Eruptive Process, Effects and Deposits of the 1996 and the Ancient Basaltic Phreatomagmatic Eruptions in Karymskoye Lake, Kamchatka, Russia

  1. James D. L. White2 and
  2. Nancy R. Riggs3
  1. A. Belousov and
  2. M. Belousova

Published Online: 24 MAR 2009

DOI: 10.1002/9781444304251.ch3

Volcaniclastic Sedimentation in Lacustrine Settings

Volcaniclastic Sedimentation in Lacustrine Settings

How to Cite

Belousov, A. and Belousova, M. (2001) Eruptive Process, Effects and Deposits of the 1996 and the Ancient Basaltic Phreatomagmatic Eruptions in Karymskoye Lake, Kamchatka, Russia, in Volcaniclastic Sedimentation in Lacustrine Settings (eds J. D. L. White and N. R. Riggs), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304251.ch3

Editor Information

  1. 2

    Department of Geology, University of Otago, PO Box 56, Dunedin, 9015, New Zealand

  2. 3

    Geology Department, Northern Arizona University, Box 4099, Flagstaff, AZ 86011, USA

Author Information

  1. Institute of Volcanic Geology and Geochemistry, Petropavlovsk-Kamchatsky, 683006, Russia

Publication History

  1. Published Online: 24 MAR 2009
  2. Published Print: 18 APR 2001

ISBN Information

Print ISBN: 9780632058471

Online ISBN: 9781444304251

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Keywords:

  • eruptive process, effects and deposits of 1996 and ancient basaltic phreatomagmatic eruptions in Karymskoye lake, Kamchatka, Russia;
  • geographical and geological setting - Kamchatka peninsula;
  • observations of the 1996 eruption;
  • tuff ring morphology;
  • stratigraphy and characteristics of the 1996 pyroclastic deposits;
  • distal base-surge effects and deposits, distal co-surge fallout and ballistic material;
  • effects and deposits of tsunamis and lahars;
  • succession of events and interpretation of the 1996 eruption processes;
  • ascent of magma - vent-clearing explosion(s) - main stage of the eruption: Surtseyan activity;
  • deposits and styles of prehistoric eruptions in the lake

Summary

On 2–3 January 1996 an explosive eruption discharging ≈ 106 kg s−1 of basaltic magma occurred in Karymskoye lake at an initial water depth of ≈ 50 m. Characteristics of the deposits together with analyses of a videotape of several explosions have allowed us to model the eruptive events. Initial vent-clearing phreatic explosions ejected blocks of country rocks (up to 3 m diameter) to distances of up to 1.3 km. Then followed 10–20 h of phreatomagmatic Surtseyan activity (100–200 outbursts of water–gas–pyroclastic mixtures to heights of up to 1 km, with initial velocities of 110 m s−1). The eruption slugs collapsed back into the lake and produced base surges (runout up to 1.3 km; average velocity 12.5 m s−1). The convective eruption plume rose to a height of 3 km and deposited a thin distal fall deposit. The eruption ended with the ejection of scoria-crust bombs (specific basaltic bombs with dense core and scoriaceous crust).

Pyroclasts of the eruption are mostly poorly to moderately vesicular juvenile basaltic particles shaped by a combination of magmatic vesiculation and magma–water interaction. Ninety-five per cent of the products (0.047 km3) formed an underwater tuff ring composed of parallel layers of moderately to poorly sorted lapilli ash and ash lapilli (Md – 3.9 to 0.6ϕ; sorting 1.5–3.2ϕ), each 10–60 cm thick. They were deposited by water-rich base surges that originated from Surtseyan type eruption bursts. The most widespread hazards of the eruption were tsunamis and lahars. At distances < 1.3 km from the crater, base surges and ballistic clasts were very destructive.

Eruptive activity in the lake before 1996 included two eruptions at c. 4800 14C yr BP. The first left deposits similar to those of the 1996 eruption and thus is interpreted as a Surtseyan eruption that occurred at the same water depth as in 1996. The second of the 4800 14C yr BP eruptions deposited extensive cross-laminated base-surge deposits and is interpreted to have occurred in very shallow water.