A lava flow was active on the lower E flank of the volcano; its source was apparently a radial fissure about 500 m long, some 6 km from the summit and 2,000 m vertically below it, along which a number of individual lava vents could be seen. According to a news source (Radio New Zealand, flights in and out of Hoskins airport in Port Moresby were cancelled on 4 August due to tephra fall. No incandescence was visible. Seismic activity remained at low levels. "An aerial inspection on the 29th gave the first clear view of the base of the crater. Emissions in June consisted of thin white vapor. "Summit activity during the night of 9-10 May was reduced in comparison to that of the previous nights, with much less incandescence, and intermittent spells of inactivity up to 30 seconds long. Information Contacts: Ima Itikarai, Rabaul Volcano Observatory (RVO), P.O. Steam plumes (with some possible ash) in February 2010. Dense, gray-brown ash plumes continued to rise to 200 m during 1-7 December. 2010 Activity
Seismic activity continued at low levels with low-frequency earthquakes recorded. Two classrooms at the Navo Primary School and a church in Navo collapsed from the weight of the ash and scoria; one of the classroom roofs had already partially collapsed during the 26 June eruption. A deflationary trend continued to be detected. Some discrete high-frequency volcanic earthquakes were also recorded on most days. Information Contacts: P. de Saint-Ours and C. McKee, RVO. | September
Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea. On 31 May, a thin steam-and-ash plume from Ulawun reached an altitude of below 3 km (10,000 ft) a.s.l. A thin steam-and-ash plume reached an altitude of below 3 km. The mountain was obscured on most days and received very heavy rainfall between the 9th and the end of the month. No sounds or night glow were reported. Seismic activity remained at a very low level.". A Post Courier news article stated that the eruption began at 0230 on 29 September, but due to communication problems with the Rabaul Volcano Observatory's Mount Ulamona monitoring station they did not receive reports of the eruption until about 0800. "During an aerial inspection on 7 September, a pool of fluid lava was observed in the bottom of the summit crater, about 50-100 m below the rim; explosions took place from a small circular central vent. Some of the VT earthquakes were felt, including three on 30 June. The plumes rose 1 km and caused minor ashfall to the NW and SW. Local residents heard roaring and rumbling during 0600-0800. Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. . During the cover of darkness, ash clouds were just visible, initially illuminated by the glow and gradually by incandescent fragments. Based on satellite imagery, the Darwin VAAC reported a diffuse ash-and-steam plume from Ulawun on 29 November and an ash plume on 4 December. Steam-and-ash plumes reached altitudes of 3.7 km and drifted NW. Ash plumes from Ulawun during January-November 2017, based upon analyses of satellite imagery. A small landslide scar appeared near the N valley flank vent, reportedly caused by movement of a large boulder and loose material, triggered by a M 6.1 earthquake that occurred near Pomio (55 km SSE) on 19 November. The Strombolian activity lasted about an hour. On 27 and 28 March light gray emissions were observed, and small continuous volcanic tremor was recorded for six hours. Volcano seismicity was low, with daily totals of 20-30 recorded events.". Volcanic seismicity was low, with several strongly felt tectonic earthquakes on the night of 3-4 July. Mount Ulawun volcano erupts with hot ash and lava sent flying into the sky; ... 62, looks the same as she did 30 years ago when she was in Last Of The Mohicans as … Ashfall was again reported in Ulamona on 8 June. "No unusual visible activity directly accompanied the seismic crisis. A brief interval of low amplitudes followed the crisis of 17-18 June, but a steady rise in amplitudes was recorded beginning 20 June. RVO staff in Rabaul established communication links with the volcano observer based near Ulawun at 1606 on 27 September after noting increased RSAM values. Weak, fluctuating incandescence was observed on 22 May. During the eruption, visible activity often coincided with regular periods of low-amplitude, high-frequency tremor. A large grey plume with weak red glow was observed on the nights of 5, 6, and 9 March. A small pit crater was present near the SW edge of the summit crater. Ash emissions began on 11 June and then became dense during 21-23 June. Volcanic earthquakes increase; vapor emission. Seismicity was low during 1-6 May, consisting of discrete, low-frequency earthquakes. The only break in activity was in February, March, and the first part of April. The areas most affected by ash and scoria fall were between Navo (W) and Saltamana Estate (NW). The summit crater released a low-pressure, sulfur-laden vapour plume, and daily seismicity included fewer than 1,000 B-type recorded events. 2012: May
The readings on these days showed that little or no tilting was occurring. Incandescent lava fragments (visible in the early morning) and other rock material from the intense activity rolled almost a third of the way down the slopes. "The ground deformation network (EDM and dry tilt) was reoccupied 2-4 May. The summit crater released white vapours in weak to moderate volume on most days. Long steam plumes during 22-23 August 2004 (BGVN 29:07) were observed on satellite imagery. Information Contacts: I. Itikarai, P. de Saint-Ours, and C. McKee, RVO. On 15 March a faint plume was visible on satellite imagery. The summit was obscured throughout most of the period of increased seismicity. "Aerial inspections the following morning showed powerful ejections of red incandescent bombs every few seconds, feeding an eruption column 1-1.5 km high. Loose ash was stirred up by the flow and produced an 'eruption-like' plume. RVO reported that during 1-20 May Ulawun emitted variable amounts of white vapor. Volcanism on 25 April consisted of a steady weak red glow, occasional rumbling noises, and thick ash clouds. Between late May and early July, low roaring or rumbling noises often were reported. Beginning 14 November, daily totals of B-type events averaged about 600, a marked increase from daily totals that usually numbered less than 50, 14 September-8 November. ", Low-level seismicity; weak vapor emissions, "Ulawun remained at non-eruptive levels of activity with emissions restricted to weak white vapour. A small landslide scar appeared near the N valley flank vent, reportedly caused by a large bolder and loose material sliding, triggered by a M 6.1 earthquake centered near Pomio (55 km SSE) on 19 November. The Darwin VAAC reported that a possible low-level ash plume was visible on satellite imagery on 14 April. From 9 January, seismicity declined steadily, and nighttime incandescence from the crater was absent. . Summit activity was very low and consisted of variable amounts of white vapor. During 2-3 July occasional roaring noises were reported. Weak and fluctuating incandescence was seen at night during 28-29 May by people on the S part of the island. Some large and unusual events were recorded on the 9th and l0th that may be volcanic, but their interpretation is unclear at present.". | June
There had been no reports of anomalous volcanic activity at Ulawun since the 28 September-2 October 2000 eruption sent an ash cloud 12-15 km above the volcano (BGVN 25:11). Possible plume evident on 13/2032Z, 13/2132Z and 13/2225Z [images], height estimated below 3 km. RVO reported that during 1-12 October white and sometimes light gray emissions rose from Ulawun’s summit crater. A plume 5-10 km long was formed by the emissions.". Commencing at about 1000, the crisis consisted first of continuous tremor which lasted for about 7 hours. | September
Based on satellite imagery, the Darwin VAAC reported a diffuse plume from Ulawun on 22 November and an ash-and-steam plume on 28 November. ash plume was visible on satellite imagery, extending to the NW. In June, RVO reported that the electronic tiltmeter continued to show long-term deflation of the summit area, but the amount of change was smaller than in the previous 1-3 months. Rothery and Charlotte Saunders provided updates to 31 May 2004. Increasing seismicity then tephra ejection & lava flow. Fisher N H, 1957. The plumes appeared white-gray on occasions and were unusually strong bluish white gray over the last three days of the period. Similar conditions continued through the end of 2007 with only minor incidental variation. "The first sign of any abnormal visible activity was on 12 January, when a report was received of a dark eruption column that was forcefully emitted to ~1,000 m above the summit before declining to 400 m in height and becoming lighter coloured. The eruption column continued to be fed by apparently frequent explosions in the crater but only slight upward growth was evident. Explosive roaring and rumbling noises stopped at about 2200 on 29 September and projections of incandescent lava fragments began to subside at about the same time. and drifted NW, W, and NE. On 25 May, the Darwin VAAC reported a thin steam-and-ash plume from Ulawun that extended 30 miles WNW. St. Helens which killed 57 people and hurled volcanic ash around the world. Ash fell on the NW flanks, in Ubili and Ulamona. By 0230 on 30 September, strong discharges had already stopped and glow at the summit had ceased. The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Reported plumes did not attain an altitude of over 4 km except on 12 November, when they reached an altitude of 4.6 km. Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 25 September a minor ash plume from Ulawun rose 3 km (10,000 ft) a.s.l. Ash from earlier ejections continued to drift S at an altitude of 13.4 km and W at an altitude of 8.5 km. According to RVO, the mild activity that began in May 2010 continued during 1 January-28 February 2011. On the 8th and 11th there followed peaks of over 20 units. Some traces of blue vapor were also visible, but no glow was observed. The ash clouds began to become voluminous from 0100 on the 29th, coinciding with the intensification of the Strombolian phase of the eruption. A small number of local high-frequency earthquakes continued to be recorded, although the rate declined during the month. "A change in visible activity was evident from 9 January when the emissions became rich in white vapour, and ash ejections were less frequent. Seismicity was mainly characterized by bands of low-amplitude, high-frequency, harmonic tremor. It consisted of several periods of tremor up to 13 hours long, and sub-continuous volcanic earthquakes. The Alert Level was raised to Stage 3 (the second highest level on a four-stage scale). This pattern of seismicity had begun on 26 October 1988. On some days, emissions appeared to contain ash. This report describes activity between January and September 2018. On 25 April, Ulawun began what appeared to ground-based observers as a relatively small eruption that lasted about 6 days (ending the 30th). After that the values declined again to 300, and fluctuated between 250 and 350 until the end of the month. Slightly stronger emissions occurred on 17 and 26 January. Eruption on 29 September causes the evacuation of nearby towns. The plume extended toward the NW. Source: Rabaul Volcano Observatory (RVO) via the Darwin Volcanic Ash Advisory Center. However, aerial inspections in 1985 and 1993 only revealed evidence of Vent A. Ulawun had a flank eruption on the SE side during the 1978 eruption. When visible, weak-moderate white vapour emissions were observed. During the night of 2-3 August crater incandescence strengthened and roaring noises became louder around 0400. Low-level seismicity continued. RVO recommended that the Alert Level be reduced to Stage 2. During 23-26 February, gray ash plumes occasionally drifted NE, SW, and NW. In relatively clear morning weather, the eruption column was visible from Rabaul, ~130 km NE of Ulawun. Plumes at and Manam were strong, and plume was small.
. The plume was larger than normal (about 300 m high) and extended 5-10 km from the summit. Based on satellite imagery, the Darwin VAAC reported that ash-and-steam plumes from Ulawun drifted SW and S on 30 August and 2 September, respectively. Assistance was later provided by the West New Britain Provincial Government. Tectonic plates, extreme weather, magma movements and even the effects of climate change can all play a role in triggering volcanic eruptions, writes Ariella Heffernan-Marks The cloud reached an altitude of ~9 km and drifted NW and SW, expanding to 80-113 km in radius. Thin ash plume to 4 km moving to the W at 10 knots [10 NM/hour or 18 km/hour]. Reference. Deployment of a portable seismograph during 13-15 August indicated these earthquakes had epicenters at Ulawun. Intermittent ash plumes during eruptive periods in May 2012, November-December 2012, July-December 2013, and October-November 2016. Air Niugini pilot David Innes noted on 23 August that he had flown past Uluwan early the previous week and noted what appeared to be steam and light 'smoke,' but did not note any ash. Included in the tremor were discrete B-type events. The summit crater emitted white and blue vapours in weak to moderate amounts. No noise or night-time glow was reported during the month. On the 30th, an Ms 5 regional earthquake, 75 km away, triggered continuous tremor lasting the following 2 1/2 days. . A small low-level plume emitted from Ulawun was visible on satellite imagery extending W on 9 April. Unlike some of its perpetually active neighbors on the Kamchatka Peninsula, Raikoke Volcano on the Kuril Islands rarely erupts. Data from Ulawun were transmitted to RVO every 20 minutes. Based on observations of satellite imagery, the Darwin VAAC reported that an ash-and-steam plume from Ulawun drifted W on 25 December. RVO reported that on most days during 16-30 November small volumes of gray to gray-brown ash plumes rose 100 m from the crater and drifted S. On 21 November ashfall was reported in Navo on the SW flank. Summit crater emissions consisted of white vapours released at low to moderate rates. J. Volcanol. Highlights of behavior, August 2010 through February 2011. "Seismic activity began to increase on 12 November with the occasional appearance of small discrete B-type volcanic earthquakes. There is data available for 46 Holocene eruptive periods. A check of MODVOLC thermal alerts in mid-April 2010 found no anomalies for Ulawun as far back as May 2001. The lava-flow rate slowed to 3-5 m a day, likely because it was no longer being fed. This activity waned after a week and by the end of the month was at a low level, with earthquake counts of <30/day. As of 5 October activity had declined and was relatively stable, but the evacuation orders were still in effect. During 23-26 February gray ash plumes occasionally drifted NE, SW, and NW. Ash emissions occurred 6, 8, 11, 20-22, and 28 April, but their ash content was low, and no significant ashfalls were reported. The sub-continuous showering of explosion debris around the crater built up an apron of highly unstable material.
The plume then detached and drifted S and then SE. RVO reported diffuse gray plumes that rose 200-500 m above Ulawun during 16-21 July 2010. Despite their increase in number, there was no marked increase in amplitude. Based on analyses of satellite imagery, the Darwin VAAC reported that on 7 November an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. The most recent eruption began in late June 2019 involving ash and gas-and-steam emissions, increased seismicity, and a pyroclastic flow (BGVN 44:09). Weak, fluctuating incandescence was observed on 22 May. By the following day the anomaly had increased in spatial dimension to eight alert-pixels although the maximum alert ratio was lower (-0.224). Seismicity remained low until 27-29 October; it increased again and peaked on 30 October, reaching an RSAM value of 1,700 before dropping and fluctuating around 1,200-1,500. On the morning of 31 January the seismicity suddenly changed to distinct B-type events. Fluctuating incandescence from the crater was observed at night during 28-29 May, 6-10 June, 13 June, and 16-25 June. Earthquakes such as these were rare before the build-up to the September eruption, but they have continued since then. Emissions from the summit crater consisted of white vapor during 1-7 July, and then changed to occasionally sub-continuous, light gray ash clouds during 8 and 11-14 July. During this time local residents heard booming. | April
The behavior could possibly be related to edifice inflation. The quoted material is a report from RVO, with additional information on SO2 flux supplied by S. Williams. Rabaul town (E) also reported ashfall. These stated that during 1130-1155 ash plumes rose to 6.7-8.5 km (22,000-28,000 ft) a.s.l. Very light ashfall was reported from Sule and Nuau. | September
Geological Survey of Papua New Guinea. During the first half of the month emissions from the summit crater were moderate to strong, consisting of thick white vapour. RVO recommended a Stage 1 Alert as a result of increasing seismicity and occasional gray plumes, incandescence, and audible noises. The visible commencement of the eruption was late at night on 6 October. | December
Heavy rains during February and especially on the 19th, 21st, 22nd, and 24th, caused debris flows on the NW side of Ulawun. Based on recent observations, activity at Ulawun is expected to remain low. Reports from Diego Coppola and David A. Rothery provided analyses of MODIS thermal alerts during 2001 and 2002 (using the MODVOLC alert-detection algorithm) extracted from the MODIS Thermal Alerts website (http://modis.hgip.hawaii.edu/) maintained by the University of Hawaii HIGP MODIS Thermal Alerts team (BGVN 28:01). Courtesy of Darwin VAAC. During the rest of August, the summit crater released thick white vapor. Ash clouds blew NW dropping very fine ash. Residents between Sena Estate and Noau on the N flank reported ashfall in early December. . The MIROVA (Middle InfraRed Observation of Volcanic Activity) system detected three anomalies during the reporting period, one during the last week of June 2019 and two during the first week of August, all three within 3 km of the volcano and of low to moderate energy. Seismicity remained at a low level throughout the month.". RSAM values increased and by mid-October were at the highest values (peak of 200) so far in 2016. Seismicity returned to background levels after volcanic tremors ceased on 18 March 2002. RSAM increased from about 0700 on 14 July onwards with the emergence of continuous volcanic tremors until it reached a peak of 700 just after 0300 on 15 July. No additional activity was reported by the Rabaul Volcano Observatory (RVO) until a seismic swarm preceded observations of glow on 13-14 June 2008. Further Reference. Seismicity during 31 January-2 February was characterized by B-type volcanic events, which occurred at irregular intervals. This had some of the characteristics of both nuées ardentes and lava flows, to judge by the descriptions, and the mountain was [reported] to have split from top to bottom. This rapidly developed into explosions of incandescent lava fragments from the summit crater, which increased in intensity until by 2100-2200 a full-scale eruption was in progress. Seismicity was low (and dominated by small low-frequency earthquakes) although RSAM values slowly increased and then spiked on 13 June. RVO reported that during 23-27 May gray ash plumes rose above Ulawun's summit crater. An eruption did take place, observed by a group of people staying nearby and who sent us images on social media, but it was “only” producing an ash column rising approx. A temporary increase in seismicity was recorded between 11 and 20 February 1991. The lava flow slowed, advancing 3-5 m/day, while declining seismicity was reflected in RSAM values fluctuating around 1,000. Information Contacts: C. McKee, H. Patia, and P. de Saint-Ours, RVO. Tremor rapidly became strong and continuous. It covers the new flank-vent eruption and its preceding events. Intermittent ash plumes from August through early November 2002.
Moderate to occasionally strong, white-grey emissions were released from the summit crater. Low level plume detected on visible satellite imagery at 18/2100Z. | September
The volcano, also known as the Father, rises above the N coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. By 3 October the volcano produced only thin white vapor with no noise or night glow. "An explosion sound from Ulawun was reported on 4 March, and tephra emissions were observed on the 5th and 13th. and drifted over 45 km E. Based on analyses of satellite imagery, the Darwin VAAC reported that during 26-28 October ash plumes from Ulawun rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. "It is interesting to note that the high level of seismicity closely followed a heavy rainfall of 65 mm. Fine ashfall was reported almost daily and affected the NW, W, and SW flanks. Gray emissions were also reportedly observed on three days in October and a number of days in November.
The plume then detached and drifted S and then SE. Satellite imagery for 2 May indicated an ash-and-steam plume rising to ~4 km and blowing W at ~30 km/hour. There is data available for 5 emission periods. During the past 6.5 years, through September 1999, summit activity at Ulawun consisted of variable amounts of emissions that ranged from very thin white vapor to moderate volumes of thick white vapor. By dawn light-gray ash plumes were visible rising several hundred meters and drifting NW. After 22 February tremor returned to background levels. Information Contacts: N. LauerR. The RSAM values reflect an increase in seismicity dominated by volcanic tremor. The level of tremor increased by a factor of about two between 0300 and 0400 on 20 January. On 9 August a plume drifting to the S was visible on satellite imagery (figure 10). An eruption in 1980 ejected ash to 60,000 ft and produced pyroclastic flows which swept all flanks of the volcano and devastated an area of 20 sq km. 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