VOLCANO: Bulletin of the Global Volcanism Network Volume 34, Number 7, July 2009

Kirsten Chojnicki <kchojnic@xxxxxxx> · Thu, 24 Sep 2009 15:42:36 -0700

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Bulletin of the Global Volcanism Network Volume 34, Number 7, July 2009
http://www.volcano.si.edu/
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Bulletin of the Global Volcanism Network
Volume 34, Number 7, July 2009
Tungurahua (Ecuador) Eruptions in 2008-2009; two fatalities in sudden flood on 22 August 2008
Galeras (Colombia) Explosions during February-June 2009, ashfall up to 180 km away
Uzon (Russia) Valley of Geysers two years after the major landslide of June 2007

Suwanose-jima (Japan) Explosive eruptions continue through 6 July 2009
Makian (Indonesia) Seismicity increased during May 2009 after tectonic earthquakes
Talang (Indonesia) Sudden occurrence of over 900 earthquakes on 16-17 August 2009

Sangeang Api (Indonesia) Increased seismicity, including explosion earthquakes, during May-June 2009
Rumble III (Kermadec islands) Submarine summit craters underwent collapse and eruption
Erta Ale (Ethiopia) Changes at NW and S pit craters between 2002 and 2009

Editors: Rick Wunderman, Edward Venzke, and Sally Kuhn Sennert
Volunteer Staff: Ludmila Eichelberger, Russell Ross, Paul Berger, Hugh Replogle, Robert Andrews, Catie Carter,
Margo Morell, Jacquelyn Gluck, and Stephen Bentley

Tungurahua
Ecuador
1.467°S, 78.442°W; summit elev. 5,023 m
All times are local (= UTC - 5 hours)
Our previous report on Ecuador's Tungurahua (BGVN 33:06) summarized the ongoing activity through mid-February 2008. This report covers February 2008-July 2009. The Instituto Geofisico-Escuela Politecnica Nacional (IG) has maintained a continuous watch on Tungurahua in order to provide immediate alert of significantly heightened activity to prevent as much damage to property and population as possible. Several pyroclastic flows occurred.

Steam and ash plumes have been continuous since early 2008. These plumes have generally risen to ~ 8-9 km with occasional higher plumes as a result of increased activity. Ashfalls were frequently associated with the steam, gas and ash emissions, and deposited small layers of the larger particles downwind, sometimes 8-11 km from the crater. On 1 March 2009, an explosion produced a significant plume that rose to an altitude of ~ 10 km and drifted NW. By 3 March, the ash on the volcano's W side covered at least 2.5 km^2 of cropland, and additional cattle-grazing pasture.

Ashfall accumulation (figure 1) was recorded for a time interval slightly before the current reporting interval, but the available later maps were similar. Towns affected on figure 1 included Choglontus, El Manzano, Palitahua, Cahuaji, Sabanag, Santa Fe de Galan, Penipe, and Bayushig. Lighter ashfall was also repeatedly noted in Riobamba and Guano.

Figure 1. Ashfall accumulated from Tungurahua eruptions during 30 January-10 February 2008. N is towards the top and the horizontal scale can be read from to the index marks on the map's margin, which are at 5-km intervals. The three isopachs shown represent thicknesses of 1, 2, and 3 mm (increasing thickness inward). Courtesy of IG.

On various occasions, incandescence and the ejection of large blocks were Strombolian in character. Roaring, explosions, and "cannon shot" noises were reported almost daily. On 4 August 2008 one explosion was heard as far away as Ambato, 31 km to the NW.

Lahars, floods, and two fatalities. Lahars or mudflows descended drainages to the NW, W, SW, and S repeatedly during the reporting period (many times per week). On 8 March 2008, lahars transported blocks up to 3 m in diameter; in many other cases the largest blocks were around 1 m in diameter. Lahars occasionally affected roads in the Pampas sector to the S and disrupted the access road to Banos.

On 21 August 2008, intense rains prompted the Volcanic Observatory of Tungurahua (OVT) to issue a warning of potential lahars in the Vascun river. A natural dam in that river had been previously identified as a potential hazard.

On 22 August, the dam ruptured and a flood descended. A bridge crossing the river on the outskirts of Banos endured the flooding but was overridden by ~ 20 cm above the railing (figure 2). The flood also destroyed two homes and the El Salado public pools, 1,700-1,800 m downstream of the dam (figure 3). Two people were reported injured and two were reported missing and presumably killed.

Figure 2. (left) A view of a bridge impacted by the Tungurahua flood and lahar of 22 August 2008. A vertical support appears damaged. (right) A smaller bridge showing high water mark about 1 m above the road. On the far bank is scouring near the base, and above that, fresh deposits, including some on  the guardrail. The lahar may have caused or contributed to damage on abutment and horizontal support beam, which appears battered and deformed. Courtesy of IG.

Figure 3. Three photos of the El Salado pool facility on the N flank of Tungurahua, where an August 2008 flash flood destroyed significant portions of the buildings and the retaining wall, and gravels swept as high as the roof of some buildings. (top) An overview of the ruined pool facility. (bottom) Measurements help convey the scale of the river's high stand and aftermath. IG authors also sketched a line showing the highest water level. Inset photo was taken when the pool was in use prior to the flood; the river is at right out of view. Courtesy of IG.

Lahars on 23 October again descended the Vascun river, causing a landslide and rupturing a water pipe that serviced Banos. On 1 November, lahars descended multiple drainages, carrying blocks up to 1 m in diameter to the SW. Residents bordering the Vascun river temporarily evacuated, but returned after the rain stopped.

Pyroclastic flows and explosive activity. Explosive activity continued through the reporting period, including pyroclastic flows. Noteworthy pyroclastic flows occurred on 29 May 2008, when they descended the N and NW flanks of Tungurahua, with deposits observed the next day. In July 2008, a pyroclastic flow was associated with significant ash and tephra fall (with grains up to ~ 3 mm in diameter) reported in the towns of Cahuaji, Chazo, Palestina, Santa Fe de Galan, and Guaranda.

Explosions often ejected incandescent blocks that rolled downslope; on 21 June 2009, lava fountains that rose to a height of 500 m above the crater expelled incandescent blocks that were later discovered as far as 2 km downslope. Notable pyroclastic flows, explosions, as well as some lahars and ash plumes were reported (tables 1 and 2).

Table 1. Tungurahua behavior during 19 February-30 December 2008. Only selected examples of near-daily lahars are shown. A map and table of Tungurahua's drainages (quebradas) and surrounding towns appeared previously (BVGN 29:01); locations  mentioned  include the Mapayacu and Choglontus drainages to the SW; the Pampas sector to the S; Cusua, 7 km to the NW; Manzano, 8 km to the SW; and the particularly vulnerable city of Banos, 8 km to the N. Courtesy of IG.

   Date (2008)         Observations
   19, 20, 25 Feb      Lahars affected roads in Pampas sector
   06 and 08 Mar       Lahars descended W and S drainages; some carried blocks up to 3 m
                         in diameter
   25 Mar              Explosions; incandescent blocks from summit fell on flanks

   09, 12, 13 Apr      Lahars and mudflows on S and NW drainages that disrupted the access
                         road to Banos
   21 Apr              A lahar disrupted the Ambato-Banos road for a few hours
   23 Apr              Blocks rolled 600 m down the flanks

   01 May              Explosions and intense summit incandescence; windows vibrated in areas
                         6 km NE
   11 May              Blocks rolled ~ 1 km down the flanks
   12 May              Explosion; rockfalls occurred in an area 8 km to the S

   17-18 May           Explosion similar to that on 12 May; windows rattled in areas to the
                         SW and W
   19 May              Large explosion; numerous incandescent blocks rolled ~ 1.6 km down

                         the flanks
   22, 25-27 May       Windows vibrated in nearby areas, including at the observatory (OVT)
                         in Guadalupe
   23 May              Marked increase in explosions, ash plumes, and ashfall; summit

                         incandescence at night
   29 May              Pyroclastic flows descended the N and NW flanks, with deposits
                         observed the next day
   15 Jun              Lahars descended the NW and S drainages and resulted in a road closure

                         to the S
   19 Jun              Blocks ejected 500 m above the summit and rolled ~ 1 km down the flanks
   20 Jun              Mudflow to the SW towards the Puela river carried blocks up to 80 cm

                         in diameter
   31 Jul, 3-4 Aug     Blocks rolled ~ 1 km downslope; ashfall to SW and W; an explosion on
                         the 4th,
   19-22 Sep           Small mudflows in the W and NW; a lahar 50 cm thick to the S

   23 Oct              Muddy waters caused a landslide and a ruptured water pipe that serviced
                         Banos
   01 Nov              Lahars carried blocks ~ 50-70 cm in diameter in Juive, La Pampas,

                         and Bilbao
   04 Nov              Light ashfall was reported in Pallate and part of Riobamba
   15 Dec              A ash column rose to ~ 1 km
   15-24 Dec           Ash columns reached a height of ~ 6 km

   17, 21-23 Dec       Ejecta visible from Guadalupe Observatory
   23 Dec              Incandescent material rolled down flanks
   24 Dec              Small pyroclastic flow on NW flank; incandescent lava flowed down one

                         of the flanks
   25-26, 28-30 Dec    Blocks rolled 500 m downslope on 25 Dec, 1,500 m on 29 Dec, and 800 m
                         on 30 Dec; heavy black ash fell in areas to the SW
Table 2. Tungurahua behavior during 2 January-7 July 2009. Only selected examples of near-daily lahars are shown. Courtesy of IG.
   Date (2009)         Observations
   02-04 Jan           Blocks rolled ~ 800 m down the flanks; Strombolian activity on 4 Jan
   07, 10 Jan          Incandescent blocks rolled down flanks
   08 Jan              Continuing gas-and-vapor emission; ash columns less than 2 km high

                         drifted W, NW, SW, and NE. Ashfall in El Manzano, Choglontus,
                         Palictahu and Cahuaji
   16 Feb              Ash emissions that generated a plume with altitude of ~ 8 km and

                         drifted W
   01 Mar              Ash plume that rose to an altitude of ~ 10 km and drifted NW
   03 Mar              Ashfall covering at least 2.5 km2 of cropland and additional
                         cattle-grazing pasture

   21 Mar              Lahars carried blocks up to 30 cm in diameter to the SW
   26 Mar              Lahar in the Mapayacu drainage carried blocks up to 2 m in diameter
   06 Apr              Fumarolic plumes rose 500-600 m; light ashfall reported 8 km SW

   14 Apr              A steam-and-gas plume containing some ash rose to an altitude of
                         ~ 7.5 km and drifted N
   22 Apr              Incandescent blocks ejected from the crater and rolled down flanks

   06 May              Ashfall reported in Banos, ~ 8 km to the N
   13, 18 May          A fine layer of ash fell in Manzano, 8 km to the SW
   24-26 May           Incandescence from the crater seen and blocks rolled 100-500 m down

                         the flanks
   27 May-02 Jun       Strombolian activity
   21 Jun              Lava fountains rising to a height of 500 m above the crater
   02, 5-7 Jul         Lahars descended SW and W drainages carrying blocks up to 40 cm

                         in diameter
Geologic Summary. Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major volcanic edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the W, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Banos at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.

Information Contacts: Geophysical Institute (IG), Escuela Politecnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/).

Galeras
Colombia
1.22°N, 77.37°W; summit elev. 4,276 m
All times are local (= UTC - 5 hours)
Activity during 1 September to 16 December 2008 (BGVN 33:11) included modest seismicity, tremor, plumes, moderate sulfur-dioxide (SO2) emissions, and incandescence from the main crater and lava dome. This report describes activity chronicled by the Instituto Colombiano de Geologia y Mineria (INGEOMINAS) for 17 December 2008-31 July 2009.

This interval included explosive eruptions on 14 and 20 February, 13 March, 24 and 29 April, and 7 and 8 June. Some plumes rose to about 10-14 km altitude (the highest on 8 June) and carried significant ash. Seismicity on or near the volcano suggested fluid movements at depth.

On their website, INGEOMINAS provides comprehensive reports covering half-year intervals (starting in 2004). The latest available discusses the first half of 2008.
Mentioned in the latter report are more details on a large volcanic bomb from the 17 January 2008 eruption, which left a 15-m-diameter crater near the summit (BGVN 33:03). Field workers found only angular fragments of the original bomb in the impact crater (pieces often under 1 m in diameter)-but they estimated that the original bomb was on the order of 5 m in diameter. Photos of the downslope areas detected smaller impact craters thought to have been created by fragments that bounced out beyond the large crater. The same report also features isopach maps and discussion of grain size distributions for the 17 January 2008 eruption. That eruption emitted 870,000 m^3 of material, which was dispersed up to 71 km W.

INGEOMINAS reported that the 14 February explosion was preceded by minor plumes (reaching 300-500 m above the crater rim) on 8 and 9 February. On 10 February, SO2 fluxes were 1,040-4,300 metric tons/day. The explosive eruption began at 1910 on 14 February. An accompanying shock wave was detected in multiple areas, including Pasto, a city about ~ 10 km E. Cloud cover prevented observations of the ash plume. From about 1930 until 2030, observers noted ashfall, rain, and an odor of sulfurous gas on the volcano's slopes as well as in Pasto. Ash fell mainly to the E and as far away as 25 km. The Alert Level was raised from III (Yellow; "changes in the behavior of volcanic activity") to I (Red; "imminent eruption or in progress"). The local hazards scale ranges from from IV (low) to I (high).

At 1950 seismicity dropped to levels similar to those recorded before the eruption. On 16 February, the Alert Level was lowered to II (Orange; "probable eruption within days or weeks"). During 16-17 February, small steam plumes rose to altitudes of 4.6-6.7 km and drifted SE, E, and NE. According to news accounts (Agence France-Presse, Caracol Radio), authorities ordered the evacuation of about 8,000 people on the slopes, but few went to shelters.

The explosion at 0705 on 20 February prompted authorities to raise the Alert Level back to I (Red). The 13-minute-long signals represented roughly double the seismic energy seen on the 14th. Shock waves were felt in several local communities. Associated sounds were heard in Popayan (~ 160 km NNE). Observers on the E flank reported two explosions, incandescent blocks ejected above the summit, ash emissions, and a sulfurous odor. Ashfall was reported to the W. Gas plumes with a low ash content continued, especially in the afternoon, reaching 700 m above the summit.

Although INGEOMINAS reported that the 20 February ash plume rose to 8 km altitude, analysis by the Washington Volcanic Ash Advisory Center (VAAC) yielded both a higher plume and variable displacements with altitude. The VAAC analysts, promptly notified by INGEOMINAS, compared plume motion seen on GOES-13 satellite imagery and winds from GFS (the Global Forecast System, a numerical weather prediction computer model run four times per day by NOAA). This enabled them to establish the plume's behavior with altitude. The resulting work indicated some of the ash rose as high as 12.5 km.

The VAAC's Ash Advisory of 20 February issued at 0835 local time was as follows: "INGEOMINAS reported an explosive eruption of Galeras at 1204 [UTC; 0704 local time]. Ash at FL410 [41,000 feet; 12.5 km altitude] was moving towards the E at 30 kts [knots, equivalent to 56 km/hour] while ash at FL220 [6.7 km altitude] was moving towards the W at 15-25 kts [28-46 km/hour]. Ash between these layers was moving N at 25 kts [46 km/hour]."

A Volcanic Ash Advisory issued on 20 February at 0854 local time noted "Ash to FL410 is quickly becoming diffuse as it races E while ash to FL280 remains identifiable moving towards the NW at 1315[UTC]." The next Advisory, at 1450 local time, noted ash had dissipated and no new eruptions were reported.

INGEOMINAS stated that the eruptions of 14 and 20 February released an estimated minimum volume of 2 x 10^6 m^3 of tephra. This was ~ 40% of the lava dome's volume. On 20 February, the SO2 was estimated at 100-800 tons/day. A few days later the values stood below 430 tons/day.

The Alert Level was lowered on 21 February and again on 3 March (to Level III). During 22 February to 10 March, occasional white gas plumes with variable ash content rose to a peak altitude of less than 6.3 km.

On 13 March, another explosive eruption occurred. Bad weather prevented direct observations, but the Washington VAAC noted a plume rising to an altitude of ~ 12.3 km drifting NW. The eruption produced sounds heard 10 km E and W. Ashfall was reported in multiple areas E and NW; a sulfur odor was also reported in some areas. Gas plumes with some ash rose on 14 March to an altitude of 6.3 km.

According to a news account in El Tiempo, authorities again ordered the evacuation of about 8,000 people living in high-risk areas, but as before this order was generally ignored. Soon after, the Alert Level was lowered to back to II. On 24 March, the Alert Level was lowered again to III. During the week ending around 24 March, daily SO2 levels were high. Earthquake levels were low in both intensity and occurrence. During 21-23 March, white-colored gas plumes rose to an altitude of 5.4 km and drifted in multiple directions.

On 3-7 April, pulsating gas plumes, sometimes containing ash, were seen when visibility was good. The plumes rose to altitudes less than ~ 6 km. Overflights on 5, 6, and 7 April revealed emissions from different areas in the main crater. On 7 April some of the higher temperature zones were 180°C, and an incandescent area measured 500°C.

Another explosive eruption occurred on 24 April. Incandescent blocks caused fires on the N flank. An accompanying shock wave was reported by residents up to 25 km away. A second eruption, longer but weaker than the first, was detected about 30 minutes later. Incandescence from both eruptions was seen from the city of Pasto. An ash plume rose to an altitude of ~ 10.3 km and ashfall was reported in areas up to 20 km W, WNW, and NW.

On 25 April, ash-and-gas plumes rose 1 km above the crater. Thermal anomalies in the crater near the W flank measured 100°C. Ejected rocks landed 2-3 km from the crater. According to a news article in Colombia Reports, residents living near the volcano were again ordered to evacuate; about 200 people responded. The Alert Level was lowered to II. Several days later, on 29 April, another eruption occurred. Observers reported that an ash plume drifted NW and ash fell in areas up to 35 km downwind.

During 4-5 May, ash plumes drifted NE and ashfall was reported in multiple areas of Pasto. On 6 May, gas-and-ash plumes rose to an altitude of 5.8 km and drifted NE. An overflight revealed incandescence from a vent 90-100 m in diameter in the main crater that had a temperature of 500°C. White plumes originated from multiple points inside and outside of the crater. The Alert Level was lowered to III.

On 9 May, an M 2.2 volcano-tectonic earthquake occurred 6 km to the NE of the main crater at a depth of ~ 10 km. On 11 May, seismicity increased, and hybrid earthquakes and tremor were detected. The seismicity, along with incandescence in the crater and low SO2 values, led INGEOMINAS to conclude that the volcano might have become overpressurized.

During 12-19 May Galeras emitted gas plumes, occasionally containing some ash. An overflight on 17 May revealed gas emissions from multiple points inside and outside the main crater. Some thermal anomalies surpassed 180°C. During 17-18 May, two M 2.9 earthquakes occurred 6 km SSE at depths of 2-3 km, and on 18 May an M 2.3 earthquake occurred at a depth of 3-5 km, 5 km SSW.

On 7 June, an eruption occurred that was preceded by a M 4 earthquake located about 3 km SSE of the crater at a depth of 2 km. Vibrations from an accompanying acoustic wave were detected by residents. The eruption produced an ash plume that rose to an altitude of 6.8 km and drifted NW; ashfall was reported downwind.

On 8 June, two explosions about 5 minutes apart were heard up to 45 km away. The event was preceded by an M 3.9 earthquake centered 1 km E at a depth near 2 km. Ashfall was reported the NW, up to 180 km away. Based on analysis of satellite imagery, the Washington VAAC reported that the ash plume rose to an altitude of 10 km and drifted NW. A second larger eruption produced an ash plume that rose to an altitude of 13.7 km and drifted SE.

Activity declined in the next few weeks. On 9 June, INGEOMINAS reported that seismicity and sulfur dioxide output were low, and that clear conditions revealed no emissions. On 10 June, INGEOMINAS lowered the Alert Level to II. Pulsating steam plumes rose from the crater and drifted NW.

On 19 June, INGEOMINAS lowered the Alert Level to III, based on increased SO2 degassing and seismicity (related to fluid movement) that seemingly resulted in the overall lowering of pressure in the volcanic system. Around this time, scientists on a monitoring flight saw gas emissions near the crater rim and recorded a thermal anomaly within the main crater. Gas plumes with some ash rose from Galeras on 22-23 June. An overflight on 23 June revealed that temperatures in the main crater measured 60° to 120°C, except for a small 220°C zone. Gas emissions originated from the periphery of the main crater. On 26 June, seismicity similar to that seen during previous eruptions, along with low rates of gas emissions, prompted INGEOMINAS to raise the Alert Level to II.

The last thermal anomalies at Galeras recorded from satellite by the MODVOLC system was on 4 December 2008. No alerts were recorded during 17 December 2008-31 July 2009.
Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the Wand left a large horseshoe-shaped caldera, inside which the modern cone has been constructed. Major explosive eruptions since the mid-Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone whose summit lies slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.

Information Contacts: Instituto Colombiano de Geologia y Mineria (INGEOMINAS), Observatorio Vulcanologico y Sismologico de Popayan, Popayan, Colombia (Email: uop@xxxxxxxxxxxx); Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: ttp://hotspot.higp.hawaii.edu/); Agence France-Presse (URL: http://www.afp.com/afpcom/en); Caracol Radio (URL: http://www.caracol.com.co/); El Tiempo (URL: http://www.eltiempo.com/).

Uzon
Kamchatka Peninsula, Russia
54.50°N, 159.97°E; summit elev. 1,617 m
Our previous report on the Valley of Geysers (BGVN 32:07) discussed a major landslide on 3 June 2007 that seriously damaged the landscape and destroyed several beautiful geysers. Scientists again visited the area about two years after the landslide. One of the geysers that was a few meters underwater returned to life after the confining lake waters dropped below the geyser's rim.

The following report came chiefly from Vladimir L. Leonov and his son, A.V. Leonov, who wrote an informal description of events (Leonov, 2008). The S-trending Valley of Geysers cuts radially across the topographic margin of the Geysernaya caldera at the SE end of the Uzon-Geysernaya caldera complex (figure 4).

Figure 4. A relief map showing a portion of Kamchatka's Eastern volcanic front near Uzon. The various calderas are surrounded by thick ignimbrite sheets. Uzon caldera sits to the W of and alongside the neighboring Geysernaia (Geysernaya) caldera to the E. The Geysernaya caldera is cut across its SE margin by the Valley of Geysers, a famous hydrothermal field. The field was partly buried in 2007 by a landslide that dammed the river descending the Valley (Geysernaya River, BGVN 32:07). In contrast to Uzon's flat floor, Geysernaya caldera contains abundant (dominantly Pleistocene) lava domes. This map was created by the Shuttle Radar Topography Mission (SRTM) and released by NASA/JPL/NIMA.

As previously reported, the landslide created a dam on the Geysernaya River, forming a lake. According to Leonov (2008), the lake surface rose to a maximum elevation of 435 m on 7 June 2007, before eroding, causing a rapid decline in water level to 426 m elevation.

During July and August 2007, the Emergency and Disaster Relief Ministry and volunteers deepened the new bed of the Geysernaya River by hand to lower the lake level by another 2 m, thus freeing the Bolshoi geyser vent from the cover of lake water. After these efforts, on 19 September 2007, the Bolshoi geyser revived and erupted for the first time since the 2007 landslide.

When studied in October 2008, the Bolshoi geyser (figure 5) responded to minor fluctuations of the water level in the lake. Bolshoi was seen to operate in either the regime of a geyser or in the regime of a pulsating source. When the water was low, the geyser regime was seen. With the rise of water of only about 10-15 cm (as a result rains or the melting of snow ) the water began to pour out of Bolshoi's vent in episodic pulsations.

Figure 5. The Bolshoi geyser after the lake's water level had decreased 11 m from the maximum level seen earlier. The basin (vent area) of the geyser is still slightly submerged but the rim is in places out of the water. Copyrighted photo from September 2007; courtesy of Milkovo.

The thickest section of landslide completely covered the 30-m waterfall at Vodopadny Creek (a branch of the Geysernaya River), and the geysers Troynoi (Triple), Sakharny (Sugary), and Sosed (Neighbor) (figures 6 and 7).

Figure 6. (right) Annotated aerial photo of the middle part of the landslide along the Geysernaya River looking NE as taken by Dmitry Zadirey (Kamchatka Airlines) on 5 June 2007. The landslide flowed from upper right towards lower left. Features are as follows: a) landslide-dammed lake; b) the dam; c) the site of buried waterfall along Vodopadny Creek; d) the buried geysers Triple, Sugary, and Neighbor; e) the Gate into the Valley of Geysers (also shown in figure 7). (left) Pre-landslide view of the the waterfall along Vodopadny Creek (copyrighted photo by Igor Katkov, 2004). From Leonov (2008).

Figure 7. The Gate into Valley of Geysers (left) seen before the landslide with steep canyon walls (copyrighted photo by Igor Katkov, 2004) and (right) the area after burial by the landslide (photo by Vladimir Leonov, October 2008). From Leonov (2008).

Geologic summary. The twin Uzon and Geysernaya calderas, containing Kamchatka's largest geothermal area, form a 7 x 18 km depression that originated during multiple eruptions during the mid-Pleistocene. Widespread ignimbrite deposits associated with caldera formation have a volume of 20-25 cu km (exclusive of airfall deposits) and cover an area of 1,700 sq km. Post-caldera activity was largely Pleistocene in age and consisted of the extrusion of small silicic lava domes and flows and maar formation in the Geysernaya caldera. The Lake Dalny maar in the NE part of the 9 x 12 km western caldera, Uzon, is early Holocene in age, and several Holocene phreatic eruptions have been documented in the Geysernaya caldera. The extensive high-temperature hydrothermal system includes the many hot springs, mudpots, and geysers of the Valley of Geysers, a 4-km-long canyon on the SE margin of the Uzon-Geysernaya caldera complex.

Reference. Leonov, A.V., 2008, Valley of Geysers 500 days later; (URL: http://spanishflyer.livejournal.com/39861.html); accessed on 6 July 2009.
Information Contacts: Vladimir L. Leonov, Institute of Volcanology and Seismology FED RAS, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/; http://www.kscnet.ru/ivs/kvert/current/klch/index.html ); Milkovo (URL: http://www.milkovo.ru/); Dmitry Zadirey, Air Company Kamchatka Airlines, Yelizovo, Russia.

Suwanose-jima
Ryukyu Islands, Japan
29.635°N, 129.716°E; summit elev. 799 m
All times are local (= UTC + 9 hours)
This small uninhabited island, one of Japan's most active volcanoes, lies ~ 175 km SSW of Kyushu Island. Previous reports on Suwanose-jima (BVGN 30:07, 32:11, 33:02, and 33:09) listed ash plumes between 28 April 2004 and 26 October 2008. This report continues the compilation through 6 July 2009 (table 3). Ash plumes were consistent and minor, below ~ 2.5 km altitude.

Table 3. A summary of Tokyo Volcanic Ash Advisory Center (VAAC) reports on explosive events and ash plumes from Suwanose-jima, 29 October 2008 to 6 July 2009. For some events, observers detected an explosion but were unable to observe a plume (NR indicates not reported). Courtesy of Tokyo VAAC, based on information from the Japanese Meteorological Agency (JMA), pilot reports, and satellite imagery.

   Date (UTC)               Plume altitude                Drift direction
   29-30 Oct 2008           1.5-1.8 km                    E
   31 Oct-01 Nov 2008       Explosions, plume data NR
   03 Nov 2008              1.5-1.8 km                    E
   05 Nov 2008              1.5 km                        NE

   07 Nov-08 Nov 2008       1.2-1.8 km                    E
   12 Nov-16 Nov 2008       Explosions, plume data NR
   13 Nov-15 Nov 2008       1.5-2.1 km                    --
   21 Nov 2008              1.5 km                        E

   25 Nov 2008              Explosions, plume data NR
   10 Dec-12 Dec 2008       0.9-1.8 km                    E
   14 Dec-17 Dec 2008       0.9-1.8 km                    E
   19 Dec-20 Dec 2008       1.5 km                        E (17, 19 Dec)

   26 Dec-28 Dec 2008       1.5-1.8 km                    --
   30 Dec 2008              Explosions, plume data NR
   03 Jan 2009              1.2 km                        E
   09 Jan 2009              Explosion, plume data NR

   21 Jan 2009              Explosion, plume data NR
   18 Feb-21 Feb 2009       Explosions, plume data NR (colored plume on 18 Feb rose 400 m)
   26 Feb-02 Mar 2009       1.2-1.5 km                    E (1 Mar)

   03 Mar 2009              Explosion, plume data NR
   06 Mar 2009              Explosions, plume data NR
   15 Mar-16 Mar 2009       1.5 km                        E (15 Mar)
   28, 30 Mar 2009          Explosion, plume data NR

   06, 8, 10 Apr 2009       Explosions, plume data NR
   21 Apr 2009              Explosion, plume data NR
   22 Apr-23 Apr 2009       1.2-1.5 km                    E, S
   27 Apr 2009              Explosion, plume data NR

   28 Apr-01 May 2009       1.5-1.8 km                    E, W
   07-09, 12-13 May 2009    Explosions, plume data NR
   17 May 2009              2.1 km                        --
   25 May 2009              1.5 km                        --

   16 Jun 2009              Explosion, plume data NR
   06 Jul 2009              Explosion, plume data NR
Yukio Hayakawa passed along quantitative data on the explosive eruption on 18 February 2009. The maximum amplitude of ground velocity computed from the analog data was expressed in units of 10^-5 m/s (in Japan this unit is expressed as mkine). The values on the 18th were 5.38 x 10^-5 m/s; and the airwave was 11 Pa. Hayakawa also indicated that the two explosive eruptions on 20 February had maximum amplitudes of 4.31 x 10^-5 m/s and 5.76 x 10^-5 m/s, respectively. The airwaves recorded were 20 and 18 Pa, respectively at microphones.

A visible-wavelength image from MODIS captured a small Suwanose-jima plume on 5 July 2009 (figure 8). As of mid-2009, no thermal alerts had been recorded by MODVOLC since 22 September 2008. The island is often covered by clouds, thwarting detection.

Figure 8. Image of Suwanose-jima taken on 5 July 2009 by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite. A beige-colored plume fans out and remains conspicuous for ~ 18 km to the NE blowing toward the island of Yaku-shima. Courtesy of NASA Earth Observatory and the US Air Force Weather Agency.

Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from On-take (Otake), the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of On-take collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884.

Information Contacts: Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); U.S. Air Force Weather Agency (AFWA)/XOGM, Offutt Air Force Base, NE 68113, USA; Hawai'i Institute of Geophysics and Planetology (HIGP) 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/).

Makian
Halmahera, Indonesia
0.32°N, 127.40°E; summit elev. 1,357 m
Makian remained in repose as tectonic earthquakes striking the region preceded a cluster of volcanic earthquakes during May and early June 2009. Makian lies SW of the S-central portion of Halmahera Island (in the province of Maluku Utara). Some local residents refer to the island as Mt. Kie Besi; however, it is better known under the name of Mt. Makian (other variants include Kie Besi, Makjan, Makyan, and Wakiong).

The last eruption of Makian occurred in 1988 (SEAN 13:07, 13:08, 13:10, and 13:11) and created a volcanic dome or plug on the crater floor with a diameter of 600 m and volume of ~ 282,600 m^3. The 1988 eruption led to the temporary evacuation of the island's 15,000 residents (SEAN 13:07). Not previously discussed in the Bulletin, the TOMS image archive shows several SO2 clouds from the 1988 eruption (during 30 July-5 August 1988) as well as visible and infrared imagery (Sawada, 1994).

The following information was translated from a Center of Volcanology and Geological Hazard Mitigation (CVGHM) report dated 17 July 2009. Authorities raised the hazard status on 2 June 2009 (from normal, Alert Level 1 to 2) due to the following seismic and other observations.

The pattern of earthquakes and tremor, high for most of May 2009, decreased rapidly after the 28th (table 4). Hot explosions continued until at least mid-June from sulfurous vents on the S side of the lava dome. Emissions from these vents were off-white, with weak pressure, and they fed a plume reaching ~ 10 m above the peak.

Table 4. Seismicity recorded at Makian during 1 May-3 June 2009. Courtesy of Center of Volcanology and Geological Hazard Mitigation (CVGHM).
   Date               Deep volcanic      Shallow volcanic    Maximum tremor
                       earthquakes         earthquakes         amplitude
   01-28 May 2009     43 (2/day avg.)    18 (1/day avg.)     0.5-1 mm
   29-31 May 2009     7 (2/day avg.)     13 (4/day avg.)     0.5-8 mm
   01 June 2009       1                  1                   0.5-6 mm

   02-03 June 2009    1-10/day           1-4/day             --
An increase in tectonic earthquakes in the Maluku Utara (N Moluccas) region preceded the increased activity at Makian. No recent morphological changes have been observed. Based on observations up to 30 June 2009, the hazard status was downgraded to Alert Level 1 on 16 July. However, authorities still prohibited people from climbing to the peak.

The MODVOLC system had no recorded thermal alerts from Makian from at least the beginning of 2000 through August 2009.
Geologic Summary. Makian volcano forms a 10-km-wide island near the S end of a chain of volcanic islands off the W coast of Halmahera and has been the source of infrequent, but violent eruptions that have devastated villages on the island. The large 1.5-km-wide summit crater, containing a small lake on the NE side, gives the 1,357-m-high peak a flat-topped profile. Two prominent valleys extend to the coast from the summit crater on the N and E sides. Four parasitic cones are found on the western flanks. Eruptions have been recorded since about 1550; major eruptions in 1646, 1760-61, 1861-62, 1890, and 1988 caused extensive damage and many fatalities.

Reference: Sawada, Y, 1994, Tracking of Regional Volcanic Ash Clouds by Geostationary Meteorological Satellite, in Volcanic Ash and Aviation Safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety, edited by Thomas J. Casadevall, U.S. Geological Survey Bulletin 2047.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) 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/).

Talang
Sumatra, Indonesia
0.978°S, 100.679°E; summit elev. 2,597 m
All times are local (= UTC + 7 hours)
Talang had an increase in seismicity during mid-2009. Minor tremor and emissions of ash and sulfur dioxide (SO2) occurred during 2007 (BGVN 33:02). The Alert Level was lowered to 2 (on a scale of 1-4) on 14 December 2007 based on visual observations and a decrease in earthquakes.

In their report of 17 August the Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported seismic activity between 1430 on 16 August through 0600 on 17 August. On 15 August there were four deep volcanic events and one low-frequency earthquake. Over the next two days they recorded 917 deep volcanic and another 30 shallow volcanic earthquakes, along with continuous tremor. Because of the significant increase in seismic activity, CVGHM increased the Alert Level from 2 to 3. It also stepped up its monitoring and assigned an emergency response team to conduct an onsite evaluation. Foggy conditions prevented visual observations. Visitors and tourists were advised not to go within 3-km of the summit.

Geologic Summary. Talang, which forms a twin volcano with the extinct Pasar Arbaa volcano, lies ESE of the major city of Padang and rises NW of Dibawah Lake. Talang has two crater lakes on its flanks; the largest of these is 1 x 2 km wide Danau Talang. Most historical eruptions have not occurred from the summit of the volcano, which lacks a crater. Historical eruptions from Gunung Talang volcano have mostly involved small-to-moderate explosive activity first documented in the 19th century that originated from a series of small craters in a valley on the upper NE flank.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/).

Sangeang Api
Lesser Sunda Islands, Indonesia
8.20°S, 119.07°E; summit elev. 1,949 m
According to the Center of Volcanology and Geological Hazard Mitigation (CVGHM), restlessness began at Sangeang Api in May and June 2009. In early May 2009 white emissions reached heights of ~ 5-25 m. In addition, occasional explosion earthquakes and generally minor seismicity continued (table 5). In addition, an earthquake struck on 1-2 June 2009 that was felt at a Modified Mercali intensity of MM I.

Table 5. Summary of reported volcanic activity at Sangeang Api. Courtesy of the Center of Volcanology and Geological Hazard Mitigation (CVGHM).
   Date               Explosions      Tremor and          Deep volcanic    Shallow volcanic
                                      amplitude           earthquakes      earthquakes
   01-17 May 2009     Avg. ~ 3/day    continuous, 3 mm    Avg. ~ 2/day     ~ 1/day
   18-31 May 2009     ~ 13/day        continuous,7 mm     ~ 4/day          ~ 2/day
   01-02 June 2009    ~ 21/day        continuous, 5 mm    ~ 2/day          1/day

   03 June 2009       11              continuous, 6 mm    7                --
On 4 June the Alert Level was raised to 2 (on a scale of 1-4) due to the increases in the number of explosion earthquakes, tremor, and other local earthquakes. Residents and visitors were prohibited from climbing the volcano. No thermal anomalies have been seen in MODIS imagery between 1999 and August 2009.

Geologic Summary. Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, 1,949-m-high Doro Api and 1,795-m-high Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the S side of Doro Mantoi and near the N coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/).

Rumble III
Southern Kermadec Arc, New Zealand
35.745°S, 178.478°E; summit elev. -220 m
GNS Science in New Zealand issued a press release on 12 March 2009 reporting that scientists have returned from exploring submarine volcanoes in the Kermadec arc, where they found evidence of a recent large eruption at Rumble III (figure 9). While mapping the volcano aboard the University of Washington research vessel Thomas G. Thompson on 11 March 2009, they found that marked changes had occurred in the bathymetry of the summits and ash deposits there since their previous visit in 2007. The base of the volcano sits at a depth of 1.4 km.

Figure 9. Map showing the location of Rumble III and other submarine volcanoes along the southern Kermadec arc. Rumble III volcano is located ~ 350 km NE of the Bay of Plenty, New Zealand, and is one of a number of submarine volcanoes that delineate the active arc front in this region. Courtesy of GNS Science (12 March 2009 press release).

A 2007 bathymetric map prepared by GNS Science showed an 800-m-wide crater near the top of Rumble III. The map, made aboard the RV Thompson in 2009, showed that this crater has been in-filled and a nearby summit cone had been reduced in height by ~ 100 m. "This suggests there has been a major eruption that collapsed the summit cone and filled the adjacent crater," said Co-Chief Scientist on the voyage, Cornel de Ronde of GNS Science. He also stated that the date of collapse was not known.

According to the same report, images taken by a WHOI underwater camera towed by the research ship showed strewn lava boulders covered by black volcanic ash near the summit. Consistent with the lowering of the summit, de Ronde noted that hydrothermal plumes emanating from the summit vents were more vigorous than observed previously. In addition, some new and deeper vents were discovered.

Olivier Hyvernaud looked for acoustic (T-wave) signals recorded by the French Polynesian network that may have originated from Rumble III. He reported that the Laboratoire de Geophysique in Tahiti did not see any acoustic events from that location.

Geologic Summary. The Rumble III seamount, the largest of the Rumbles group of submarine volcanos along the southern Kermadec arc, rises 2,300 m from the sea floor to within about 200 m of the sea surface. Collapse of the edifice produced a horseshoe-shaped caldera breached to the W and a large debris-avalanche deposit. Fresh-looking andesitic rocks have been dredged from the summit of Rumble III and basaltic lava from its flanks. Rumble III has been the source of several submarine eruptions detected by hydrophone signals. Early surveys placed its depth at 117 m, and later depths of about 200 m, 140 m, and 220 m were determined.

Information Contacts: GNS Science, Wairakei Research Centre, Private Bag 2000, Taupo 3352, New Zealand (URL: http://www.gns.cri.nz/research/marine/curtis_island.html); Cornel de Ronde, GNS Science (URL: http://www.gns.cri.nz/; Email: Cornel.deRonde@xxxxxxxxxx); Olivier Hyvernaud, Laboratoire de Geophysique, Commissariat a l'Energie Atomique (CEA/DASE/LDG), PO Box 640, Papeete, Tahiti, French Polynesia (Email: hyvernaud@xxxxxxxxxx).

Erta Ale
Ethopia
13.60°N, 40.67°E; summit elev. 613 m
All times are local (= UTC + 3 hours)
From 7-10 February 2009, an expedition team with Chris Weber visited Erta Ale (figure 10) and observed the long-active lava lake in the S pit crater. Although there have been intervening visits and reports (most recently from February 2008, BGVN 33:06), a comparison of observations from 2002 with 2008-2009 gives a sense of the changes to the craters (table 6).

Figure 10. Aerial photograph of the summit of Erta Ale volcano, viewed from the S in February 2002. The summit contained a 0.7 x 1.6 km elliptical caldera housing two steep-sided craters. Steam rose from the NW pit crater (left), and a lava lake resided in the S pit crater (right). A hornito is just S of the S pit crater. Courtesy of Jurg Alean.

Table 6. Summary of observations made during 2002, 2008,and 2009 of Erta Ale S and NW pits and lava lakes. The numbered terraces (former lake surfaces that chilled sufficiently to leave a conspicuous ledge) are shown on the sketch maps (figure 11). The undated 2008 observations came from the local guide, Meles Matwose. Courtesy of C. Weber.

   Date                Observations (South Crater, South Lava Lake, NW Crater, NW Lava Flows)
   04 Dec 2002         South Crater: Elliptical (terraces #1 and #2) ~ 160 m EW, ~ 130 m NS.
                         Two levels (terraces #1 & 2). About half the area (terrace #1) covered
                         by basalt on terrace ~ 45 m below pit rim.

                       South Lava Lake: About half the area (terrace #2) ~ 100 m EW. Lake
                         surface ~ 90 m below W rim of pit.
                       NW Crater: One level (terrace #3).
   2008                NW Crater: Massive collapse early in year caused new, deeper level
                         (terrace #4).
                       NW Lava Flows: Lava flows covered part of terraces #3 & 4. Latest flow

                         in Nov 2008.
   07-10 Feb 2009      South Crater: Elliptical shape (terraces #1, #2, and the lava lake)
                         ~ 190 m EW, ~ 150 m NS. Three levels (terraces #1, 2, lava lake).
                         Terrace (terrace #1) and 2002 lava lake edge (terrace #2) ~ 35 m

                         below W side of pit rim.
                       South Lava Lake: Lava lake ~ 60 m wide in W half of pit. Lake surface
                         higher than in 2002 and it oscillated ~ 5 m vertically and at times

                         came close to overflowing terraces #1 & 2.
                       NW Crater: Three levels (terraces #3, #4, and #5).
South pit crater. The active S pit expanded due to crater collapse on its W side between 2002 and 2009 (figure 11). The shape of the ellipsoidal crater increased by ~ 30 m EW and ~ 20 m NS.
Figure 11. Sketch maps for part of Erta Ale comparing GPS surveys from December 2002 and February 2009. Data from 2002 courtesy of L. Fitsch (BGVN 28:04). Courtesy of C. Weber.
The former lava-lake stand from 2002 left a remnant surface still visible in 2009 (terrace #2), an area marked as well by fractures and fumaroles. In both 2002 and 2009 terraces #1 and #2 still remained, separated by an elevation difference of ~ 40 m (BGVN 28:04).

During 2009, the W half of the S pit contained a 60 m wide active lava lake (figure 12). Fountaining there took place a few times per day, occasionally throwing spatter above the top of the crater walls. Some recent spatter was seen at the pit's W edge.

Figure 12. The active S crater lava lake in February 2009, with the molten lake surface at a much higher level than during November 2002, sometimes rising close to the terraces #1 and #2. The surface is approximately 35 m below the crater rim. Courtesy of C. Weber.

NW pit crater. In February 2009 the NW crater had preserved ledges at three levels (terraces #3, #4, and #5). This represented a substantive change in comparison to 2002 where only level #3 was observed (figure 11) . According to Weber, a local guide (Meles Matwose) reported that the NW crater had a massive collapse in early 2008, establishing the deeper level #4. Lava flows covering the crater floor occurred at that time, as well as new lava flows at level #4. One of the latest lava flows, observed by Matwose in November 2008, covered a part of a new interior plateau at level #4. When the lava lake stood at the lowest level, #5, very little lava entered the NW crater.

During the February 2009 expedition, some hornitos on level #4 degassed vigorously inside the pit crater, and, on 9 February 2009, lava spattered ~ 15 m high associated with Strombolian emissions ejected at one hornito during 1800 to 2200 hours. Many photos taken inside the Erta Ale craters in January-February 2009 are shown on the Volcano Discovery website.

Films of Erta Ale. Marc Szeglat's Streaming Planet website provides some spectacular film taken December 2002 inside the S pit showing eruptive activity and researchers collecting data. Cameraman and author of the film was Szeglat, and the film narration is in German. Another short film by Szeglat taken in February 2008 is shown on his YouTube channel.

Recent research publication. Spampinato and others (2008) noted that active lava lakes represent the exposed, uppermost part of convecting magma systems and provide windows into the dynamics of magma transport and degassing. They reported on the main features of the lava lake surface in the S pit of Erta Ale based on observations from an infrared thermal camera made on 11 November 2006. Efficient magma circulation was reflected in the sustained transport of the surface, which was composed of pronounced incandescent cracks that separated wide plates of cooler crust. These crossed the lake from the upwelling to the down-welling margin with mean speeds ranging between 0.01 and 0.15 m/s. Hot spots eventually opened in the middle of crust plates and/or along cracks. These produced mild explosive activity lasting commonly between ~ 10 and 200 s. Apparent temperatures of cracks ranged between ~ 700 and 1070°C, and those of crust between ~ 300 and 500°C.

Geologic Summary. Erta Ale is an isolated basaltic shield volcano that is the most active volcano in Ethiopia. The broad, 50-km-wide volcano rises more than 600 m from below sea level in the barren Danakil depression. Erta Ale is the namesake and most prominent feature of the Erta Ale Range. The 613-m-high volcano contains a 0.7 x 1.6 km, elliptical summit crater housing steep-sided pit craters. Another larger 1.8 x 3.1 km wide depression elongated parallel to the trend of the Erta Ale range is located to the SE of the summit and is bounded by curvilinear fault scarps on the SE side. Fresh-looking basaltic lava flows from these fissures have poured into the caldera and locally overflowed its rim. The summit caldera is renowned for one, or sometimes two long-term lava lakes that have been active since at least 1967, or possibly since 1906. Recent fissure eruptions have occurred on the northern flank of Erta Ale.

Reference: Spampinato, L., Oppenheimer, C., Calvari, S., Cannata, A., and Montalto, P., 2008, Lava lake surface characterization by thermal imaging: Erta 'Ale volcano (Ethiopia), Geochemistry Geophysics Geosystems, v. 9, issue Q12008, doi:10.1029/2008GC002164.

Information Contacts: Christoph Weber, Volcano Expeditions International (VEI), Muehlweg 11, 74199, Entergruppenbach, Germany (Email: mail@xxxxxxxx; URL: http://www.v-e-i.de and http://www.volcanic-hazards.de); Hawai'i Institute of Geophysics and Planetology (HIGP) 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/); Streaming Planet (URL: http://www.streaming-planet.de/); Marc Szeglat (Email: szeglat@xxxxxxxx; URL: http://www.youtube.com/marcszeglat and http://www.vulkane.net/); Volcano Discovery (URL: http://www.volcanodiscovery.com/); Jurg Alean, Kantonsschule Zurcher Unterland, Bulach, Switzerland.

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---------- Forwarded message ----------
From: "Venzke, Ed" <VENZKEE@xxxxxx>
To: Volcano_Listserv <volcano@xxxxxxx>

Date: Thu, 24 Sep 2009 14:57:25 -0400
Subject: Bulletin of the Global Volcanism Network, July 2009
****************************************************************
Bulletin of the Global Volcanism Network
Volume 34, Number 7, July 2009
http://www.volcano.si.edu/

****************************************************************

Bulletin of the Global Volcanism Network
Volume 34, Number 7, July 2009

Tungurahua (Ecuador) Eruptions in 2008-2009; two fatalities in sudden flood on 22 August 2008

Galeras (Colombia) Explosions during February-June 2009, ashfall up to 180 km away
Uzon (Russia) Valley of Geysers two years after the major landslide of June 2007
Suwanose-jima (Japan) Explosive eruptions continue through 6 July 2009

Makian (Indonesia) Seismicity increased during May 2009 after tectonic earthquakes
Talang (Indonesia) Sudden occurrence of over 900 earthquakes on 16-17 August 2009
Sangeang Api (Indonesia) Increased seismicity, including explosion earthquakes, during May-June 2009

Rumble III (Kermadec islands) Submarine summit craters underwent collapse and eruption
Erta Ale (Ethiopia) Changes at NW and S pit craters between 2002 and 2009

Editors: Rick Wunderman, Edward Venzke, and Sally Kuhn Sennert

Volunteer Staff: Ludmila Eichelberger, Russell Ross, Paul Berger, Hugh Replogle, Robert Andrews, Catie Carter,
Margo Morell, Jacquelyn Gluck, and Stephen Bentley

Tungurahua
Ecuador
1.467°S, 78.442°W; summit elev. 5,023 m

All times are local (= UTC - 5 hours)

Our previous report on Ecuador's Tungurahua (BGVN 33:06) summarized the ongoing activity through mid-February 2008. This report covers February 2008-July 2009. The Instituto Geofisico-Escuela Politecnica Nacional (IG) has maintained a continuous watch on Tungurahua in order to provide immediate alert of significantly heightened activity to prevent as much damage to property and population as possible. Several pyroclastic flows occurred.