Chirinkotan

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  • 48.98°N
  • 153.48°E

  • 724 m
    2375 ft

  • 290260
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Most Recent Weekly Report: 6 May-12 May 2015


SVERT reported that on 10 May a thermal anomaly over Chirinkotan was detected in satellite images. Cloud cover prevented views of the volcano on the other days during 4-11 May. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


Most Recent Bulletin Report: December 2014 (BGVN 39:12)


Through April 2015, thermal anomalies & gas-steam plumes continue
Download or Cite this Report

[What follows is the latest corrected report (put online in late May 2015) taking advantage of new information.]

Korovin is a stratovolcano located on Atka Island in the central Aleutian Islands (figure 1 in BGVN 23:06 and figure 2 in BGVN 31:11). Korovin’s most recent reported activity ended in 2007. This Bulletin report summarizes and contains new information on activity at Korovin from 1998 to 2007 by drawing on information primarily from the Alaska Volcano Observatory (AVO) and their cited publications. Much of the summary takes the form of a table at the end of the report.

Previous Bulletin reports, which were listed under Atka on our website, address past activity at Korovin. These reports are now listed under Korovin on our website. This occurred because Simkin and Siebert (1994) listed all volcanoes on the northern part of Atka Island, including Korovin, under Atka. Later, Siebert and others (2009) listed Korovin as a separate volcano distinct from Atka. Eruptions in 2005 and early 2006 are discussed in BGVN 31:02 and eruptions in late 2006 in BGVN 31:11.

In this Bulletin report, we start by providing background information on the Atka volcanic complex within which Korovin is located, as well as information on Korovin.

xxxAtka volcanic complex. According to Myers and others (2002) Korovin is a part of the 360 km2 Atka volcanic complex, found on the northern part of Atka Island. It is the largest modern complex within the central Aleutians (Myers and others, 2002). The ancestral Atka volcano, in the complex, was described as a large shield volcano consisting of basaltic and basaltic andesite flows, which was subsequently surrounded by a series of satellite vents (Myers and others, 2002).

A caldera forming eruption at the Atka shield volcano occurred ~300,000-500,000 years ago, creating a 5 km diameter caldera. Associated with that event was the eruption of a large dacitic flow, called Big Pink. Regarding the composition of Big Pink, Myers and others (2002) said, “It consists of pumiceous and glassy units but is not associated with any ash flows.” After the caldera formation, the volcanic centers of Korovin, Kliuchef, Konia and Sarichef formed. ::: Figure 4 is a topographic map showing the location of these four volcanic centers and the location of the Atka caldera. These structures all comprise the Atka volcanic complex.

Korovin volcano. Korovin is located 21 km NE from the town of Atka (::: figure 4). Korovin is the largest and tallest volcano of the post-caldera volcanic centers within the Atka volcanic complex. According to Myers and others (2002), Korovin shows little evidence of glaciation, unlike Kliuchef, located ~5 km S of Korovin. Regarding Korovin’ edifice and age, Myers and others (2002) say “Its uneroded form suggests the volcano is mostly Holocene in age.”

Korovin has a basal diameter of ~7 km and two summit vents located 0.6 km apart (Myers and others, 2002). The NW summit vent has a small crater and is the lower of the two vents. The SE summit has a 1 km wide crater, with steep walls and a depth of several hundred meters (Myers and others, 2002). The SE summit crater sometimes contains a crater lake and is considered Korovin’s active crater. ::: figure 5 is an aerial photo of Korovin, highlighting its two summit vents.

Figure 5. Photograph of Korovin volcano taken from an aircraft flying at 9.1 km altitude on 5 August 2007. The view is oblique and from the N (i.e. looking S). Steam is rising from the active crater (SE crater). The summit of Kliuchef volcano is partially visible at the top of the image; it sits ~5 km S of Korovin. Photograph taken by Burke Mees, Alaska Airlines. Photograph from McGimsey and others (2011).

During the summer of 2004, AVO installed a network of seismic stations throughout the northern part of Atka Island. Data from the network was accessible in March 2005; however, it wasn’t until December 2005 that Korovin was considered seismically monitored. On 2 December 2005, Korovin was also officially assigned the Level of Concern Color Code Green after “a sufficient period of background seismicity had been recorded” (McGimsey and others, 2007). Before, AVO had listed Korovin as UA (unassigned) during periods when no significant activity was noted. AVO assigns volcanoes UA when there is no real-time seismic network in the area that can be used to define background levels of seismicity.

In addition to being seismically monitored, Korovin is also monitored through ground-based, aerial, and satellite imagery and photographs. Korovin and its plumes are often photographed by residents of Atka village (::: figures 6 and 7), which are then sent to the AVO. ::: Figure 8 provides examples of photos of Korovin taken from satellites. Images from ::: figures 6-8 furnish various kinds of evidence, from steaming (i.e. non-eruptive cases, ::: figure 7), ash-bearing plumes (::: figure 6), and the result of ash-bearing eruptions (ash on the snow surface seen in satellite views, ::: figure 8). Evidence of these kinds is summarized in next section.

Figure 6. Photographs showing the progression of a steam plume that developed over Kovorin around 1900 on 23 February 2005. Plume was observed drifting to the E, and ash was seen falling out near the base of the plume. These photos were taken in Atka village and are courtesy of Louis and Kathleen Nevzoroff. Photos were taken from McGimsey and others (2008). Figure 7. Photograph of a steam column rising from Korovin on 27 July 2007. Steam was estimated to reach ~215-245 m above the crater. The photo was captured by Louis Nevzoroff from Atka village. Taken from McGimsey and others (2011). Figure 8. Two satellite photographs showing ash deposits on the upper E flank of Korovin in 2002 (top) and 2004 (bottom). The source of these ash deposits is thought to be intermittent, minor phreatic eruptions through the hot, roiling lake within the SE summit crater of Korovin (McGimsey and others, 2007). Top image was taken on 5 July 2002 and produced by the Image Analysis Laboratory, NASA Johnson Space Center. Bottom image was captured on 4 July 2004 and is an Ikonos near-infrared color composite, copyrighted by Space Imaging LLC. Both images originally published in McGimsey and others (2008).

Defining the term ‘eruption.’ There is no universally agreed-upon definition for the term ‘eruption’. McGimsey and others (2011) however, follow the GVP’s eruption definition where an eruption is an event involving explosive ejections of old or new fragmental material, the effusion of liquid lava, or both. Volcanically produced heat and near-surface water can interact explosively causing a dramatic eruption, which may or may not bring fresh volcanic material to the surface.

McGimsey and others (2011) go onto say, “The element of this definition we wish to emphasize are the verbs ‘eject’ and ‘effuse’ which refer to dynamic surface processes that pose some level of hazard. The presence or absence of often ambiguous ‘juvenile material’ or fresh magma is not relevant to this use of the term eruption, particularly when communicating a potential hazard that makes no distinction between juvenile and non-juvenile eruption products. This definition would not, however, include passive volcanic degassing or hydrothermal-fluid discharge unless accidental solid fragments are entrained.”

1998-2007 activity at Korovin. In this section of the Bulletin report, we summarize the volcanic activity at Korovin that took place between 1998 and 2007 (table 1). During this interval, activity ranged from eruptive cases to those that were considered non eruptive.

Activity was often reported to AVO by Atka village residents and pilots in the area. Korovin was also monitored through satellite imagery, when weather conditions were favorable. During this interval, the highest plumes were observed on 30 June 1998 and reached an altitude of ~9.1 km. As activity varied at Korovin, the Aviation Color Code (ACC), the Volcanic Activity Alert Level (VAAL), and the Level of Concern Color Code (LCCC) were changed to reflect Korovin’s activity status.

On their website, AVO presented general information on Korovin’s reported activity from 1998-2007. For each of the events within this interval, AVO cited information from several sources, some of which included the following: McGimsey and others (2003), which discussed activity in 1998; McGimsey and others (2008), which discussed 2005 activity; Neal and others (2009) that looked at 2006 activity; and McGimsey and others (2011) that detailed 2007 activity. AVO also referenced several past Bulletin reports, which highlighted Korovin activity (BGVN 23:06, and 31:02).

Our summary in table 1 summarizes the following: (1) the basic information on Korovin’s activity from the AVO website and (2) additional information from some of AVO’s cited references. Greater detail can be found on AVO’s website and in their cited references.

Table 1 contains two columns, entitled Date and Remarks. The Date column refers to the year of Korovin activity. The Remarks column generally contains the following: (1) “AVO:” This presents a very brief synopsis of the summary that AVO provides on each of their Korovin reported activity web pages (as accessed in May 2015). (2) Below that, we present a succinct timeline of Korovin activity created using on information found in some of AVO’s cited references.

In table 1, please note we have separated 2005 activity into two rows, to highlight two different periods of activity during that year. Also note that 2006-2007 is considered one period of activity and is therefore detailed in one section (i.e., one row).

Table 1. Table that condenses key events at Korovin during both eruptive and non-eruptive periods during 1987-2007. The data sources are stated in the table. Where AVO cited references are augmented by past Bulletin reports, the information has been [bracketed]. Times are all local, unless otherwise stated. The term ‘resident(s)’ refers to resident(s) of Atka village. Abbreviations used are as follows: Village Public Safety Officer, VPSO; above sea level, a.s.l., and Interferometric synthetic aperture radar, InSAR; Aviation Color Code, ACC; Volcanic Activity Alert Level, VAAL; Level of Concern Color Code, LCCC; unassigned activity (UA); and satellite-based Ozone Monitoring Instrument, OMI.

Date Remarks
1998

AVO:

Eruption started, 30 June 1998 ±1 month. Eruption end, 30 June 1998 ± 7 days

 

McGimsey and others (2003):

Eruption start / stop dates: 30 June / 8 July

“…, the timing of this activity remains poorly constrained; intermittent ash may, in fact, have occurred weeks or prior to June 30.”

10 May- Pilot observed ash on SE slope. Pilot had seen no ash the previous week and speculated the ash was deposited a few days prior to May 10

28 June-Individual reported a dark ash plume over Korovin

30 June-VPSO in Atka village reported two separate clouds, first at ~0730 and second at ~0830. Second cloud rose ~9.1 km and was tinted orange. VPSO said events “produced dustings of ash in Atka”. AVO received 2 pilot reports: (1) at 1115, noted volcanic cloud reached ~4.9 km a.s.l., (2) at 1720, cloud to 9.1 km near Korovin

2 July- Resident reported a ‘rusty’ cloud, ~4.9 km a.s.l. moving SE

3 July- Pilot reported profuse steam from summit crater and ash on S, SE and E flanks. Thin trail of ash extended SW towards Atka village

8 July- AVO noted minor, weakly ash-bearing clouds over Korovin with satellite images

2002 AVO:

Eruption started, July 2002 ±1 month. Considered a questionable eruption

 

McGimsey and others (2008):

5 July- Satellite photo of ash deposits on upper E flank of Korovin (::: figure 8 top). “Intermittent, minor phreatic eruptions through a hot, roiling lake in the south summit crater of Korovin [is] the probable source.”

2004 AVO:

Eruption started, June 2004 ±1 month. Considered a questionable eruption

 

McGimsey and others (2008):

4 July- Satellite photograph shows ash deposits on upper E flank of Korovin (::: figure 8 bottoms). Same explanation as 5 July 2002

 

Neal and others (2009):

7 July- Korovin photographed with ash covering the snow on its E flank. According to the caption of the photograph, “The deposit may be the result of phreatic explosions or vigorous wind remobilization of ash from within the summit crater.”

 

19 July- Aerial photograph of Korovin showing ash deposited around the crater vent. The caption for the photograph states, “At times, a shallow body of gray, turbid water partially fills the inner crater and, in 2004, was observed roiling. Phreatic explosions from this water-rich, high-temperature system may be responsible for the occasional localized ash-fall deposits seen on the upper flanks of Korovin.”

2005 AVO:

Eruption started, 23 February. Eruption end, 7 May ± 14 days. Considered a questionable eruption.

 

McGimsey and others (2008):

23 February- Clear day. Residents noted minor steaming around 1200. Around 1900, residents observed dark cloud rising several thousand feet and drifting E (::: figure 6). Ash seen falling out near base of plume. Minutes later, three or four smaller gray puffs seen. No other activity seen that night. In satellite imagery, small steam plume with minor ash noticed. Height of plume estimated at ~3 km (10, 000 ft)

24 February- LCCC was raised from UA (unassigned) to Yellow

4 March- LCCC reduced from Yellow to UA

19 March- Pilot report noted steam rising several thousand feet above Korovin

Early May- Observational data showed roiling lake in SE crater emptied. Visible glow.

2005 AVO:

Seismicity without confirmed eruption, start / end: 13 September

 

McGimsey and others (2008):

13 September- Long sequence of strong seismicity. Sequence began with two small local events, then ~30 minutes of weak tremor, and then ~20 weak local events. Nothing unusual noted in satellite images from this time.

2006-2007 AVO:

Non-eruptive activity started, 16 January 2006 and ended September 2007 ± 2 months.

 

Neal and others (2009):

16 January 2006- Background seismic activity increased

17-18, 21 Jan and 21-22 Feb- burst of tremor-like signals

22 February 2006- LCCC increased from Green to Yellow

Early March- Seismicity stabilized and then decreased

8 March- LCCC downgraded from Yellow to Green

July- Increased number of earthquakes in vicinity of Korovin

September and October- Increased tremor episodes

19 October- SE crater lake disappeared by this date and absent for rest of 2006. Lake present on 12 September (satellite data).

29 October- White vapor plumes rose several hundred meters above Korovin and coincided with ~5-min of strong tremor

5 November 2006- Strongest earthquake swarm recorded by seismic network

6 November- Yellow ACC and an Advisory VAAL declared

18 November- dark-gray ash on E flank of SE crater observed in ASTER satellite images. Ash was not present in image from 21 November. ASTER satellite imagery showed warm spots in Korovin crater

Late November 2006- Significant deformation in latter half of 2006. Circular pattern of uplift, as much as 5 cm noted through July and October InSAR data. November-December- Seismicity high; strong, short-lived signals. Low-frequency tremor bursts.

11, 21 and 24 December 2006- Residents photographed large, white-vapor plumes rising from Korovin. One resident noted that he saw ash falling below the plume he reported. Ash was not verified on the ground

End of 2006-No ash detected in atmosphere or on ground through satellite data. Rise in ground temperature also not detected

McGimsey and others (2011):

Beginning of 2007- ACC, Yellow, and VAAL, Advisory due to increased activity in 2006. High seismicity from 2006 continued into 2007. Inflation (uplift) in N part of Atka Island that began in June 2006 totaled 9-10 cm and began to taper off in 2007

11 January 2007- M3.5 earthquake considered large for volcano-generated seismicity.

23 January- Series of tremor bursts

24 January- Resident took pictures of steam column rising from SE crater and reported similar steam columns rose ~300 m every 15-80 minutes

14 February 2007- Pilot reported a steam plume extending 1.5-2.4 km over Korovin

3 March- Residents photograph ash deposit on W flank. Residents observed steam from SE summit vent. Flurry of low-frequency seismicity in morning

May, June & August- Episodes of tremor lasted several days

27 July 2007- Steam plumes observed by residents (::: figure 7)

5 August- OMI detected small SO2 cloud, 300 km N of Cleveland volcano. Based on wind dispersal models, cloud believed to be from Korovin. Aerial photo (::: figure 5) showed steam rising from SE crater

20 August- OMI detected small emission of SO2 from Korovin

7 September- ACC/VAAL downgraded to Green/Normal due to decreasing trends in seismicity and uplift

October-December 2007- uneventful

References. Alaska Volcano Observatory (AVO), 2014, Korovin Volcano description and information, accessed on 14 April 2015, (URL: http://www.avo.alaska.edu/volcanoes/volcinfo.php?volcname=Korovin)

Alaska Volcano Observatory (AVO), 2014, Korovin reported activity, accessed on 14 April 2015, (URL: http://www.avo.alaska.edu/volcanoes/volcact.php?volcname=Korovin)

Alaska Volcano Observatory, the U.S. Geological Survey, BigTopo 7, and AllTopo 7, Topographic shaded relief image of the northern part of Atka Island (Image 2906), accessed on 14 April 2005, (URL: http://www.avo.alaska.edu/images/image.php?id=2906)

McGimsey, R. G., Neal, C. A., and Girina, O., 2003, 1998 volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 03-0423, 35 pp, (URL: http://pubs.usgs.gov/of/2003/of03-423/)

McGimsey, R.G., Neal, C.A., Dixon, J.P., and Ushakov, S., 2008, 2005 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2007-5269, 94 pp, (URL: http://pubs.usgs.gov/sir/2007/5269/)

McGimsey, R.G., Neal, C.A., Dixon, J.P., Malik, N., and Chibisova, M., 2011, 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2010-5242, 110 pp, (URL: http://pubs.usgs.gov/sir/2010/5242/)

Myers, J.D., Marsh, B. D., Frost, C. D. and Linton, J.A., 2002, Petrologic constraints on the spatial distribution of crustal magma chambers, Atka Volcanic Center, central Aleutian arc, Contributions to Mineralogy and Petrology, vol. 143, issue 5, pp. 567-586, DOI 10.1007/s00410-002-0356-7 (URL: http://link.springer.com/article/10.1007/s00410-002-0356-7)

Neal, C.A., McGimsey, R.G., Dixon, J.P., Manevich, A., and Rybin, A., 2009, 2006 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2008-5214, 102 pp, (URL: http://pubs.usgs.gov/sir/2008/5214/ )

Simkin, T., and Siebert, L., 1994, Volcanoes of the World (2nd edition), Geoscience Press, 349 pp.

Siebert, L., Simkin, T., & Kimberly, P., 2010, Volcanoes of the World (3rd edition), University of California Press, 551 pp.

Information Contacts: Sakhalin Volcanic Eruptions Response Team (SVERT), Institute of Marine Geology and Geophysics (IMG&G) Far East Division Russian Academy of Sciences (FED RAS), 1B Science St., Yuzhno-Sakhalinsk, 693022, Russia (Email: rybin@imgg.ru, URL: http://www.imgg.ru/).

Weekly Reports - Index


2015: January | February | March | April | May
2014: January | February | March | April | May | June | November | December
2013: May | June | July | August | October | November | December

Weekly Reports


6 May-12 May 2015

SVERT reported that on 10 May a thermal anomaly over Chirinkotan was detected in satellite images. Cloud cover prevented views of the volcano on the other days during 4-11 May. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


29 April-5 May 2015

SVERT reported that on 30 April a thermal anomaly over Chirinkotan was detected in satellite images. Cloud cover prevented views of the volcano on the other days during 27 April-4 May. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


15 April-21 April 2015

SVERT reported that during 17-18 April a thermal anomaly over Chirinkotan was detected in satellite images. Cloud cover prevented views of the volcano on the other days during 13-20 April. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


8 April-14 April 2015

SVERT reported that on 6 April a thermal anomaly over Chirinkotan was detected in satellite images. Weak gas-and-steam emissions were noted on 8 April. Cloud cover prevented views of the volcano on the other days during 7-13 April. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


1 April-7 April 2015

SVERT reported that on 5 April a thermal anomaly over Chirinkotan was detected in satellite images. Cloud cover prevented views of the volcano on the other days during 31 March-6 April. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


25 March-31 March 2015

SVERT reported that on 27 March a thermal anomaly over Chirinkotan was detected in satellite images. Cloud cover prevented views of the volcano on the other days during 23-30 March. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


18 March-24 March 2015

SVERT reported that during 19-21 March a thermal anomaly over Chirinkotan was detected in satellite images. The Aviation Color Code was raised to Yellow on 20 March.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


25 February-3 March 2015

In a report from 4 March SVERT noted that weak steam-and-gas emissions from Chirinkotan were observed in January and February but that volcanic activity was not currently observed; the Aviation Color Code was lowered to Green.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


4 February-10 February 2015

SVERT reported that weak steam-and-gas emissions from Chirinkotan were detected in satellite images on 6 and 8 February. Cloud cover obscured views on the other days during 2-9 February. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


28 January-3 February 2015

SVERT reported that weak steam-and-gas emissions from Chirinkotan were detected in satellite images on 31 January. Cloud cover obscured views on the other days during 26 January-2 February. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


14 January-20 January 2015

SVERT reported that weak steam-and-gas emissions from Chirinkotan were detected in satellite images during 13-14 January. A thermal anomaly was visible on 13 and 15 January. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


7 January-13 January 2015

SVERT reported that steam-and-gas emissions detected in satellite images rose 3 km above Chirinkotan and drifted SE on 5 January. A thermal anomaly was visible during 8 and 10-11 January. Cloud cover obscured views on the other days during 6-12 January. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


31 December-6 January 2015

SVERT reported that a thermal anomaly over Chirinkotan was detected in satellite images on 30 December. Cloud cover obscured views on the other days during 29 December-5 January. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


17 December-23 December 2014

SVERT reported that a thermal anomaly over Chirinkotan was detected in satellite images on 15 and 21 December. Cloud cover obscured views on the other days during 16-22 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


10 December-16 December 2014

SVERT reported that a thermal anomaly over Chirinkotan was detecetd in satellite images during 10-11 and 13-14 December. Cloud cover obscured views on the other days during 8-15 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


3 December-9 December 2014

SVERT reported that satellite images of Chirinkotan showed a thermal anomaly during 2-5 and 7 December, and diffuse gas-and-steam emissions on 3 December. Cloud cover obscured views on the other days during 1-8 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


26 November-2 December 2014

SVERT reported that since 21 November a thermal anomaly and increased gas-and-steam emissions at Chirinkotan were detected in satellite images. A thermal anomaly was detected on 25 November, and a diffuse steam-and-gas plume drifted 40 km SE on 27 November. Steam-and-gas emissions were again observed on 28 and 30 November. The Aviation Color Code was raised to Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


4 June-10 June 2014

SVERT reported that an eruption at Chirinkotan had begun on 24 May; thermal anomalies and gas emissions sometimes containing ash were detected in satellite images. On 5 June seldom and weak thermal anomalies suggested cooling lava flows. The Aviation Color Code was lowered to Green.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


7 May-13 May 2014

SVERT reported that satellite images of Chirinkotan showed gas-and-steam emissions on 7 May. Cloud cover obscured views on the other days during 5-12 May. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


30 April-6 May 2014

SVERT reported that satellite images of Chirinkotan showed a thermal anomaly on 29 April. Cloud cover obscured views during 30 April-5 May. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


23 April-29 April 2014

SVERT reported that satellite images of Chirinkotan showed gas-and-steam emissions on 25 and 27 April. Cloud cover obscured views during 21-28 April. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


16 April-22 April 2014

SVERT reported that satellite images of Chirinkotan showed a thermal anomaly on 14, 15, and 17 April, and gas-and-steam emissions on 20 April. Cloud cover obscured views during 16, 18-19, and 21 April. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


9 April-15 April 2014

SVERT reported that satellite images of Chirinkotan showed gas-and-steam emissions on 9 April drifting more than 50 km SE. Cloud cover obscured views during 10-15 April. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


26 March-1 April 2014

SVERT reported that satellite images of Chirinkotan showed diffuse gas-and-steam emissions on 24 March and steam-and-gas plumes drifting 80-170 km SE during 26-27 March. Cloud cover obscured views on the other days during 25-31 March. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


19 March-25 March 2014

SVERT reported that a steam-and-gas plume from Chirinkotan was observed in satellite images drifting more than 80 km SE on 20 March. Diffuse steam-and-gas emissions were observed during 21-22 March. Cloud cover obscured views on the other days during 17-19 and 23-24 March. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


12 March-18 March 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 10 and 13 March. Steam-and-gas emissions were observed on 10 March and drifted more than 40 km SW on 12 March. Cloud cover obscured views on the other days during 11-17 March. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


5 March-11 March 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 4 March. Cloud cover obscured views during 5-10 March. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


26 February-4 March 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 25 February and gas-and-steam emissions were observed on 27 February. Cloud cover obscured views on other days during 24 February-3 March. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


19 February-25 February 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 20 February. Cloud cover obscured views on other days during 17-24 February. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


12 February-18 February 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 12 and 15 February, and steam-and-gas emissions were observed on 16 February. Cloud cover obscured views on other days during 11-17 February. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


5 February-11 February 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 8 February, and steam-and-gas emissions were observed on 9 February. Cloud cover obscured views on other days during 4-10 February. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


22 January-28 January 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 21 January. Cloud cover obscured views during 22-27 January. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


15 January-21 January 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 15 and 17 January. Gas-and-steam emissions were also observed on 17 January. Cloud cover obscured views on the other days during 14-20 January. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


8 January-14 January 2014

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 9 and 12 January. Cloud cover obscured views on the other days during 7-13 January. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


25 December-31 December 2013

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images during 25-26 December. Cloud cover obscured views on the other days during 23-30 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


18 December-24 December 2013

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 9, 12, and 15 December. Cloud cover obscured views on the other days during 10-16 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


11 December-17 December 2013

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 9, 12, and 15 December. Cloud cover obscured views on the other days during 10-16 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


4 December-10 December 2013

SVERT reported that a weak thermal anomaly over Chirinkotan was observed in satellite images during 2-4 December. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


27 November-3 December 2013

SVERT reported that steam-and-gas emissions from Chirinkotan drifted more than 50 km on 25 November. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


20 November-26 November 2013

SVERT reported that on 22 November a thermal anomaly over Chirinkotan was observed. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


13 November-19 November 2013

SVERT reported that during 13-15 November a thermal anomaly over Chirinkotan was observed, as well as steam-and-gas emissions during 14-15 November. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


6 November-12 November 2013

SVERT reported that during 4-6 November a thermal anomaly over Chirinkotan was observed. Steam-and-gas emissions during 5-6 November drifted 55-100 km SE. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


30 October-5 November 2013

SVERT reported that during 29-31 October, steam-and-gas emissions from Chirinkotan were detected in satellite images; thermal anomalies were also detected during this time. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


23 October-29 October 2013

SVERT reported that during 21-25 October steam-and-gas emissions from Chirinkotan were detected in satellite images. A thermal anomaly was detected on 24 October. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


16 October-22 October 2013

SVERT reported that during 17-19 October a thermal anomaly from Chirinkotan was detected in satellite images along with gas-and-steam emissions drifting 30-60 km SE. Cloud cover prevented observations on the other days during 14-21 October. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


28 August-3 September 2013

SVERT reported that a thermal anomaly from Chirinkotan was detected in satellite images on 1 September. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


14 August-20 August 2013

Based on analysis of satellite images, SVERT reported that a possible thermal anomaly from Chirinkotan was observed on 12 August. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


7 August-13 August 2013

Based on analysis of satellite images, SVERT reported that a thermal anomaly and gas-and-steam emissions from Chirinkotan were observed on 5 and 9 August. A thermal anomaly was visible on 7 August, and possible gas-and-steam emissions were observed on 7 and 8 August. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


31 July-6 August 2013

Based on analysis of satellite images, SVERT reported that a thermal anomaly from Chirinkotan was observed during 29-31 July. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


24 July-30 July 2013

Based on analysis of satellite images, SVERT reported that a thermal anomaly from Chirinkotan was observed on 22 July. Weak steam-and-gas emissions and a weak thermal anomaly were observed on 25 July. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


17 July-23 July 2013

Based on analysis of satellite images, SVERT reported that a thermal anomaly and possible weak steam-and-gas emissions from Chirinkotan were observed on 16 and 18 July. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


10 July-16 July 2013

Based on analysis of satellite images, SVERT reported that weak steam-and-gas emissions from Chirinkotan were observed on 12 July and a thermal anomaly was detected during 12-13 July. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


3 July-9 July 2013

Based on analysis of satellite images, SVERT reported that steam-and-gas emissions from Chirinkotan were observed on 3 July and a thermal anomaly was detected on 4 July. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


26 June-2 July 2013

Based on analysis of satellite images, SVERT reported that steam-and-gas emissions from Chirinkotan were detected on 25 and 26 June. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


19 June-25 June 2013

Based on analysis of satellite images, SVERT reported that a weak thermal anomaly over Chirinkotan was detected on 21 June. A thermal anomaly and steam-and-gas emissions were detected on 23 June.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


12 June-18 June 2013

Based on analysis of satellite images, SVERT reported that dense steam-and-gas emissions, possibly containing ash, rose from Chirinkotan on 11 June. A thermal anomaly was detected on 13 June, and diffuse steam-and-gas emissions were observed on 16 June.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


5 June-11 June 2013

SVERT reported that steam and gas activity at Chirinkotan was observed in satellite imagery on 5, 7, and 9 June.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


22 May-28 May 2013

SVERT reported that steam and gas activity at Chirinkotan was observed in satellite imagery during 24-25 May.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)


Bulletin Reports - Index


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

06/1980 (SEAN 05:06) Lava flows and ash explosions

04/1987 (SEAN 12:04) Ash and gas columns observed

12/2013 (BGVN 38:12) Gas-and-steam emissions and occasional thermal anomalies, beginning May 2013

12/2014 (BGVN 39:12) Through April 2015, thermal anomalies & gas-steam plumes continue




Bulletin Reports

All information contained in these reports is preliminary and subject to change.


06/1980 (SEAN 05:06) Lava flows and ash explosions
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In April 1979, an eruption began from Chirinkotan volcano, which forms an isolated, uninhabited island about 3 km in diameter. Block lava flowed down the SSW flank in April and May. Ash explosions occurred regularly during the summer of 1979 and explosive activity increased in October. In January and April 1980, moderate explosions occurred 1-2 times per hour.

Information Contacts: G. Steinberg, Sakhalin Complex Institute.

04/1987 (SEAN 12:04) Ash and gas columns observed
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Chirinkotan was observed from the air 11, 12, and 31 October, and 2 November. A thick gas and ash column reached 700-800 m above the crater, and drifted 6-8 km downwind on 11 October. Intense gas emission occurred throughout the crater. On 12 October gas emission was less intense but a gas cloud reached 400-600 km high and was 3-4 km long despite a strong wind. By 31 October fumarolic activity had diminished significantly. On the E crater slope a few groups of large fumaroles were observed. A gas plume 200 m in diameter was 250 m high and 800-900 m long. Flank ashfall had been covered by snow that fell 12-13 October. Activity was similar on 2 November.

Information Contacts: G. Steinberg and B. Piskunov, Yuzhno-Sakhalinsk.

12/2013 (BGVN 38:12) Gas-and-steam emissions and occasional thermal anomalies, beginning May 2013
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In 1979-1980, an eruption at Chirinkotan included a series of ash explosions and a lava flow (SEAN 05:06). In October and November 1986, airborne observers saw a column of thick gas and ash, and then fumarolic activity (SEAN 12:04). This report discusses events during 2013 through April 2014. The location of Chirinkotan in the Kuril Islands is shown in figure 1.

Figure 1. Map showing location of Chirinkotan. Courtesy of Google Earth.

According to the Sakhalin Volcanic Eruption Response Team (SVERT), gas-and-steam emissions occurred frequently in 2013-2014 (table 1). The Aviation Color Code was Green on 24-25 May 2013, when emissions were first reported, but raised to Yellow during early June 2013, where it has remained through April 2014, the end of this report. The volcano was often obscured by clouds.

According to the U.S. Geological Survey, an M 8.3 earthquake occurred on 24 May 2013 beneath the Sea of Okhotsk, at a point is 656 km N of the volcano. The focal depth of the earthquake was ~ 600 km. The first reported gas-and-steam emission from Chirinkotan, which is in the Sea of Okhotsk, was on 24-25 May, suggesting a possible link between the two events.

Table 1. SVERT-reported dates on which gas-and-steam emissions were observed from 24 May 2013 through 30 April 2014, based on analysis of satellite images. Thermal alerts detected by SVERT and the MODVOLC satellite thermal alert system are also noted.

Date Comments
24-25 May 2013 Gas-and-steam emissions
5, 7, 9 Jun Gas-and-steam emissions
11 Jun Strong gas-and-steam emission, possibly with ash
13 Jun SVERT-reported thermal alert
16 Jun Gas-and-steam emissions
21 Jun SVERT-reported thermal alert
23 Jun Gas-and-steam emissions
3 Jul Gas-and-steam emissions
4 Jul SVERT-reported thermal alert
12 Jul Gas-and-steam emissions and SVERT-reported thermal alert on 12-13 Jul
16, 18 Jul Gas-and-steam emissions and SVERT-reported thermal alert
22 Jul MODVOLC thermal alert and SVERT-reported thermal alert
25 Jul Gas-and-steam emissions
29-31 Jul SVERT-reported thermal alert
2 Aug MODVOLC thermal alert
5-9 Aug Gas-and-steam emissions and SVERT-reported thermal alerts on 5, 7, and 9 Aug
12 Aug SVERT-reported thermal alert
1 Sep MODVOLC thermal alert (twice) and SVERT-reported thermal alert
28 Sep MODVOLC thermal alert
4 Oct MODVOLC thermal alert (3 pixels)
17-19 Oct Gas-and-steam emissions drifted 30-60 km SE and SVERT-reported thermal alert
21-25 Oct Gas-and-steam emissions and SVERT-reported thermal alert on 24 Oct
29-31 Oct Gas-and-steam emissions and SVERT-reported thermal alert
4 Nov MODVOLC thermal alert (2 pixels) and SVERT-reported thermal alert
5-6 Nov Gas-and-steam emissions drifted 55-100 km SE and  SVERT-reported thermal alerts
11 Nov MODVOLC thermal alert (2 pixels)
13 Nov MODVOLC thermal alert (2 times) and SVERT-reported thermal alert
14-15 Nov Gas-and-steam emissions and SVERT-reported thermal alert
22 Nov SVERT-reported thermal alert
25 Nov Gas-and-steam emissions drifted more than 50 km SE
27 Nov MODVOLC thermal alert
1 Dec MODVOLC thermal alert (4 pixels)
2-4, 9 Dec SVERT-reported thermal alerts
11 Dec MODVOLC thermal alert
12, 15 Dec SVERT-reported thermal alerts
18 Dec Gas-and-steam emissions
25-26 Dec SVERT-reported thermal alert
9, 12, 15 Jan 2014 SVERT-reported thermal alert
17 Jan Gas-and-steam emissions and SVERT-reported thermal alert
21 Jan SVERT-reported thermal alert
8 Feb MODVOLC thermal alert and SVERT-reported thermal alert
9 Feb Gas-and-steam emissions
12, 15 Feb SVERT-reported thermal alerts
16 Feb Gas-and-steam emissions
20, 25 Feb SVERT-reported thermal alert
27 Feb Gas-and-steam emissions
4 Mar SVERT-reported thermal alert
7 Mar MODVOLC thermal alert
8 Mar MODVOLC thermal alert (2 times, 3 pixels on Terra satellite)
12 Mar Gas-and-steam emissions drifted 80 km SE and MODVOLC thermal alert
17 Mar MODVOLC thermal alert
20 Mar Gas-and-steam emissions drifted 80 km SE
21-24 Mar Gas-and-steam emissions
26 Mar Gas-and-steam emissions drifted 80 km SE
27 Mar Gas-and-steam emissions drifted 170 km SE
9 April Gas-and-steam emissions drifted 170 km SE
14, 15, 17 Apr SVERT-reported thermal alert
20, 25, 27 Apr Gas-and-steam emissions
29 Apr SVERT-reported thermal alert

Information Contacts: Sakhalin Volcanic Eruption Response Team (SVERT) (URL in English: http://www.imgg.ru/?id_d=659);Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); and Earthquake Hazards Program, US Geological Survey (URL: http://earthquake.usgs.gov/).

12/2014 (BGVN 39:12) Through April 2015, thermal anomalies & gas-steam plumes continue
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[What follows is the latest corrected report (put online in late May 2015) taking advantage of new information.]

Korovin is a stratovolcano located on Atka Island in the central Aleutian Islands (figure 1 in BGVN 23:06 and figure 2 in BGVN 31:11). Korovin’s most recent reported activity ended in 2007. This Bulletin report summarizes and contains new information on activity at Korovin from 1998 to 2007 by drawing on information primarily from the Alaska Volcano Observatory (AVO) and their cited publications. Much of the summary takes the form of a table at the end of the report.

Previous Bulletin reports, which were listed under Atka on our website, address past activity at Korovin. These reports are now listed under Korovin on our website. This occurred because Simkin and Siebert (1994) listed all volcanoes on the northern part of Atka Island, including Korovin, under Atka. Later, Siebert and others (2009) listed Korovin as a separate volcano distinct from Atka. Eruptions in 2005 and early 2006 are discussed in BGVN 31:02 and eruptions in late 2006 in BGVN 31:11.

In this Bulletin report, we start by providing background information on the Atka volcanic complex within which Korovin is located, as well as information on Korovin.

xxxAtka volcanic complex. According to Myers and others (2002) Korovin is a part of the 360 km2 Atka volcanic complex, found on the northern part of Atka Island. It is the largest modern complex within the central Aleutians (Myers and others, 2002). The ancestral Atka volcano, in the complex, was described as a large shield volcano consisting of basaltic and basaltic andesite flows, which was subsequently surrounded by a series of satellite vents (Myers and others, 2002).

A caldera forming eruption at the Atka shield volcano occurred ~300,000-500,000 years ago, creating a 5 km diameter caldera. Associated with that event was the eruption of a large dacitic flow, called Big Pink. Regarding the composition of Big Pink, Myers and others (2002) said, “It consists of pumiceous and glassy units but is not associated with any ash flows.” After the caldera formation, the volcanic centers of Korovin, Kliuchef, Konia and Sarichef formed. ::: Figure 4 is a topographic map showing the location of these four volcanic centers and the location of the Atka caldera. These structures all comprise the Atka volcanic complex.

Korovin volcano. Korovin is located 21 km NE from the town of Atka (::: figure 4). Korovin is the largest and tallest volcano of the post-caldera volcanic centers within the Atka volcanic complex. According to Myers and others (2002), Korovin shows little evidence of glaciation, unlike Kliuchef, located ~5 km S of Korovin. Regarding Korovin’ edifice and age, Myers and others (2002) say “Its uneroded form suggests the volcano is mostly Holocene in age.”

Korovin has a basal diameter of ~7 km and two summit vents located 0.6 km apart (Myers and others, 2002). The NW summit vent has a small crater and is the lower of the two vents. The SE summit has a 1 km wide crater, with steep walls and a depth of several hundred meters (Myers and others, 2002). The SE summit crater sometimes contains a crater lake and is considered Korovin’s active crater. ::: figure 5 is an aerial photo of Korovin, highlighting its two summit vents.

Figure 5. Photograph of Korovin volcano taken from an aircraft flying at 9.1 km altitude on 5 August 2007. The view is oblique and from the N (i.e. looking S). Steam is rising from the active crater (SE crater). The summit of Kliuchef volcano is partially visible at the top of the image; it sits ~5 km S of Korovin. Photograph taken by Burke Mees, Alaska Airlines. Photograph from McGimsey and others (2011).

During the summer of 2004, AVO installed a network of seismic stations throughout the northern part of Atka Island. Data from the network was accessible in March 2005; however, it wasn’t until December 2005 that Korovin was considered seismically monitored. On 2 December 2005, Korovin was also officially assigned the Level of Concern Color Code Green after “a sufficient period of background seismicity had been recorded” (McGimsey and others, 2007). Before, AVO had listed Korovin as UA (unassigned) during periods when no significant activity was noted. AVO assigns volcanoes UA when there is no real-time seismic network in the area that can be used to define background levels of seismicity.

In addition to being seismically monitored, Korovin is also monitored through ground-based, aerial, and satellite imagery and photographs. Korovin and its plumes are often photographed by residents of Atka village (::: figures 6 and 7), which are then sent to the AVO. ::: Figure 8 provides examples of photos of Korovin taken from satellites. Images from ::: figures 6-8 furnish various kinds of evidence, from steaming (i.e. non-eruptive cases, ::: figure 7), ash-bearing plumes (::: figure 6), and the result of ash-bearing eruptions (ash on the snow surface seen in satellite views, ::: figure 8). Evidence of these kinds is summarized in next section.

Figure 6. Photographs showing the progression of a steam plume that developed over Kovorin around 1900 on 23 February 2005. Plume was observed drifting to the E, and ash was seen falling out near the base of the plume. These photos were taken in Atka village and are courtesy of Louis and Kathleen Nevzoroff. Photos were taken from McGimsey and others (2008). Figure 7. Photograph of a steam column rising from Korovin on 27 July 2007. Steam was estimated to reach ~215-245 m above the crater. The photo was captured by Louis Nevzoroff from Atka village. Taken from McGimsey and others (2011). Figure 8. Two satellite photographs showing ash deposits on the upper E flank of Korovin in 2002 (top) and 2004 (bottom). The source of these ash deposits is thought to be intermittent, minor phreatic eruptions through the hot, roiling lake within the SE summit crater of Korovin (McGimsey and others, 2007). Top image was taken on 5 July 2002 and produced by the Image Analysis Laboratory, NASA Johnson Space Center. Bottom image was captured on 4 July 2004 and is an Ikonos near-infrared color composite, copyrighted by Space Imaging LLC. Both images originally published in McGimsey and others (2008).

Defining the term ‘eruption.’ There is no universally agreed-upon definition for the term ‘eruption’. McGimsey and others (2011) however, follow the GVP’s eruption definition where an eruption is an event involving explosive ejections of old or new fragmental material, the effusion of liquid lava, or both. Volcanically produced heat and near-surface water can interact explosively causing a dramatic eruption, which may or may not bring fresh volcanic material to the surface.

McGimsey and others (2011) go onto say, “The element of this definition we wish to emphasize are the verbs ‘eject’ and ‘effuse’ which refer to dynamic surface processes that pose some level of hazard. The presence or absence of often ambiguous ‘juvenile material’ or fresh magma is not relevant to this use of the term eruption, particularly when communicating a potential hazard that makes no distinction between juvenile and non-juvenile eruption products. This definition would not, however, include passive volcanic degassing or hydrothermal-fluid discharge unless accidental solid fragments are entrained.”

1998-2007 activity at Korovin. In this section of the Bulletin report, we summarize the volcanic activity at Korovin that took place between 1998 and 2007 (table 1). During this interval, activity ranged from eruptive cases to those that were considered non eruptive.

Activity was often reported to AVO by Atka village residents and pilots in the area. Korovin was also monitored through satellite imagery, when weather conditions were favorable. During this interval, the highest plumes were observed on 30 June 1998 and reached an altitude of ~9.1 km. As activity varied at Korovin, the Aviation Color Code (ACC), the Volcanic Activity Alert Level (VAAL), and the Level of Concern Color Code (LCCC) were changed to reflect Korovin’s activity status.

On their website, AVO presented general information on Korovin’s reported activity from 1998-2007. For each of the events within this interval, AVO cited information from several sources, some of which included the following: McGimsey and others (2003), which discussed activity in 1998; McGimsey and others (2008), which discussed 2005 activity; Neal and others (2009) that looked at 2006 activity; and McGimsey and others (2011) that detailed 2007 activity. AVO also referenced several past Bulletin reports, which highlighted Korovin activity (BGVN 23:06, and 31:02).

Our summary in table 1 summarizes the following: (1) the basic information on Korovin’s activity from the AVO website and (2) additional information from some of AVO’s cited references. Greater detail can be found on AVO’s website and in their cited references.

Table 1 contains two columns, entitled Date and Remarks. The Date column refers to the year of Korovin activity. The Remarks column generally contains the following: (1) “AVO:” This presents a very brief synopsis of the summary that AVO provides on each of their Korovin reported activity web pages (as accessed in May 2015). (2) Below that, we present a succinct timeline of Korovin activity created using on information found in some of AVO’s cited references.

In table 1, please note we have separated 2005 activity into two rows, to highlight two different periods of activity during that year. Also note that 2006-2007 is considered one period of activity and is therefore detailed in one section (i.e., one row).

Table 1. Table that condenses key events at Korovin during both eruptive and non-eruptive periods during 1987-2007. The data sources are stated in the table. Where AVO cited references are augmented by past Bulletin reports, the information has been [bracketed]. Times are all local, unless otherwise stated. The term ‘resident(s)’ refers to resident(s) of Atka village. Abbreviations used are as follows: Village Public Safety Officer, VPSO; above sea level, a.s.l., and Interferometric synthetic aperture radar, InSAR; Aviation Color Code, ACC; Volcanic Activity Alert Level, VAAL; Level of Concern Color Code, LCCC; unassigned activity (UA); and satellite-based Ozone Monitoring Instrument, OMI.

Date Remarks
1998

AVO:

Eruption started, 30 June 1998 ±1 month. Eruption end, 30 June 1998 ± 7 days

 

McGimsey and others (2003):

Eruption start / stop dates: 30 June / 8 July

“…, the timing of this activity remains poorly constrained; intermittent ash may, in fact, have occurred weeks or prior to June 30.”

10 May- Pilot observed ash on SE slope. Pilot had seen no ash the previous week and speculated the ash was deposited a few days prior to May 10

28 June-Individual reported a dark ash plume over Korovin

30 June-VPSO in Atka village reported two separate clouds, first at ~0730 and second at ~0830. Second cloud rose ~9.1 km and was tinted orange. VPSO said events “produced dustings of ash in Atka”. AVO received 2 pilot reports: (1) at 1115, noted volcanic cloud reached ~4.9 km a.s.l., (2) at 1720, cloud to 9.1 km near Korovin

2 July- Resident reported a ‘rusty’ cloud, ~4.9 km a.s.l. moving SE

3 July- Pilot reported profuse steam from summit crater and ash on S, SE and E flanks. Thin trail of ash extended SW towards Atka village

8 July- AVO noted minor, weakly ash-bearing clouds over Korovin with satellite images

2002 AVO:

Eruption started, July 2002 ±1 month. Considered a questionable eruption

 

McGimsey and others (2008):

5 July- Satellite photo of ash deposits on upper E flank of Korovin (::: figure 8 top). “Intermittent, minor phreatic eruptions through a hot, roiling lake in the south summit crater of Korovin [is] the probable source.”

2004 AVO:

Eruption started, June 2004 ±1 month. Considered a questionable eruption

 

McGimsey and others (2008):

4 July- Satellite photograph shows ash deposits on upper E flank of Korovin (::: figure 8 bottoms). Same explanation as 5 July 2002

 

Neal and others (2009):

7 July- Korovin photographed with ash covering the snow on its E flank. According to the caption of the photograph, “The deposit may be the result of phreatic explosions or vigorous wind remobilization of ash from within the summit crater.”

 

19 July- Aerial photograph of Korovin showing ash deposited around the crater vent. The caption for the photograph states, “At times, a shallow body of gray, turbid water partially fills the inner crater and, in 2004, was observed roiling. Phreatic explosions from this water-rich, high-temperature system may be responsible for the occasional localized ash-fall deposits seen on the upper flanks of Korovin.”

2005 AVO:

Eruption started, 23 February. Eruption end, 7 May ± 14 days. Considered a questionable eruption.

 

McGimsey and others (2008):

23 February- Clear day. Residents noted minor steaming around 1200. Around 1900, residents observed dark cloud rising several thousand feet and drifting E (::: figure 6). Ash seen falling out near base of plume. Minutes later, three or four smaller gray puffs seen. No other activity seen that night. In satellite imagery, small steam plume with minor ash noticed. Height of plume estimated at ~3 km (10, 000 ft)

24 February- LCCC was raised from UA (unassigned) to Yellow

4 March- LCCC reduced from Yellow to UA

19 March- Pilot report noted steam rising several thousand feet above Korovin

Early May- Observational data showed roiling lake in SE crater emptied. Visible glow.

2005 AVO:

Seismicity without confirmed eruption, start / end: 13 September

 

McGimsey and others (2008):

13 September- Long sequence of strong seismicity. Sequence began with two small local events, then ~30 minutes of weak tremor, and then ~20 weak local events. Nothing unusual noted in satellite images from this time.

2006-2007 AVO:

Non-eruptive activity started, 16 January 2006 and ended September 2007 ± 2 months.

 

Neal and others (2009):

16 January 2006- Background seismic activity increased

17-18, 21 Jan and 21-22 Feb- burst of tremor-like signals

22 February 2006- LCCC increased from Green to Yellow

Early March- Seismicity stabilized and then decreased

8 March- LCCC downgraded from Yellow to Green

July- Increased number of earthquakes in vicinity of Korovin

September and October- Increased tremor episodes

19 October- SE crater lake disappeared by this date and absent for rest of 2006. Lake present on 12 September (satellite data).

29 October- White vapor plumes rose several hundred meters above Korovin and coincided with ~5-min of strong tremor

5 November 2006- Strongest earthquake swarm recorded by seismic network

6 November- Yellow ACC and an Advisory VAAL declared

18 November- dark-gray ash on E flank of SE crater observed in ASTER satellite images. Ash was not present in image from 21 November. ASTER satellite imagery showed warm spots in Korovin crater

Late November 2006- Significant deformation in latter half of 2006. Circular pattern of uplift, as much as 5 cm noted through July and October InSAR data. November-December- Seismicity high; strong, short-lived signals. Low-frequency tremor bursts.

11, 21 and 24 December 2006- Residents photographed large, white-vapor plumes rising from Korovin. One resident noted that he saw ash falling below the plume he reported. Ash was not verified on the ground

End of 2006-No ash detected in atmosphere or on ground through satellite data. Rise in ground temperature also not detected

McGimsey and others (2011):

Beginning of 2007- ACC, Yellow, and VAAL, Advisory due to increased activity in 2006. High seismicity from 2006 continued into 2007. Inflation (uplift) in N part of Atka Island that began in June 2006 totaled 9-10 cm and began to taper off in 2007

11 January 2007- M3.5 earthquake considered large for volcano-generated seismicity.

23 January- Series of tremor bursts

24 January- Resident took pictures of steam column rising from SE crater and reported similar steam columns rose ~300 m every 15-80 minutes

14 February 2007- Pilot reported a steam plume extending 1.5-2.4 km over Korovin

3 March- Residents photograph ash deposit on W flank. Residents observed steam from SE summit vent. Flurry of low-frequency seismicity in morning

May, June & August- Episodes of tremor lasted several days

27 July 2007- Steam plumes observed by residents (::: figure 7)

5 August- OMI detected small SO2 cloud, 300 km N of Cleveland volcano. Based on wind dispersal models, cloud believed to be from Korovin. Aerial photo (::: figure 5) showed steam rising from SE crater

20 August- OMI detected small emission of SO2 from Korovin

7 September- ACC/VAAL downgraded to Green/Normal due to decreasing trends in seismicity and uplift

October-December 2007- uneventful

References. Alaska Volcano Observatory (AVO), 2014, Korovin Volcano description and information, accessed on 14 April 2015, (URL: http://www.avo.alaska.edu/volcanoes/volcinfo.php?volcname=Korovin)

Alaska Volcano Observatory (AVO), 2014, Korovin reported activity, accessed on 14 April 2015, (URL: http://www.avo.alaska.edu/volcanoes/volcact.php?volcname=Korovin)

Alaska Volcano Observatory, the U.S. Geological Survey, BigTopo 7, and AllTopo 7, Topographic shaded relief image of the northern part of Atka Island (Image 2906), accessed on 14 April 2005, (URL: http://www.avo.alaska.edu/images/image.php?id=2906)

McGimsey, R. G., Neal, C. A., and Girina, O., 2003, 1998 volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 03-0423, 35 pp, (URL: http://pubs.usgs.gov/of/2003/of03-423/)

McGimsey, R.G., Neal, C.A., Dixon, J.P., and Ushakov, S., 2008, 2005 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2007-5269, 94 pp, (URL: http://pubs.usgs.gov/sir/2007/5269/)

McGimsey, R.G., Neal, C.A., Dixon, J.P., Malik, N., and Chibisova, M., 2011, 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2010-5242, 110 pp, (URL: http://pubs.usgs.gov/sir/2010/5242/)

Myers, J.D., Marsh, B. D., Frost, C. D. and Linton, J.A., 2002, Petrologic constraints on the spatial distribution of crustal magma chambers, Atka Volcanic Center, central Aleutian arc, Contributions to Mineralogy and Petrology, vol. 143, issue 5, pp. 567-586, DOI 10.1007/s00410-002-0356-7 (URL: http://link.springer.com/article/10.1007/s00410-002-0356-7)

Neal, C.A., McGimsey, R.G., Dixon, J.P., Manevich, A., and Rybin, A., 2009, 2006 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2008-5214, 102 pp, (URL: http://pubs.usgs.gov/sir/2008/5214/ )

Simkin, T., and Siebert, L., 1994, Volcanoes of the World (2nd edition), Geoscience Press, 349 pp.

Siebert, L., Simkin, T., & Kimberly, P., 2010, Volcanoes of the World (3rd edition), University of California Press, 551 pp.

Information Contacts: Sakhalin Volcanic Eruptions Response Team (SVERT), Institute of Marine Geology and Geophysics (IMG&G) Far East Division Russian Academy of Sciences (FED RAS), 1B Science St., Yuzhno-Sakhalinsk, 693022, Russia (Email: rybin@imgg.ru, URL: http://www.imgg.ru/).

Geological Background


The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SE. Lava flows from a cone within the breached crater reached the north shore of the island. Historical eruptions have been recorded at Chirinkotan since the 18th century. Fresh lava flows also descended the SE flank of Chirinkotan during an eruption in the 1880s that was observed by the English fur trader Captain Snow.

Eruptive History


Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2013 Jun 11 2015 Apr 5 (continuing) Confirmed   Historical Observations
2004 Jul 20 2004 Jul 20 Confirmed 2 Historical Observations
1986 Oct 11 1986 Oct 12 Confirmed 1 Historical Observations
1979 Apr 1980 Oct 10 Confirmed 2 Historical Observations
1955 (?) Unknown Confirmed 2 Historical Observations Floor of summit explosion crater
1900 ± 10 years Unknown Confirmed   Historical Observations
1884 ± 6 years Unknown Confirmed 0 Historical Observations North foot of inner summit cone
[ 1760 (?) ] [ Unknown ] Uncertain 2  

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Synonyms

Tirinkotan | Chirinkutan | Cherinkutan

Photo Gallery


The small, mostly unvegetated 3-km-wide island of Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. Submarine terraces are lacking around the island, suggesting the edifice is of Holocene age. Chirinkotan lies at the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Historical eruptions have been recorded at Chirinkotan since the 18th century, including one observed by the English fur trader Captain Snow.

Photo by R. Bulgakov, 1990 (Institute of Marine Geology and Geophysics, Yuzhno-Sakhalin).

References


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Gorshkov G S, 1958. Kurile Islands. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 7: 1-99.

Gorshkov G S, 1970. Volcanism and the Upper Mantle; Investigations in the Kurile Island Arc. New York: Plenum Publishing Corp, 385 p.

Volcano Types

Stratovolcano
Caldera
Pyroclastic cone

Tectonic Setting

Subduction zone
Intermediate crust (15-25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Dacite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
0
0
0
6

Affiliated Databases

Large Eruptions of Chirinkotan Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.