 11, 2011, had been made before it based on the data obtained prior to July 1, 2009. Use of the new data obtained prior to March 10, 2011, enabled us to specify this prognosis significantly. We obtained correlation dependences of threshold magnitudes on the energy of the main shocks (with a high correlation coefficients). It was shown that the duration of the period for seismicity rings to emerge in the considered region nearly did not depend on magnitude. The nature of annular structures and the possibility of application of their parameters for prognosis of strong earthquakes were discussed.     

The results of gravity surveys at geophysical grounds in the Kaluga region

The scientific educational practice on gravimetry for the second-year students of the geophysical specialty in 2012–2013 was executed in Central Russia (Kaluga region, the Village of Aleksandrovka). It allowed us to provide an educational process with modern high-precision gravimeters and to fully preserve the curricula and to add elements of topography and geodesic practice. Over these 2 years reliable facts and data were received, which illustrated the possibilities of high-precision gravity measurements in studying the sedimentary cover features of a geological structure.