Bull Volcanol (1998) 59:490–505 Q Springer-Verlag 1998 ORIGINAL PAPER V. V. Ponomareva 7 M. M. Pevzner 7 I. V. Melekestsev Large debris avalanches and associated eruptions in the Holocene eruptive history of Shiveluch Volcano, Kamchatka, Russia Received: 18 August 1997 / Accepted: 19 December 1997 Abstract Shiveluch Volcano, located in the Central Key words Volcanic debris avalanches 7 Repetitive Kamchatka Depression, has experienced multiple flank flank failures 7 Shiveluch Volcano 7 failures during its lifetime, most recently in 1964. The Tephrochronology 7 Radiocarbon dating 7 Kamchatka 7 overlapping deposits of at least 13 large Holocene de- Russia bris avalanches cover an area of approximately 200 km2 of the southern sector of the volcano. Deposits of two debris avalanches associated with flank extrusive Introduction domes are, in addition, located on its western slope. The maximum travel distance of individual Holocene Slope failure of a volcanic edifice can produce a volu- avalanches exceeds 20 km, and their volumes reach minous and extremely mobile debris avalanche that F3km3. The deposits of most avalanches typically travels beyond the volcano at high velocity (Siebert have a hummocky surface, are poorly sorted and 1984, 1996). Such avalanches can thus be hazardous and graded, and contain angular heterogeneous rock frag- sometimes occur without distinct precursors on both ments of various sizes surrounded by coarse to fine ma- active and extinct volcanoes (Siebert 1996; Melekestsev trix. The deposits differ in color, indicating different and Braitseva 1984). Therefore, volcanoes that re- sources on the edifice. Tephrochronological and radio- peatedly produced avalanches are of particular interest carbon dating of the avalanches shows that the first (Palmer et al. 1991; Beget and Kienle 1992; Moore et large Holocene avalanches were emplaced approxi- al. 1994). In Kamchatka several volcanoes, including mately 4530–4350 BC. From F2490 BC at least 13 aval- Shiveluch, Bezymianny, Kamenb, Taunshits, Bakening, anches occurred after intervals of 30–900 years. Six and Mutnovskii, have experienced large sector-collapse large avalanches were emplaced between 120 and 970 events (Melekestsev and Braitseva 1984; Melekestsev AD, with recurrence intervals of 30–340 years. All the at al. 1990; Belousov 1995; Melekestsev and Dirksen debris avalanches were followed by eruptions that pro- 1997). But only Shiveluch, famous for its 1964 flank duced various types of pyroclastic deposits. Features of failure followed by an eruption (Gorshkov and Dubik some surge deposits suggest that they might have origi- 1970; Belousov 1995), experienced multiple debris aval- nated as a result of directed blasts triggered by rocks- anches during its lifetime (Belousova and Belousov lides. Most avalanche deposits are composed of fresh 1994; Ponomareva and Pevzner 1994, 1995). andesitic rocks of extrusive domes, so the avalanches Documenting and dating Holocene debris aval- might have resulted from the high magma supply rate anches is part of our ongoing study of the Shiveluch and the repetitive formation of the domes. No trace of eruptive history (Melekestsev et al. 1991; Ponomareva the 1854 summit failure mentioned in historical records and Pevzner 1996; Pevzner et al. 1998). Detailed geo- has been found beyond 8 km from the crater; perhaps logical and tephrochronological studies, which started witnesses exaggerated or misinterpreted the events. in 1978, allow us to identify and date these debris aval- anches and study the juvenile deposits of associated Editorial responsibility: D. A. Swanson eruptions. This paper presents a detailed account of the large prehistoric Holocene debris avalanches and Vera V. Ponomareva (Y) 7 Ivan V. Melekestsev Institute of Volcanic Geology and Geochemistry, Piip Blvd., 9, landslides, including their stratigraphic positions, ages, Petropavlovsk-Kamchatsky, 683006 Russia areas, travel distances, and other parameters. The inter- e-mail: ivgg6svyaz.kamchatka.su pretation of new air photos, and our ongoing field Maria M. Pevzner work, allow us to study in detail the topography and Geological Institute, Pyzhevsky per., 7, Moscow, 109017 Russia stratigraphy of the 1964 deposits and to suggest a new 491 interpretation of the formation of the 1964 debris aval- Written records of the Shiveluch activity date back anche that could to some extent be applied to older av- to 1739 and report on the eruptions in 1739, 1790 alanches as well. (1793), and between 1790 and 1810, but this informa- tion lacks certainty (Gorshkov and Dubik 1970). More reliable records begin in 1854 when a large eruption ac- General description and historical eruptions of companied by voluminous ashfall and failure of the Shiveluch summit was recorded (Ditmar 1890), although our stud- ies show that this description is not precise. The next Shiveluch Volcano (Fig. 1), situated in the Central eruption (formation of a dome and its subsequent de- Kamchatka Depression in the supposed conjunction struction accompanied by pyroclastic flows) occurred in zone of the Aleutian and Kuril-Kamchatka island arcs 1879–1883. Later eruptions took place in 1897–1898, (Fig. 2), is considered to be the northernmost active 1905, 1928–1929, and 1944–1950, and resulted in several volcano of Kamchatka. It is one of the most prolific ex- extrusive domes and minor ashfalls (Gorshkov and Du- plosive centers of Kamchatka, with a magma discharge bik 1970; Meniailov 1955). of approximately 36!106 tons per year, an order of A large plinian eruption of Shiveluch occurred in magnitude higher than that typical of island arc volca- 1964. It began with the formation of a large debris aval- noes (Melekestsev et al. 1991). Shiveluch is a composite anche deposit (Figs. 1, 3), first interpreted to be the re- volcanic edifice. Late Pleistocene Old Shiveluch strato- sult of a directed blast (Gorshkov and Dubik 1970; Bo- volcano was partly destroyed by a large eruption that goyavlenskaya et al. 1985; Melekestsev et al. 1991) and formed a caldera 9 km across. Young Shiveluch erup- later reinterpreted as the result of a sector collapse tive center is nested in the caldera (Fig. 1). The present (Belousov 1995). The area covered by the 1964 debris altitude of Old Shiveluch is 3283 m, and the summit of avalanche deposit is approximately 98 km2, its volume the active Young Shiveluch is approximately was estimated at approximately 1.5 km3 (Gorshkov and 2800 m a.s.l. The maximum height of the edifice above Dubik 1970), and its travel distance approximately its surroundings is more than 3200 m. 16 km (Belousov 1995). The debris avalanche deposits Young Shiveluch is composed of multiple coalesced resemble those of Mount St. Helens (Bogoyavlenskaya extrusive domes, surrounded by agglomerate mantles et al. 1985; Belousov 1995). Failure of the edifice trig- and short but thick (up to 100 m at the front) lava gered a minor phreatic explosion (0.01 km3 of ash; Bel- flows. Its activity during the Holocene has been charac- ousov 1995) followed by a powerful plinian eruption terized by plinian eruptions alternating with periods of that produced tephra fall and pyroclastic flow deposits dome growth. Several extrusive domes were emplaced with a total volume of 0.6–0.8 km3 (Gorshkov and Du- at the volcano’s foot, including the Late Pleistocene bik 1970). The eruption formed the present-day crater. Semkorok domes at the southeastern base and the Ho- An extrusive dome has been growing in the crater since locene Karan domes at the western slope of Old Shive- 1980, occasionally producing small block-and-ash flows, luch (Fig. 1). The products of Young Shiveluch are landslides, and minor ashfalls (Dvigalo 1984; Gorelchik dominantly magnesian andesite (Melekestsev et al. et al. 1995; Khubunaya et al. 1995; Zharinov et al. 1991). 1995). Fig. 1 Shiveluch Volcano viewed from the south. Erup- tive centers: O Old Shiveluch; Y Young Shiveluch; K Karan extrusive domes; S Semkorok extrusive domes. River val- leys: B Baidarnaya; Kb Kabe- ku; SI Suhoi Il’chinets. The hummocky deposits of the Late Pleistocene debris aval- anche are seen in the fore- ground, and the deposits of the 1964 debris avalanche are nearer the volcano. (Courtesy of N. P. Smelov) 492 Fig. 3 Map showing the debris avalanche deposits. Mappable av- alanche deposits are shown in various fillings; those observed only in sections are shown by encircled numbers. Arrows show the location of river valleys: 2 Mutny; 3 Karina; 4 Baidarnaya; 4’ Ka- menskaya; 5 Kabeku; 6 Suhoi Il’chinets. The numbers of the de- bris avalanche units and river valleys coincide with those in Fig. 6. Fig. 2 Location map showing eruptive centers, the rims of the See text for explanations. Dashed lines show the supposed bord- Late Pleistocene caldera and the 1964 crater, river valleys men- ers of debris avalanche deposits. A–Ab, B–Bb, and C–C’ are the tioned in the text, and glaciers in the upper streams of some val- lines of the profiles in Fig. 12. SM Agglomerate mantle of Sem- leys. The outline of the 1964 debris avalanche deposits is shown korok extrusive domes south of the volcano. Most of the sections measured in 1978–1997 are shown by dots; those exposing deposits older than the KL ash from Kliuchevskoi Volcano (5800–6000 years BP; Table 1) are shown by crosses in general with Belousov (1995) and believe that this deposit formed as a result of a large rockslide. Older similar deposits likely had the same genesis. The depos- Before the 1964 eruption researchers at Shiveluch its of the prehistoric debris avalanches have similar already had paid attention to peculiar deposits that are characteristics, such as hummocky surface and poor composed of large angular rock fragments supported sorting and grading, with abundant angular to sub- by coarse-grained matrix and exposed in deep valleys at rounded heterogeneous rock fragments of various sizes the southern slope of the volcano. These deposits were in a coarse to fine matrix.