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Global Volcanism Program (http://www.volcano.si.edu/)
Bulletin of the Global Volcanism Network
Volume 32, Number 5, May 2007
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Chikurachki (Russia) Ash plumes during March and April 2007; ashfall and an SO2 cloud
Mayon (Philippines) Eruption ends on 1 October 2006; typhoon causes deadly lahars
Karangetang (Indonesia) Frequent activity since 2004, including lava emission and pyroclastic flows
Ritter Island (Papua New Guinea) Eruption on 19 May causes landslides and sea surges
Garbuna Group (Papua New Guinea) Boiling water in two summit craters, low seismicity
Rabaul (Papua New Guinea) Ash plumes, crater glow, and roaring through April and May
Lopevi (Vanuatu) New eruptive episode with ash plumes and thermal anomalies during April-May
Ambrym (Vanuatu) Lava lakes active again starting in January 2007; ash plumes
Unnamed (Tonga) Bathymetric survey locates vent area and maps 2001 pumice deposits
Kilauea (Hawaii, USA) Lava flows entering the ocean between December 2006 and March 2007
Editors: Edward Venzke, Rick Wunderman, and Sally Kuhn Sennert
Volunteer Staff: Robert Andrews, Hugh Replogle, Michael Young, Paul Berger, Jerome Hudis, Veronica Bemis, Jacquelyn Gluck,
Jerome Bucceri, Kelly Kryc, Margo Morell, Stephen Bentley, Antonia Bookbinder, and Jeremy Bookbinder
Chikurachki
Kuril Islands, Russia
50.325°N, 155.458°E; summit elev. 1,816 m
Several ash plumes, weak fumarolic activity, and ashfall occurred during March and April 2005 (BGVN 31:03). No further activity was reported until 4 March 2007, when weak ash explosions from Chikurachki were reported by residents of Podgorny, about 20 km ESE on Paramushir Island (figure 1). Chikurachki is not monitored with seismic instruments, so the Kamchatkan Volcanic Eruption Response Team (KVERT) relies on satellite data and occasional visual observations.
Figure 1. Map of the northern Kurile Islands and southern portion of Kamchatka Peninsula. From National Oceanic and Atmospheric Administration Tactical Pilotage Chart ONC-E10C, as provided by McGimsey and others (2005).
On 5 March 2007, observers reported that a continuous ash column reached an altitude of 3.4 km. Ash plumes were also observed by satellite imagery during 11-12 March, 4-5 April, 9 April, 14-16 April, and 18 April. On 4 April, ashfall was noted at Severo-Kurilsk, 62 km NE. Hunters near the volcano observed bursts of volcanic bombs on 15 April. Satellite data analysis provided by the Volcanic Emissions Group at the University of Maryland Baltimore County revealed a sulfur dioxide cloud on 16 March 2007 extending 580 km NW at an unknown altitude.
According to KVERT, no eruptive activity has been noted since about 20 April. The concern color code was reduced from Orange to Yellow during the week of 20 April, and then to Green (lowest risk) during the week of 11 May.
Reference: McGimsey, R.G., Neal, C., and Girina, O., 2005, 2003 volcanic activity in Alaska and Kamchatka summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey report 2005-1310, http://pubs.usgs.gov/of/2005/1310.
Geologic Summary. Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is actually a relatively small cone constructed on a high Pleistocene volcanic edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the young cone give it a distinctive red color. Frequent basaltic plinian eruptions have occurred from Chikurachki during the Holocene. Lava flows from 1816-m-high Chikurachki reached the sea and form capes on the NW coast; several young lava flows also emerge from beneath the scoria blanket on the eastern flank. The Tatarinov group of six volcanic centers is located immediately to the south of Chikurachki. In contrast to the frequently active Chikurachki, the Tatarinov volcanoes are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of only one eruption in historical time from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.
Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky 683006, Russia (Email: girina@xxxxxxxxxx); Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/; Email: tlmurray@xxxxxxxx); Tokyo Volcanic Ash Advisory Center, Tokyo, Japan (URL: http://www.ssd.noaa.gov/ VAAC/OTH/JP/messages.html); Volcanic Emissions Group, based in the Joint Center for Earth Systems Technology at the University of Maryland Baltimore County and NASA Goddard Space Flight Center, 1000 Hilltop Circle, Baltimore, MD 21250, USA (URL: http://so2.umbc.edu/omi/).
Mayon
Luzon, Philippines
13.257°N, 123.685°E; summit elev. 2,462 m
The eruption from Mayon that began on 13 July 2006 (BGVN 31:07) ended in early October. By mid-September 2006, the volcano's eruptive vigor had decreased (BGVN 31:08). According to reports by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) through 3 October, low-frequency harmonic tremor was not recorded after 24 September, crater glow was last seen on 27 September, and tremor episodes were not detected after 30 September. Sulfur-dioxide flux was also low on 26 September, 1,200 metric tons per day (t/d), but could not be measured the following week due to poor weather. On 3 October PHIVOLCS noted that there had been a continuous decline in overall activity since 11 September. Lava extrusion apparently ceased on 1 October 2006, as reported by the Ligñon Hill Observatory. As a result, the hazard status was lowered to Alert Level 2, indicating that the possibility of a hazardous eruption was remote.
Fumarolic activity on 30 September and 1 October produced white steam plumes that drifted ENE. On 11 and 12 October steaming was moderate and one volcanic earthquake was recorded. During the first week of October, six low-frequency volcanic earthquakes and one low-frequency short duration harmonic tremor were recorded. Crater glow was seen again on 4 October. The SO2 flux measured on 6 October remained low at 1,600 t/d.
On 25 October, PHIVOLCS announced the lowering of the hazard status to Alert Level 1. The 7-km Extended Danger Zone on the SE flank remained in effect. At that time the number of daily volcanic earthquakes was below background levels (1-5 per day), tremor episodes were rare, there was no ground deformation, SO2 emission was within the typical 1,600-2,650 t/d range, and the observed glow remained at a consistent intensity.
Lahars caused by tropical storm. Typhoon Durian, also called Reming, struck the Philippines on 30 November and mobilized material from the flanks of Mayon that resulted in significant lahars, burying thousands of homes under 1.5 m of volcanic debris, mud, and flood waters. Official government information releases as of 13 December noted that the torrential rains and mudslides, particularly in the area of Mayon, killed 720 people, injured 2,360 others, and left 762 people missing. In addition, 328,218 houses were partially damaged and 214,400 houses were destroyed. A map produced by the United Nations Institute for Training and Research (UNITAR) Operational Satellite Applications Programme (UNOSAT) indicated that about 51 km2 on the flanks of Mayon was damaged by the flooding and mudslides.
Geologic Summary. Beautifully symmetrical Mayon volcano, which rises to 2462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from strombolian to basaltic plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1200 people and devastated several towns.
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Associated Press (URL: http://www.ap.org/); Agence France-Presse (URL: http://www.afp.com/); United Nations Institute for Training and Research (UNITAR) Operational Satellite Applications Programme (UNOSAT), Palais des Nations, CH - 1211 Geneva 10, Switzerland (URL: http://www.unosat.org/); United Nations Office for the Coordination of Humanitarian Affairs (OCHA) (URL: http://www.reliefweb.int/).
Karangetang [Api Siau]
Sangihe Islands, Indonesia
2.78°N, 125.40°E; summit elev. 1,784 m
Since the end of an eruptive period in October 2003 (BGVN 28:11 and 29:03), recent activity has been centered at Crater I (S crater) and Crater II (N crater), of the five summit craters (figure 2). Activity since late 2003 has included ash plumes, lava flows, lava avalanches, and pyroclastic flows. There have been five periods when thermal anomalies were detected in MODIS satellite data from January 2004 through March 2007 (figure 3). However, the gaps between such episodes may in part be caused by clouds obscuring the summit, so they cannot be correlated to eruptive episodes. Intermittent reports made available by the Center of Volcanology and Geological Hazard Mitigation (CVGHM) since June 2004 provide additional observations and seismic data, and sometimes note eruptive activity during periods of gaps in MODIS thermal anomalies. These reports are also not provided on a regular basis, and the lack of reports for a time period does not necessarily indicate a lack of activity.
Figure 2. Topographic map and N-S profiles of Karangetang showing the five summit craters. Craters I (KI) and II (KII) are currently active. The topographic base map is from 1962; roughly N-S profiles are from 1992 (top) and July 2001 (bottom), showing the changes caused by dome growth. Courtesy of CVGHM.
Figure 3. Plot showing days with MODIS thermal anomalies during January 2004-February 2007. Scale indicates the five arbitrary thermal anomaly periods, and does not reflect anomaly magnitudes. Eruptive activity was also reported on some occasions during gaps in thermal anomalies. Compiled from MODIS/HIGP data.
Activity during April-November 2004. After a single thermal anomaly on 5 April 2004, another nine anomalies were seen in MODIS data during 5 May to 29 June. Observations provided by the CVGHM indicated continuing activity during this period. Reports from 31 May onward through 29 August noted that activity was centered at Crater I, but visual observations were often prevented by fog. On clear days white plumes rose 100-400 m above the crater rim. Incandescent glow seen at night reached 10-25 m above the summit. At Crater II, diffuse white plumes reached 25-50 m above the rim. During the three weeks of 9-29 August the reports also included observations of incandescent material and sounds of lava avalanches. Ten avalanche signals were recorded the week of 16-22 August. Shallow B-type volcanic earthquakes also increased significantly (table 1).
Table 1. Seismicity at Karangetang during 24 May-29 August 2004. Courtesy of CVGHM.
Date Volcanic Volcanic Multi-phase
A-type B-type
24 May-30 May 2004 4 12 5
31 May-06 Jun 2004 10 35 7
07 Jun-13 Jun 2004 22 22 4
14 Jun-20 Jun 2004 11 22 4
21 Jun-27 Jun 2004 45 49 13
28 Jun-04 Jul 2004 6 7 3
05 Jul-11 Jul 2004 16 30 1
12 Jul-18 Jul 2004 11 29 3
19 Jul-25 Jul 2004 11 18 16
26 Jul-01 Aug 2004 14 12 2
02 Aug-08 Aug 2004 12 75 11
09 Aug-15 Aug 2004 86 259 60
16 Aug-22 Aug 2004 10 153 74
23 Aug-29 Aug 2004 9 56 68
Between 16 October and 26 November 2004, thermal anomalies were again frequent. On 25 October the hazard status was raised due to increasing volcanism over the previous two days. A larger area of incandescence was noted at the summit, and a lava flow descended 800 m. No other reports of observations were available between September and November 2004.
Activity during January-March 2005. Thermal anomalies reappeared in MODIS satellite data on 6 February 2005, and continued to be detected on an almost daily basis through 24 March. CVGHM reports noted lava avalanches starting on 3 January 2005, accompanied by booming noises. During 24-30 January white gas plumes were emitted 50 m above both craters, and a 10- m-high glare was observed at night inside the plume from Crater II. Lava avalanches since 26 January originated from the lava-flow front, moving 750-1,200 m towards the Beha Barat River, 750-2,200 m towards the Batu Awang River, and 1,750 m towards the Kahetang River.
Lava avalanches in the first half of February had run-out distances of 1,250 m down the Beha River drainage, 700 m down the Batu Awang, 1,750 m down the Kahetang, and 1,200 m down the Nanitu. Incandescent material during this period was ejected ~25 m into the air and fell back into the crater. On 16 February, a lava flow advanced 600 m from the crater towards the Nanitu River. A pyroclastic flow later that evening from the lava front traveled 3.4 km and reached the sea, ~4 km from the summit. Lava avalanches from flow-fronts continued into late February toward the Beha, Kahetang, Batu Awang, and Nanitu drainages to distances of 500-1,200 m. These avalanche events produced continuous booming sounds and also "glowing bursts" to heights of 10-25 m. Gas emitted from Crater I rose 50-200 m, and a glare could be seen inside the gas column to heights of 25-75 m. Crater II also produced gas emissions 50-150 m high.
No additional reports are available until a mid-April 2005 report indicated that the volcano was still at a Level III hazard status. During clear weather over 2-9 May, a 400-m-high white gas plume rose from Crater I; there was a 25-m-high glare inside it. Meanwhile, Crater II emitted a white gas plume as high as 100 m. Due to the continuing possibility of pyroclastic avalanches and lahars during the rainy season, residents were not allowed within 2 km of the edge of the lava flow. On 30 May, based on a pilot observation, the Darwin VAAC reported ash at a height below 3 km drifting E; however ash was not visible on satellite imagery.
Activity during August-December 2005. The Darwin VAAC again issued an ash advisory on 2 August regarding a plume to an altitude of 4.6 km. This ash cloud, which continued through 4 August without significant interruptions, was occasionally discernable on both MTSAT and NOAA -12 satellites. Between 26 September and 16 October CVGHM reports again noted white gas rising 200-250 m from Crater I with a 25-m-high glare at the bottom of the gas column, and a 150-m gas emissions from Batukole crater. Tremor continued during 30 November-13 December 2005, but no other activity was described. Karangetang remained at Alert Level 3.
Activity during July-September 2006. Single MODIS thermal anomalies were seen on 11 February 2006, 18 May, and 8 June. Hot spots were then seen almost daily during 13 July-30 September. The Darwin VAAC noted a small eruption on 3 July 2006 with an ash plume to an altitude of 3.7 km observed on satellite imagery. On 12 July, lava flows were moving E toward the Kahetang and Batu Awang rivers, reaching a maximum distance of 2 km. White emissions rose 600 m above the crater. Having previously been lowered, the hazard status was raised from 2 to 3 on 13 July, and then to Alert Level 4 on 22 July due to increased eruptive activity. Lava flows 1.8 km from the vent were observed on 20 July moving E toward the Kahetang and Batu Awang rivers, were 2 km long towards the Keting River, and 400 m S towards the Bahembang River.
On 21 July, a pyroclastic flow from the upper S flank traveled 2.5 km toward the Batu Awang River and was followed by lava flows that traveled toward the Keting and E towards the Kahetang rivers, reaching a maximum runout distance of 2 km. On 22 July, Electronic Distance Measurement equipment indicated deformation measurements indicative of a bulge of about 3-5 mm. Diffuse white smoke was seen at a height of ~350 m above the summit. Lava flows traveled a maximum distance of ~2.3 km towards the Keting and S towards the Bahembang rivers during 22-23 and 25 July.
On 1 and 2 August 2006, lava flows traveled up to 500 m E toward the Batu Awang river and 300-750 m S towards the Keting River and white plumes reached heights of 50-300 m above the summit. Incandescent rockfalls originating from the summit and termini of the lava flows traveled 500-1,500 m E toward the Kahetang and Batu Awang rivers, S towards the Keting River, and occasionally 500 m S towards the Batang River. During 3-4 August, lava flows traveled up to 500 m E toward the Batu Awang river and 100-750 m S towards the Keting. During 7-13 August, lava flows again advanced E toward the Batu Awang river. Incandescent rockfalls originating from ends of the lava flows were also observed.
Activity from mid-August through September 2006 was relatively uneventful. The Darwin VAAC reported and ash cloud on 11 September. On 24 November the Darwin VAAC, reported an eruption that produced a small ash plume observed on satellite imagery that reached an altitude of 3 km.
Activity during November 2006-April 2007. After about six weeks without being detected, thermal anomalies were again frequently seen from 17 November through 11 January 2007. On 14 February the Alert Level was reduced from 3 to 2. Tremor events were recorded at a rate of 52/day over the previous two months, but had not increased since the 21 July 2006 pyroclastic flows, and earthquakes were shallow. Crater I continued to emit a thin trace of white gas 100-300 m above the crater rim. Emissions from Crater II rose to 50-250 m, with occasional incandescence up to 50 m.
Karangetang was relatively quiet until 28 March when a gas cloud was observed up to 100 m above the crater rim. According to a news article in the Jakarta Post, increased activity starting on 26 March led to the emission of "hot clouds" over the next two days. Based on satellite imagery and analysis from the US Geological Survey, the CVGHM reported that sometime between mid-March and 6 April the lava dome in the northern crater had collapsed and was replaced by a new dome ~40 m in diameter. A MODIS thermal anomaly was detected on 3 April. During 23-29 April only dense white plumes were observed from Crater II.
Geologic Summary. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The 1784-m-high stratovolcano contains five summit craters along a N-S line. Karangetang is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.
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) Hot Spots System, University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Jakarta Post, Indonesia (URL: http://www.thejakartapost.com/).
Ritter Island
Northeast of New Guinea, Papua New Guinea
5.52°S, 148.121°E; summit elev. 140 m
On 17 October 2006 occasional small earthquakes on Ritter Island were followed by emissions of white vapor and diffuse ash clouds, occasional rock slides from the inner crater wall, and ashfall on nearby Umboi (Siassi) Island (BGVN 32:03). No further activity was reported until 19 May 2007, when sea surges destroyed a boat and four houses on Umboi following an eruption, according to media quotes from Morobe Province disaster and emergency director Roy Kamen. Kamen also noted that 1,500-2,000 people from two villages had moved to higher ground for fear of tsunamis. As of 21 May residents could still hear rumbling noises, see "smoke" rising from Ritter Island, and feel tremors. The Rabaul Volcanological Observatory (RVO) and the Geophysical Observatory in Port Moresby did not record seismic activity from the eruption on their equipment.
Reports received by RVO from Jonathan Kuduon at Kilenge (western New Britain) on 30 May indicated evidence of high waves (4-10 m high) around Ritter Island, with a maximum of 10 m on the S part of the island. Scorched vegetation was seen in the same area, and dead marine animals, mainly reef fish, were seen around the coastline. There was no evidence of fresh volcanic material, but a new landslide scar was visible on the S tip of island, an area that extended from the uppermost part of the island (~100 m elevation) down to sea level. Several other small landslide scars were seen on the W wall. Rockfalls continued to produce clouds that could be seen from a distance. Seismic activity was low during one day of recording on 27-28 May; only four high-frequency earthquakes were recorded.
RVO noted that the event on 19 May was similar to the 1972 and 1974 events, in that they lasted only a few hours and were preceded by explosion noises followed by disturbance of the sea. Both the 1972 and 1974 activities occurred offshore, and landslides were triggered during the 1974 activity. The 19 May event may have been due submarine explosions or earthquakes associated with volcanic activity that triggered the landslide(s).
Geologic Summary. Prior to 1888, Ritter Island was a steep-sided, nearly circular island about 780 m high. The current small, 140-m-high island is a topographically insignificant, 1900-m-long arcuate feature between Umboi and Sakar Islands. Several historical explosive eruptions had been recorded prior to 1888, when large-scale slope failure destroyed the summit of the conical basaltic-andesitic volcano, leaving the arcuate 140-m-high island remnant with a steep west-facing scarp that descends below sea level. Devastating tsunamis were produced by the collapse and swept the coast of Papua New Guinea and offshore islands. Two minor post-collapse explosive eruptions, during 1972 and 1974, occurred offshore within the largely submarine 3.5 x 4.5 km breached depression formed by the collapse.
Information Contacts: Herman Patia, Rabaul Volcanological Observatory (RVO), Department of Mining, Private Mail Bag, Port Moresby Post Office, National Capitol District, Papua New Guinea (Email: hguria@xxxxxxxxxxxxx); Australian Associated Press, AAP News Centre, 3 Rider Boulevard, Rhodes Waterside, Rhodes, NSW 2138, Australia (URL: http://aap.com.au/).
Garbuna Group
New Britain, Papua New Guinea
5.45°S, 150.03°E; summit elev. 564 m
According to the Rabaul Volcanological Observatory (RVO), Garbuna remained quiet from February 2006 through 10 June 2007. Two vents produced the first historically witnessed eruption from this volcano in October 2005 (BGVN 30:11). At least one summit vent continued to release small-to-moderate volumes of white vapor that could be seen from the observation post 15 km SE. There have been no noises heard nor glow observed at night.
An aerial inspection on 2 February 2006 revealed that both summit vents had increased in size and contained vigorously boiling water. The town of Kimbe (-16.6 km SE) experienced continuous rainfall during the days prior to this inspection. A weak smell of sulfur was detected 5 km E of Garbuna on 2 February. Seismic activity was at a low level, between 0 and 9 earthquakes per day, dominated by high-frequency events. Some low-frequency events were also recorded. A faulty seismometer at the summit was replaced and a new global positioning system (GPS) station for monitoring ground deformation was installed on 2 February 2006.
During December 2006 through 10 June 2007, seismicity continued at a low level, dominated by high-frequency volcanic earthquakes (87 in number) recorded daily; none were located due to insufficient seismic stations. Daily totals in December 2006 ranged between 1 and 16 earthquakes, the highest number of events (16) being recorded on 22 December 2006. No low-frequency earthquakes were recorded during December 2006. During January through 10 June 2007 there were 2-3 daily high-frequency events on average, with up to 5 on some days. The summit seismograph picked up continual tremor from the boiling lake in the main vent. Technical problems with the summit seismometer were experienced at times in March, May, and June. Based on GPS measurements, ground deformation showed no significant changes during this period.
Geologic Summary. The basaltic-to-dacitic Garbuna volcano group consists of three volcanic peaks, Krummel, Garbuna, and Welcker. They are located along a 7-km N-S line above a shield-like foundation at the southern end of the Willaumez Peninsula. The central and lower peaks of the centrally located 564-m-high Garbuna volcano contain a large vegetation-free area that is probably the most extensive thermal field in Papua New Guinea. A prominent lava dome and blocky lava flow in the center of thermal area have resisted destruction by thermal activity, and may be of Holocene age. The 854-m-high Krummel volcano at the south end of the group contains a summit crater, breached to the NW. The highest peak of the Garbuna group is 1005-m-high Welcker volcano, which has fed blocky lava flows that extend to the eastern coast of the peninsula. The last major eruption from both it and Garbuna volcanoes took place about 1800 years ago. The first historical eruption of the complex took place at Garbuna in October 2005.
Information Contacts: Herman Patia, Steve Saunders, and Felix Taranu, Rabaul Volcano Observatory (RVO), PO Box 3386, Rabaul, E.N.B.P, Papua New Guinea (Email: hguria@xxxxxxxxxxxxx).
Rabaul
New Britain, Papua New Guinea
4.271°S. 152.203°E; summit elev. 688 m
Eruptive activity continued from the Tavurvur cone during April and May 2007, with ash plumes drifting downwind in various directions. A large Vulcanian eruption from the Tavurvur cone occurred at Rabaul on 7 October 2006 (BGVN 31:09). After activity varied in intensity through the end of December 2006 (BGVN 31:10), generally mild eruptive activity was reported by the Rabaul Volcano Observatory (RVO) through March 2007 (BGVN 32:02).
During 3-17 April, the RVO and Darwin Volcanic Ash Advisory Centre (VAAC) reported that Tavurvur emitted steam and steam-and-ash plumes that rose to a maximum of 3 km altitude. Occasional weak roaring noises accompanied the emissions. On 3 April, explosions shook buildings in Rabaul town. Incandescent material was ejected from the crater during the night of 9-10 April and moderate to strong sub-continuous roaring could be heard in Rabaul town. Small amounts of incandescent material were ejected from the crater during 13-15 April. White to gray emissions during 16-25 April generated plumes that rose a few hundred meters. A diffuse plume seen on satellite imagery rose to an altitude of 1.5 km on 18 April. Minor ashfall was reported in Rabaul town from 22 to 25 April, when moderately-sized explosions led to darker gray plumes. On 29-30 April, ash emissions generated plumes that rose to an altitude of 1.2 km. Seismicity continued to remain at low levels. There were no high-frequency events or explosions recorded, but there were some small low-frequency events associated with roaring noises.
During 1-2 May, ash plumes drifted NNW and ashfall was reported at Rabaul town and surrounding areas. After that, emissions from Tavurvur were mostly steam that only rose 500 m. After heavy rains in the first week of May, the night-time red glow disappeared, but roaring noises intensified. Roaring noises were heard throughout May, but were more intense after heavy rainfall. Weak to moderate glow was visible during the last three weeks of the month. Seismicity remained at low levels. Small low-frequency earthquakes associated with the roaring noise dominated the seismic activity. There was a gradual increase in the daily number of low-frequency events from less than 10 during the second week to a peak of 50 during the third week before declining back to less than 10 at the end of the month. Ground deformation measurements indicated no apparent changes during the month.
Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the E, where its floor is flooded by Blanche Bay and was formed about 1,400 years ago. An earlier caldera-forming eruption about 7,100 years ago is now considered to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the northern and NE caldera rims of Rabaul. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.
Information Contacts: Steve Saunders and Herman Patia, Rabaul Volcanological Observatory (RVO), Department of Mining, Private Mail Bag, Port Moresby Post Office, National Capitol District, Papua New Guinea (Email: hguria@xxxxxxxxxxxxx, URL: http://www.pngndc.gov.pg/Volcano%20Bulletins.htm); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Darwin, Australia (Email: A.Tupper@xxxxxxxxxx, darwin.vaac@xxxxxxxxxx).
Lopevi
Vanuatu, SW Pacific
16.507°S, 168.346°E; summit elev. 1,413 m
All times are local (= UTC + 11 hours)
No eruptive activity was evident from Lopevi following the June-July 2006 episode (BGVN 32:02) until 21 April 2007. Between 21 April and 14 May 2007 thermal anomalies detected by satellites again became an almost daily event. This was the fourth eruptive episode since October 2005 (table 2). No anomalies were observed after 14 May through 26 June 2007.
Table 2. Summary of MODIS thermal anomaly measurements at Lopevi from 27 October 2005 to 26 June 2007. "Nearly daily anomalies" indicate gaps in measurements of no more than 3-4 days, unless otherwise noted; these may be due to obscuring cloud cover. Courtesy of Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alert System.
Period Observations
27 Oct 2005-25 Jan 2006 Nearly daily anomalies except for two 8-day and two 7-day periods;
1-4 pixels per satellite measurement (8 pixels on 21 December).
26 Jan 2006-24 Apr 2006 No thermal anomalies measured for about 90 days.
25 Apr 2006-28 May 2006 Nearly daily anomalies except for one 7-day period; 1-5 pixels per
satellite measurement (12 pixels on 13 May, 23 pixels on 2 May).
29 May 2006-25 Jun 2006 No thermal anomalies measured for about 28 days.
26 Jun 2006-31 Jul 2006 Nearly daily anomalies except for one 7-day period; 1-7 pixels per
satellite measurement (11 pixels on 28 June, 10 pixels on 7
July).
01 Aug 2006-20 Apr 2007 No thermal anomalies measured for about 260 days.
21 Apr 2007-14 May 2007 Nearly daily anomalies; 1-7 pixels per satellite measurement (9
pixels on 22 April, 11 pixels on 23 April, 10 pixels on 24
April, 11 Pixels on 26 April, 10 pixels on 28 April, and 9
pixels on 31 April).
15 May 2007-26 Jun 2007 No thermal anomalies measured for about 40 days.
Based on pilot reports and satellite imagery, the Wellington VAAC reported that ash plumes rose to altitudes of 2.4-4.6 km during 21-24 April 2007. The plume on the 22nd was described as being a very dense dark gray ash plume with a steady growth rate. On 25 April a pilot reported that an ash plume covered the vent. A light brown eruption cloud over the island that drifted E from Lopevi on 3-4 May was detected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite (figure 4). The gray-brown plume became more diffuse downwind, with a pale gray plume spreading SE and N. Aviation notices from the Wellington VAAC noted that wind models indicated light easterly winds below 3 km, tending northerly above 1.8 km altitude. A pilot reported that the plume rose to 2.1 km altitude. The U.S. Air Force Weather Agency reported an extensive area of vog (volcanic smog) resulting from the eruption.
Figure 4. Satellite image of an ash plume from Lopevi, 3 May 2007. The plume appears as a small, mostly opaque gray-beige puff. The area of vog, which appears as a more transparent, dingy-gray haze, dwarfs the diminutive plume. Courtesy of NASA Earth Observatory.
Geologic Summary. The small 7-km-wide conical island of Lopevi, known locally as Vanei Vollohulu, is one of Vanuatu's most active volcanoes. A small summit crater containing a cinder cone is breached to the NW and tops an older cone that is rimmed by the remnant of a larger crater. The basaltic-to-andesitic volcano has been active during historical time at both summit and flank vents, primarily along a NW-SE-trending fissure that cuts across the island, producing moderate explosive eruptions and lava flows that reached the coast. Historical eruptions at the 1413-m-high volcano date back to the mid-19th century. The island was evacuated following major eruptions in 1939 and 1960. The latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow that swept to the sea and a lava flow that formed a new peninsula on the western coast.
Information Contacts: NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); 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/); Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html).
Ambrym
Vanuatu, SW Pacific
16.25°S, 168.12°E; summit elev. 1,334 m
All times are local (= UTC + 11 hours)
Thermal anomalies detected by the MODIS satellite instrument showed that the lava lakes present in Benbow and Marum craters, which have been almost continuously active since early 2001 (BGVN 29:06), continued until 19 June 2005. Ash had apparently stopped falling on 1 June, though a haze of SO2 was noted on 17 June (BGVN 30:05). Thermal anomalies were not regularly seen again until 11 January 2007. The only exceptions occurred from Benbow on 14 April 2006 (one pixel) and from Marum on 8 and 15 November 2006 (one and two pixels, respectively). Thermal anomalies were seen on 11 and 15 January, again during 3-19 February, and then almost daily after 9 March through at least the end of May. The current lava-lake activity, as determined by MODIS data, seems to be confined to the Marum crater area.
The Wellington Volcanic Ash Advisory Center (VAAC) reported that on 3 April 2007 pilots observed lava and ash emissions from Ambrym; ash plumes rose to altitudes below 2.4 km. On 1 May at 1330 satellite imagery showed an ash cloud with NE winds at the surface turning to NW above an altitude of 3 km. On next day at 0715 a pilot observed a vertical plume extending 37 km NW at an altitude of 4 km. On 3 May at 0900 a pilot identified an ash cloud below an atmospheric temperature inversion at an altitude of -1.8 km drifting SE. Ash was visible on satellite imagery at 1310 on 3 May.
Steven Clegg and Kelby Hicks reported that the volcano continued to exhibit strong degassing from both Marum (figure 5) and Benbow vents from 26 May to 12 June 2007. Within the Mbwelesu crater a lava lake appeared in May 2007, while the group was there, and continued to be visible through 12 June (figure 6). Fumarolic activity was visible throughout the interior of Mbwelesu Crater with intermittent ash eruptions and light tephra emissions. Extra-crater tephra fall included Pele's Hair, reticulite, spatter, and scoria-sized ejecta. Both Niri Mbwelesu and Mbogon Niri Mbwelesu (formerly Niri Mbwelesu Taten) craters exhibited notable fumarolic degassing, but no other observable activity. No lava lake could be seen from the rim of Benbow crater; however, a strong glow above Benbow was visible during night observations.
Figure 5. View of the Marum cone at Ambrym looking SW, 7 June 2007. Incandescence from the active lava lakes can be seen reflected in the clouds (left). Courtesy of Steven Clegg.
Figure 6. Lava lake inside Mbwelesu crater within Marum cone at Ambrym, 7 June 2007. Courtesy of Steven Clegg.
Geologic Summary. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.
Information Contacts: Steven G. Clegg and Kelby E. Hicks, Volcan, Inc., P.O. Box 1287, Austin, TX 78767, USA (URL: http://www.volcan.org/); Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html); 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/).
Unnamed
Tonga Islands, SW Pacific
18.314°S, 174.384°W; summit elev. -40 m
An echo sounding depth survey of a recently active unnamed volcanic seamount (volcano number 0403-091) ~50 km NW of Vava'u was undertaken on 23 February 2007. The seamount is located within a roughly N-S segment of the submerged Tofua volcanic arc on a relatively broad plateau of less than 1,000 m depth, upon which five other seamounts rising to depths of 100 m are indicated on current bathymetric maps. One seamount indicated to shoal to depths of ~270 m, based on a reported spot depth recording in 1965, may correspond to this volcano.
No depth soundings were recorded at the previously described location of this volcano, with reported depths greater than 91 m. About 1.85 km (~1 nautical mile) to the NW, an area of shallow water (61-40 m) was mapped (figure 7). A relatively flat-topped seamount occurs with a maximum length of ~1.2 km (NW-SE) and 0.83 km width (NE-SW); much of the summit region is at or above 53 m below sea level. Two domal peaks cap the seamount and flank a depression on the E side. In profile, the seamount is steep-flanked, descending to water depths below 61 m over very short horizontal distances.
Figure 7. Bathymetric map and cross section of the unnamed Tongan seamount (volcano number 0403-091). NS: no depth sounding (ie. beyond depth-sounder range). Courtesy of Scott Bryan.
Two peaked areas on the seamount summit are inferred to represent pumice and other juvenile dacitic deposits from the 2001 eruption (BGVN 26:11 and 27:01). The broader domal area on the NW side would be consistent with maximum pumice deposition in response to NW-directed wind and ocean currents at the time of eruption and the dispersal of pumice rafts. Based on the summit profiles, at least 12 m of juvenile material erupted during the 2001 eruption may have accumulated on the summit. The prominent depression on the E side of the summit may therefore correspond to the vent area of the 2001 eruption, where crater floor depths are more than 61 m below sea level. The bathymetric survey indicates that the 2001 submarine dacitic explosive eruption occurred in shallow water depths (< 100 m).
General References: Bryan, S.E., 2007, Preliminary Report: Field investigation of Home Reef volcano and Unnamed Seamount 0403-091: Unpublished Report for Ministry of Lands, Survey, Natural Resources and Environment, Tonga, 9 p.
Bryan, S.E., Cook, A., Evans, J., Colls, P., Lawrence, M., Wells, M., Jell, J.S., Greig, A., and Leslie, R., 2004, Pumice rafting and faunal dispersion during 2001-2002 in the southwest Pacific: record of a dacitic submarine explosive eruption from Tonga: Earth and Planetary Science Letters, v. 227, p. 135-154.
Taylor, P.W., 2002, Volcanic hazards assessment following the September-October 2001 eruption of a previously unrecognised submarine volcano W of Vava'u, Kingdom of Tonga: Australian Volcanological Investigations, AVI Occasional Report No. 02/01, p. 1-7.
Geologic Summary. A submarine volcano along the Tofua volcanic arc was first observed in September 2001. The newly discovered volcano lies NW of the island of Vava'u about two-thirds of the way between Late and Fonualei volcanoes. The site of the eruption is along a NNE-SSW-trending submarine plateau south of Fonualei with an approximate bathymetric depth of 300 m. T-phase waves were recorded on September 27-28, and on the 27th local fishermen observed an ash-rich eruption column that rose above the sea surface. No eruptive activity was reported after the 28th, but water discoloration was documented during the following month. In early November rafts and strandings of dacitic pumice were reported along the coast of Kadavu and Viti Levu in the Fiji Islands. The depth of the submarine vent following the eruption is not known.
Information Contacts: Scott Bryan, School of Earth Sciences & Geography, Kingston Univ., Kingston Upon Thames, Surrey KT1 2EL, United Kingdom (Email: s.bryan@xxxxxxxxxxxxxx); Peter Colls, School of Physical Sciences, Univ. of Queensland, St Lucia, Queensland 4072, Australia (Email: p.colls@xxxxxxxxxxxxxxxxx).
Kilauea
Hawaiian Islands, USA
19.421°N, 155.287°W; summit elev. 1,222 m
Lava from Kilauea has continued to flow from a lava delta into the ocean at the East Lae`apuki and East Ka`ili`ili entries from early December 2006 through the end of March 2007. Incandescence remained visible on the Pulama pali fault scarp and coastal flats in the vicinity of the Campout flow while incandescence at the East Pond vent, January vent, South Wall complex, and Drainhole and Beehive vents in Pu`u `O`o's crater remained intermittent. On 5 December 2006, a large breakout on Pulama pali resulted in downed and burned trees. On 27 and 28 December, lava streams were seen descending to the ocean to re-establish the Kamokuna entry (figure 8).
Figure 8. View of the Kamokuna ocean entry of the Campout flow from Kilauea, taken from the sea cliff, 27-28 December 2006. Photo courtesy of Ralf Krug.
During January and February, lava continued to flow from a lava delta into the ocean at East Lae'apuki, Kamokuna (figure 9), and East Ka'ili'ili entries with incandescence intermittently visible on the pali from the East Pond and January vents, South Wall complex, and Drainhole vent in Pu`u `O`o crater. On 12 January, the summit tilt network recorded the start of the tenth deflation-inflation (DI) event; after 7 microradians of deflation the largest of the earlier events was approximately 2 microradians. Inflation began on 13 January with increased and decreased tremor near Pu`u `O`o in response to the DI event. On 24 January, breakout lava from the Campout flow advanced approximately 1.6 km per hour. A USGS field crew reported several smaller breakouts of lava from the flow at the base of the pali that flowed E and burned trees near the long-abandoned Royal Gardens subdivision.
Figure 9. Visible steam plumes from the Kamokuna ocean entry at Kilauea, 22 February 2007. Courtesy of HVO.
Breakout surface lava from the Campout flow produced seven lava falls over the seacliff behind the East Lae'apuki bench on 15 February and continued throughout the week. On 22 February, HVO field crews reported gas jetting from vents on the S side of Pu`u `O`o.
On 10 March, lava stopped flowing at the East Ka`ili`ili ocean entry, possibly due to branching off W towards the Royal Gardens subdivision. `A`a flows from the Campout flow were seen on the pali on 14 and 27 March. During 28-29 March, there was an unusual increase in the number of earthquakes located near the Halema'uma'u and Koko'olau craters and on the S flank. Then on 31 March, a major lava breakout from the Campout flow caused trees to ignite on a nearby island of vegetation and produced small explosion from trapped gas.
Geologic Summary. Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions of Kilauea are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Information Contacts: Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawai'i National Park, HI 96718, USA (URL: http://hvo.wr.usgs.gov/; Email:hvo-info@xxxxxxxxxxxxxxxxxxx).
Global Volcanism Program (http://www.volcano.si.edu/)
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