V. A. Shirokov

Publications (3)2.2 Total impact

• Source

  Available from: earth-prints.org

  Article: The nexus of soil radon and hydrogen dynamics and seismicity of the northern flank of the Kuril-Kamchatka subduction zone

  P. P. Firstov, V. S. Yakovleva, V. A. Shirokov, O. P. Malysheva
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  ABSTRACT: The comparison of kinematics and dynamic parameters of radon and molecular hydrogen concentration in subsoil air on the stations network at the Petropavlovsk-Kamchatsky geodynamic proving ground with seismicity of the northern flank of the Kuril-Kamchatka subduction zone was fulfilled in the period from July till August 2004. On the basis of correlation analysis of the regional seismicity and variations of radon flux density calculated using the data of gas-discharge counters of STS-6 type and SSNTDs it was shown that the radon mass transfer abnormal variations are conditioned by both regional seismicity in total and the subduction zone of proving ground. The azimuths of «geodeformation waves» coming to the registration points are calculated during clearly expressed anomaly beginnings, which coincide with directions to earthquake epicenters taking place at the same time. The geochemical anomalies recorded are presumptively deformative by nature and can be conditioned by processes of «quasi-viscous» flow of the lithosphere during rearrangement of tectonic stress fields of the subduction zone. The short-term (predicted time ? <14 days) precursor of the earthquakes swarm was revealed in hydrogen dynamics on August, 4-5 (four earthquakes had M?5.3 and epicentral distance about 130 km from the Paratunka base station).
  Annals of Geophysics. 01/2009;
• Article: Seismic investigation of the roots of the Kliuchevskaya group volcanoes, Kamchatka

  P. P. Firstov, V. A. Shirokov
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  ABSTRACT: Earthquake data from Δ<2° and of indermediate depth of focus in the upper mantle near the Kliuchevskaya volcanic region show a screening effect of longitudinal and transverse waves. The indicated anomalous zones are identified with the region of magma localization. The anomalous zones are at 35–110 km depths.
  Bulletin of Volcanology 02/1971; 35(1):164-172. · 2.20 Impact Factor
• Article: Shiveluch volcano: seismicity, deep structure and forecasting eruptions (kamchatka)

  V.I. Gorelchik, V.A. Shirokov, P.P. Firstov, O.S. Chubarova
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  ABSTRACT: The deep structure, Wadati-Benioff zone (focal zone) geometry and the magma feeding system of Shiveluch volcano are investigated based on 1962–1994 detailed seismic surveillance.A focal zone beneath Shiveluch is dipping at an angle of 70° at depths of 100–200 km. Based on the revealed interrelations between seismicity at depths of 105–120 km and an extrusive phase of its eruptions in 1980 through 1994, it is inferred that primary magmas, periodically feeding the crustal chamber, are melted at depths of at least 100 km. An upsurge of extrusive-explosive activity at the volcano is preceded and accompanied by the increasing number and energy of both volcanic earthquakes beneath the dome and tectonic or volcano-tectonic earthquakes in the zones of NW-striking crustal faults near the volcano.The eruption of April 1993 has been the most powerful since 1964. It was successfully predicted based on interactive use of all seismic data. At the same time the influence of seismicity at depths of 105–120 km under the volcano on the style (and consequently on prediction) of its activity is decisive.
  Journal of Volcanology and Geothermal Research.