23 years of quiet ended by occasional minor 2012-2013 eruptions

Etorofu-Yakeyama (Ivan Grozny or Grozny Group) rests on E-central Iturup Island (known as Etorofu-to in Japanese and Ostrov Iturup in Russian) (figures 4 and 5). An andesitic lava dome forms the peak, and the complex also includes a ~3-3.5 km long caldera open to the S. The complex erupted multiple times during 1968-1989. Several minor eruptions occurred during 2012 and 2013. Our previous report (BGVN 17:12) described a 3 May 1989 eruption. The Japan Meteorological Agency (JMA), the Tokyo Volcano Ash Advisory Center (VAAC), and the Sakhalin Volcanic Eruption Response Team (SVERT) were primary sources for this report discussing events as late as April 2013 with no further notice of eruptions through July 2014.

Figure 4. Etorofu-Yakeyama on Iturup Island and the regional area including Hokkaido, Japan (more than 200 km SW) and Sakhalin, Russia (more than 350 km NW). Three settlements on Iturup Island are noted here: Kuril'sk, Goyachiye Klyuchi, and Burevestnik. Green triangles indicate volcanic centers. Annotated GoogleMap image.

Figure 5. Etorofu-Yakeyama located on a topographic map (100 m contour lines). Etorofu-Yakeyama sits ~6 km from the Pacific Ocean shore and ~14 km SW of the stratovolcano Sashiusudake (also known as Baransky). Map published by the Geospatial Information Authority of Japan and annotated with placenames from JMA reports.

2012 eruptions. According to SVERT, Etorofu-Yakeyama erupted on 16 August 2012, for the first time since 1989. The plume from the lava dome inside the caldera resulted in light ashfall in the Goryachiye and Kuril`sk settlements (to the N; figure 4). JMA reported the eruption started on 15 August and ended on 26 August 2012 as noted in table 1. Based on MTSAT-2 satellite images, JMA noted an ash plume reached 4 km altitude on 25 August. The Tokyo VAAC issued a Volcanic Ash Advisory (VAA) on 25 August. No additional ash observations were issued after 25 August 2012.

Table 2. A synopsis of eruptions that took place at Etorofu-Yakeyama during 1968-2012. Taken from the JMA website.

On 16 August 2012, F. Greenberg, a Sakhalin Region Emergency Ministry representative, reported that gas emissions on the NE slope had increased on 14 August which suggested unrest. Hokkaido University researchers associated with JMA visited Etorofu-to Island and reported eruptive activity started on 15 August.

Four eruptions occurred during 25-26 August. One plume rose 4-5 km. Figure 6 shows the volcano erupting on 25 August 2012. The next day in the same general area the researchers reported fumarolic activity on the NE side where the ash plume vented (figure 7). SVERT reported during 23 August-3 September increased fumarolic activity at Etorofu-Yakeyama. The Aviation Color code during that interval was Yellow.

Figure 7. Etorofu-Yakeyama seen during an eruption as viewed from NW on 25 August 2012. Courtesy of JMA and Hokkaido University. Photo by M. Nakagawa.

Figure 8. Etorofu-Yakeyama during fumarolic activity viewed from N on 26 August 2012. The double peaked dome to the left of the active Yakeyama/Grozny dome is called Eboshizan. Courtesy of JMA and Hokkaido University. Photo by M. Nakagawa.

2013 eruptions. Ash fall was reported several times during February-April 2013. SVERT reported that on 16 February, a gas and ash plume rose to an altitude of about 3 km. Tokyo VAAC reported a possible eruption occurred on 29 March. The possible ash plume rose to 2.1 km and drifted E.

On 3 April 2013 an eruption took place that was later reported by Interfax, Russia & FSU General News. 2-3 mm of ash was deposited on Kuril`sk and other settlements. Plume height was not recorded due to cloud cover in the area. On 4 April, the Tokyo VAAC detected an ash plume with an altitude of ~3 km drifting W and NW in satellite images. No additional ash observations were issued after 4 April 2013.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (Tokyo VAAC) (URL: https://ds.data.jma.go.jp/svd/vaac/data/); Sakhalin Volcanic Eruption Response Team (SVERT) (URL: http://www.imgg.ru/en/svert.html); EMERCOM Crisis Management Centre (URL: http://en.mchs.ru/Forces_and_Facilities/National_Emergency_Management_Centre); Sakhalin Institute of Marine Geology and Geophysics Institute of Marine Geology and Geophysics FEB RAS (IMGG FEB RAS), 693022, Russia, Yuzhno-Sakhalinsk, Nauki str. 1B (URL: http://www.imgg.ru/); RIA Novosti (URL: http://en.rian.ru/); Itar-Tass (URL: http://tass.ru); and Interfax, Russia, & FSU General News (URL: http://connection.ebscohost.com).

Information is preliminary and subject to change. All times are local (unless otherwise noted)

July 1973 (CSLP 92-73)

Single weak explosion

Card 1684 (27 July 1973) Single weak explosion

. . . at the beginning of the year there was a single weak explosion from the volcano "Ivan Grozny" on the island of Iturup.

Information Contacts: Y.M. Doubik, IV.

May 1989 (SEAN 14:05) Cite this Report

Ash eruption; earthquakes and tremor

An abrupt increase in white fumarolic emissions, accompanied by weak explosions of gas and black ash, was observed . . . 3-4 May. A seismograph in Kurilsk (~30 km from the volcano) recorded weak earthquakes at various depths and short-period volcanic tremor for the following 5 days [see also 15:2]. On 8 May at 1330, a strong explosion ejected a black ash column that reached 1,500-1600 m above the summit within 8 minutes. By 1402, winds were dispersing the plume. A low-frequency rumble was heard in Kurilsk and Goryachie Kluchi (9 km W) during the eruption, but witnesses on the Pacific coast (6-8 km S) heard no sounds. On 11 May, images from a NOAA polar orbiting satellite at 1400 and Japan's GMS satellite at 1900 showed no volcanic plume. Small ash explosions occurred after 14 May, and as of 26 May, steam/gas emissions were continuing. More than a week before the eruption, a report in the 25 April Sovetskii Sakhalin newspaper warned that the residents of Goryachie Kluchi village would be at risk if an explosion should occur.

Before the eruption, fumarolic activity was concentrated in the N block along a wide fracture that extended 250-300 m down the W slope from the summit. Geologists who flew over the volcano in a helicopter and airplane 10 days after the eruption (on 18 and 20 May) observed a narrow mudflow, ~20-30 m wide and 1 km long, on the E slope. Fumarolic activity was still visible in the upper portion of the N block fracture. Fumaroles were also observed in the saddle separating the blocks of the dome, near the E slope.

Further Reference. Abdurakhmanov, A.I., Zlobin, T.K., Markhinin, E.K., and Tarakanov, R.Z., 1990, The Ivan Groznyi volcano eruption on the Iturup Island in 1989: Volcanology and Seismology, no. 4, p. 3-9 (in Russian); v. 12, p. 423-430 (in English).

Information Contacts: G. Steinberg, V. Ostapenko, and R. Bulgakov, Yuzhno-Sakhalinsk; G. Bogoyavlenskaya and I. Menyailov, IV; T. Baldwin, NOAA/NESDIS.

December 1989 (SEAN 14:12) Cite this Report

Small explosions form new fumaroles; mudflows

After an increase in fumarolic emissions and weak ash explosions in May, fumarolic activity remained vigorous. An eruption on 19 June at 2230, accompanied by 2-3 minutes of weak rumbling, sent ash and gas to ~2 km. An early August explosion formed new fumarolic vents on the dome's N flank, ~70-100 m from the summit (figure 1).

Figure 1. September 1989 photograph by A. Samoluk, looking W at the new fumaroles formed by an August explosion on the dome's N side.

On a 16 September ascent of the dome, geologists G. Steinberg and S Tkachenko observed vigorous gas emission from several sulfur-encrusted fissures, and deep narrow craters ~2-3 m in diameter. Two mud flows (4-6 m wide) that extended 1.5-2 km down the dome's N side had destroyed areas of thick vegetation (bushes and bamboo). One flow reached Lake Lopastnye (figure 2). No juvenile material was found in the flows. A small mudflow deposit on the S side of the dome, and another on the W (previously seen 18 and 20 May; reported as E slope in 14:5) were also observed.

Figure 2. September 1989 photograph by A. Samoluk, looking S at two mudflows on the dome's N side. Lake Lopastnye is in the foreground.

Information Contacts: G. Steinberg and R. Bulgakov, Yuzhno-Sakhalinsk.

February 1990 (BGVN 15:02) Cite this Report

New fumaroles formed after predicted ash eruption in June

After the May 1989 activity, geologists performed aerial and field investigations at the request of local authorities. They forecast that vigorous fumarolic activity and rare weak explosions would continue through August, and this assessment was printed in the regional newspaper Suvorovsky Natisc on 15 June 1989, 4 days before the June eruption. Moderate fumarolic activity continued in June.

Seismic activity in a 100-m-wide zone extending NE across the volcano had increased March-May 1989. According to R.Z. Tarakanov, the earthquakes were at 30 and 60 km depths.

Aerial observations in August revealed a new group of fumaroles in the NNE part of the dome. During their 16 September ascent of the dome, Steinberg and Tkachenko measured gas temperatures of 100-104°C. Deep, narrow, craters had formed at the intersections of en-echelon fissures, and the surface around them was covered by andesitic ash (table 1). It is not yet known if the material was juvenile.

Table 1. Chemical analyses of ash samples collected from fissures in Ivan Grozny's summit dome. Analytical values are volume percent of dry gas. Courtesy of G. Steinberg.

Fumarolic activity was distributed along the summit crater fissure. Before the May explosions, emissions had been observed over the entire cross-section of the crater's fissure and on the E slope of the dome. No fumarolic activity was observed in August on the E outer slope of the dome, only from its uppermost W portion. The floor of the E part of the crater was covered with 30 cm of ash but exhibited no fumarolic activity.

At the request of the local authorities, geologists forecast (and published in the local newspaper Krasny Mayak on 28 September) that the volcano's activity should continue at its present level through February 1990.

Information Contacts: G. Steinberg and R. Bulgakov, Yuzhno-Sakhalinsk.

December 1992 (BGVN 17:12) Cite this Report

Additional details about 1989 eruption

The following description of the 1989 eruption includes information supplementing 14:5 and 14:12. The eruption began on 3 May, as gas emission became more intense in the trench at the central dome's summit and on the dome's NE flank. Ash rose to ~1.5 km above the summit on 8 May. Weaker ash eruptions took place 9-13 May, and lahars were triggered by intense snowmelt. The E lahar moved >600 m down the dome, spreading at its base to form a lithic-rich deposit ~200 m across. Other lahars, no wider than 3-5 m, flowed N toward Lake Lopastnoye (figure 3), destroying dense stands of bamboo; one lahar entered the lake. After the May eruption, gas emission was concentrated in the summit fissure, and gas was no longer emerging from fissures on the dome's NE flank.

Figure 3. Sketch map of Ivan Grozny, showing 1990 gas-sampling sites. Courtesy of G. Steinberg.

Small ash eruptions occurred again on 19 May and during the first 10 days of August. After the August activity, a new zone of fumaroles was observed on the NE part of the dome, 40-50 m below the fissure's N edge. Fissures 2-3 m wide and funnel-shaped vents 4-5 m in diameter that had ejected ash had formed on the NE part of the dome. S and Cl-rich water vapor was emitted vigorously from the new vents and fissures. Gas emission had nearly stopped from the E end of the summit fissure, where its floor was flat and covered with cooled ash. No juvenile material was found in the 1989 tephra.

Information Contacts: G. Steinberg, Yuzhno-Sakhalinsk.

April 2014 (BGVN 39:04) Cite this Report

23 years of quiet ended by occasional minor 2012-2013 eruptions

Etorofu-Yakeyama (Ivan Grozny or Grozny Group) rests on E-central Iturup Island (known as Etorofu-to in Japanese and Ostrov Iturup in Russian) (figures 4 and 5). An andesitic lava dome forms the peak, and the complex also includes a ~3-3.5 km long caldera open to the S. The complex erupted multiple times during 1968-1989. Several minor eruptions occurred during 2012 and 2013. Our previous report (BGVN 17:12) described a 3 May 1989 eruption. The Japan Meteorological Agency (JMA), the Tokyo Volcano Ash Advisory Center (VAAC), and the Sakhalin Volcanic Eruption Response Team (SVERT) were primary sources for this report discussing events as late as April 2013 with no further notice of eruptions through July 2014.

Figure 4. Etorofu-Yakeyama on Iturup Island and the regional area including Hokkaido, Japan (more than 200 km SW) and Sakhalin, Russia (more than 350 km NW). Three settlements on Iturup Island are noted here: Kuril'sk, Goyachiye Klyuchi, and Burevestnik. Green triangles indicate volcanic centers. Annotated GoogleMap image.

Figure 5. Etorofu-Yakeyama located on a topographic map (100 m contour lines). Etorofu-Yakeyama sits ~6 km from the Pacific Ocean shore and ~14 km SW of the stratovolcano Sashiusudake (also known as Baransky). Map published by the Geospatial Information Authority of Japan and annotated with placenames from JMA reports.

2012 eruptions. According to SVERT, Etorofu-Yakeyama erupted on 16 August 2012, for the first time since 1989. The plume from the lava dome inside the caldera resulted in light ashfall in the Goryachiye and Kuril`sk settlements (to the N; figure 4). JMA reported the eruption started on 15 August and ended on 26 August 2012 as noted in table 1. Based on MTSAT-2 satellite images, JMA noted an ash plume reached 4 km altitude on 25 August. The Tokyo VAAC issued a Volcanic Ash Advisory (VAA) on 25 August. No additional ash observations were issued after 25 August 2012.

Table 2. A synopsis of eruptions that took place at Etorofu-Yakeyama during 1968-2012. Taken from the JMA website.

On 16 August 2012, F. Greenberg, a Sakhalin Region Emergency Ministry representative, reported that gas emissions on the NE slope had increased on 14 August which suggested unrest. Hokkaido University researchers associated with JMA visited Etorofu-to Island and reported eruptive activity started on 15 August.

Four eruptions occurred during 25-26 August. One plume rose 4-5 km. Figure 6 shows the volcano erupting on 25 August 2012. The next day in the same general area the researchers reported fumarolic activity on the NE side where the ash plume vented (figure 7). SVERT reported during 23 August-3 September increased fumarolic activity at Etorofu-Yakeyama. The Aviation Color code during that interval was Yellow.

Figure 7. Etorofu-Yakeyama seen during an eruption as viewed from NW on 25 August 2012. Courtesy of JMA and Hokkaido University. Photo by M. Nakagawa.

Figure 8. Etorofu-Yakeyama during fumarolic activity viewed from N on 26 August 2012. The double peaked dome to the left of the active Yakeyama/Grozny dome is called Eboshizan. Courtesy of JMA and Hokkaido University. Photo by M. Nakagawa.

2013 eruptions. Ash fall was reported several times during February-April 2013. SVERT reported that on 16 February, a gas and ash plume rose to an altitude of about 3 km. Tokyo VAAC reported a possible eruption occurred on 29 March. The possible ash plume rose to 2.1 km and drifted E.

On 3 April 2013 an eruption took place that was later reported by Interfax, Russia & FSU General News. 2-3 mm of ash was deposited on Kuril`sk and other settlements. Plume height was not recorded due to cloud cover in the area. On 4 April, the Tokyo VAAC detected an ash plume with an altitude of ~3 km drifting W and NW in satellite images. No additional ash observations were issued after 4 April 2013.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (Tokyo VAAC) (URL: https://ds.data.jma.go.jp/svd/vaac/data/); Sakhalin Volcanic Eruption Response Team (SVERT) (URL: http://www.imgg.ru/en/svert.html); EMERCOM Crisis Management Centre (URL: http://en.mchs.ru/Forces_and_Facilities/National_Emergency_Management_Centre); Sakhalin Institute of Marine Geology and Geophysics Institute of Marine Geology and Geophysics FEB RAS (IMGG FEB RAS), 693022, Russia, Yuzhno-Sakhalinsk, Nauki str. 1B (URL: http://www.imgg.ru/); RIA Novosti (URL: http://en.rian.ru/); Itar-Tass (URL: http://tass.ru); and Interfax, Russia, & FSU General News (URL: http://connection.ebscohost.com).