Report on Tolbachik (Russia) — December 2012
Bulletin of the Global Volcanism Network, vol. 37, no. 12 (December 2012)
Managing Editor: Richard Wunderman.
Tolbachik (Russia) Seismicity precedes onset of dual fissure eruption in November 2012
Please cite this report as:
Global Volcanism Program, 2012. Report on Tolbachik (Russia). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 37:12. Smithsonian Institution.
55.832°N, 160.326°E; summit elev. 3611 m
All times are local (unless otherwise noted)
Nearly 36 years after its last eruption, the largest basaltic eruption in Kamchatka during historic times (1975/76 eruptions; CSLP 51-75; SEAN 01:07, 01:08), Tolbachik (figure 1) began erupting again on 27 November 2012 following almost three weeks of episodic volcanic tremor. The eruption emerged as two fissures along the W side of Tolbachinsky Dol (a lava plateau along the SW flank of Tolbachik), in the same area as the northern vents of the 1975/76 eruptions. The eruption produced both effusive lava flows and explosions that generated low-level ash-bearing plumes.
This report mainly summarizes Kamchatkan Volcanic Eruption Response Team (KVERT) daily and weekly reports and information releases concerning the ongoing (as of early February 2013) Tolbachik fissure eruption.
Seismicity preceding 27 November 2012 eruption. Episodic tremor was recorded at Tolbachik during 7-10, 18, and 26 November 2012; KVERT noted a distinct difference between these episodes of tremor and discrete events that had occurred over "many years" prior. Shallow volcanic earthquakes began on 26 November, increasing in number to ~267 through 27 November. The Aviation Color Code was raised from Green to Yellow (on a scale increasing from Green-Yellow-Orange-Red) on 27 November. In a daily report discussing activity on 27 November, KVERT reported that shallow events, possibly indicating ash explosions, had occurred during 1715-2000. The Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS) reported a strong seismic event at 1752 that day. Informed by KB GS RAS, the Tokyo Volcanic Ash Advisory Center (VAAC) posted a volcanic ash advisory at 1837 (table 1). The ash explosions prompted KVERT to raise the Aviation Color Code to Orange. Continuos tremor occurred for the rest of the day, indicating possible lava flows.
|Date||Time||Plume Altitude (km)||Drift Direction||Remarks (data source)|
|27 Nov 2012||1837||6.1||--||Eruption reported at 1715 (KB GS RAS)|
|27 Nov 2012||2313||10.05||NNW||Eruption (KB GS RAS)|
|29 Nov 2012||1003||3.95||N||VA reported (UHPP)|
|29 Nov 2012||1500||3.65||SE||VA reported (KVERT)|
|29 Nov 2012||1746||3.95||SE||Continuing emissions (satellite imagery)|
|29 Nov 2012||2355||3.95||SE||Continuing emissions (satellite imagery)|
|30 Nov 2012||0600||3.95||N||Continuing emissions (satellite imagery)|
|30 Nov 2012||1152||--||--||VA dissipated on imagery (satellite imagery)|
|30 Nov 2012||1634||NVA reported (UHPP)|
|03 Dec 2012||2138||4.25||NW||VA reported (UHPP)|
|05 Dec 2012||1221||4.25||SE||VA reported (KVERT)|
|07 Dec 2012||1431||4.25||SW||VA reported (KVERT)|
|13 Dec 2012||1139||3.05||NE||VA reported (KVERT)|
|13 Dec 2012||1232||4.55||E||VA reported (UHPP)|
|14 Dec 2012||1209||3.05||NE||VA reported (KVERT)|
|27 Dec 2012||1126||5.2||SE||VA reported (UHPP)|
|07 Jan 2013||1145||3.65||NE||VA reported (KVERT)|
|07 Jan 2013||1202||4.25||NE||VA reported (KVERT)|
Observations reveal two fissure vents. By the early morning of 28 November 2012, observers in Kozyrevsk (~40 km NW) and Lazo (~50 km SW) had reported periodic incandescence from Tolbachik during the night. Later that morning, observers in the same locations reported ash explosions and lava flows in the area of the northern vents of the 1975/76 eruptions, along the W side of Tolbachinsky Dol.
The first available photograph of the eruption showed that lava was issuing through two fissures (figure 2). Ashfall 4-cm-deep was reported in Krasny Yar (~60 km NNW) by midday on 28 November (figure 3). According to a KVERT information release, the Aviation Color Code was raised to Red for a brief period on 29 November, but this was not reflected in the daily reports; the Aviation Color Code remained Orange for the remainder of the reporting interval.
|Figure 3. Ashfall from Tolbachik was reported in Krasny Yar (~60 km NNW). Two deposits are distinguishable, separated by fresh snowfall; lens cap for scale. Courtesy of Y. Demyanchuk (IVS FED RAS) and KVERT.|
KVERT reported on 28 November that the N and S fissures were located 4-5 km and 6-7 km S of Plosky Tolbachik, respectively. Plosky Tolbachik is a shield volcano with nested summit calderas that makes up the E half of Tolbachik; the W portion of Tolbachik is the sharply-peaked Ostry Tolbachik stratovolcano (figures 1 and 4). At that time, Strombolian activity (figure 5) was observed at 4-5 vents in the N fissure and 2-3 vents in the S fissure; the very fluid lavas (figure 6) were flowing, often in 'lava rivers', to the W side of Tolbachinsky Dol (figure 7), and KVERT noted a large thermal anomaly over the N part of Tolbachinsky Dol (figure 8). Observers reported booming noises and vibrating windowpanes.
|Figure 5. Strombolian activity during the eruption from the S fissure of Tolbachinsky Dol on 29 November 2012. Courtesy of S. Samoilenko and A. Sokorenko (IVS FEB RAS) and KVERT.|
On 29 November, seismicity declined, and KVERT characterized the eruption as effusive; renewed seismicity occurred the next day, and a gas-and-steam plume with small amounts of ash rising to ~3 km was reported. Lava flows from the N fissure destroyed two scientific base camps located ~10 km from Tolbachik.
Cinder cones grow on S fissure; new fumarole. A KVERT weekly report issued on 6 December 2012 noted that cinder cones were growing on the S fissure, and that lava effused from the S fissure had flowed up to 20 km away by 7 December. A fumarole was observed at the bottom of the Plosky Tolbachik caldera on 8 December (figure 9); this was the first fumarole observed in the caldera in ~30 years. On 9 December KVERT daily reports began stating that the effusion of lava was continuing from the S fissure, no longer mentioning the N fissure.
|Figure 9. A new fumarole that was observed in the Plosky Tolbachik caldera on 8 December 2012. KVERT reported that this is the first fumarole in the caldera in ~30 years. Courtesy of O. Evdokimova (IVS FEB RAS) and KVERT.|
By the end of December, KVERT reported that five cinder cones were growing on the S fissure (e.g. figure 10); by 10 January 2013, however, KVERT reported only four cinder cones on the S fissure.
|Figure 10. Strombolian activity within a cinder cone on the S fissure of Tolbachinsky Dol on 27 December 2012. The strombolian activity is feeding a lava river, flowing to the left. Courtesy of Y. Demyanchuk (IVS FEB RAS) and KVERT.|
As of early February 2013, the eruption continued to produce very fluid lava flows, four growing cinder cones, gas-and-steam plumes with variable ash contents that often reached ~4 km a.s.l. and drifted in various directions, and daily thermal alerts above Tolbachinsky Dol. Two examples of eruptive products from the eruption are shown in figure 11.
Geologic Background. The massive Tolbachik basaltic volcano is located at the southern end of the dominantly andesitic Kliuchevskaya volcano group. The massif is composed of two overlapping, but morphologically dissimilar volcanoes. The flat-topped Plosky Tolbachik shield volcano with its nested Holocene Hawaiian-type calderas up to 3 km in diameter is located east of the older and higher sharp-topped Ostry Tolbachik stratovolcano. The summit caldera at Plosky Tolbachik was formed in association with major lava effusion about 6500 years ago and simultaneously with a major southward-directed sector collapse of Ostry Tolbachik volcano. Lengthy rift zones extending NE and SSW of the volcano have erupted voluminous basaltic lava flows during the Holocene, with activity during the past two thousand years being confined to the narrow axial zone of the rifts. The 1975-76 eruption originating from the SSW-flank fissure system and the summit was the largest historical basaltic eruption in Kamchatka.
Information Contacts: Kamchatkan Volcanic Eruption Response Team (KVERT), Institute of Volcanic Geology and Geochemistry, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Yelizovo Airport (UHPP), Petropavlovsk-Kamchatsky, Kamchatka Krai, Russia; NASA Earth Observatory, NASA Goddard Space Flight Center (URL: http://earthobservatory.nasa.gov/); NASA Jet Propulsion Laboratory, California Institute of Technology (URL: http://www.jpl.nasa.gov/); Wikipedia (URL: http://www.wikipedia.org/).