Ima Itikarai, RVO, on 29 January 2005:
“… it has been a very eventful week … Tavurvur resumed eruption on Monday evening and Manam produced another paroxysmal eruption on Thursday night … . Our observation post at Warisi village was wiped out completely by what is described as pyroclastic flow … . All our equipment was destroyed by the event. There were about 14 people at Warisi at the time of the eruption and all got injured while trying to escape …” (From “Fire Mountains of the Island”)
Although Manam seems to be like any other small island arc volcano, the fact that it is inhabited poses an outstanding challenge to government and volcanologists. And more so to the Manam people who have gone through hell several times already. And no, it is not “their fault” at all.
Manam, called Manam Motu by its residents, or sometimes Mount Iabu, is an island in the Bismarck Sea, 13 km off the NE coast of mainland Papua New Guinea, Bogia District. The Manam People are normally largely self-sufficient in terms of food production. They maintain gardens of vegetables and root crops, keep chickens and go fishing. In 2005, Manam had a population of 10,677 (1880 families in 16 villages).
The volcano is by far the highest in the western half of the Bismarck Volcanic Arc. The circular island is just 11 km wide, and it consists entirely of the 1807 m high stratovolcano.
THE PRESENT ERUPTION
On 25 August 2018, at 6:00 in the morning, Manam erupted an ash cloud of 15 km hight.
More than 2,000 villagers were shocked by the events and had evacuated that day. The villages of Kolang and Dangale have been flooded by a pyroclastic flow. Most other villages have been affected by heavy ash fall. No deaths were reported. Ash fall has also affected neighboring Boisa Island, home to 872 people. Over 5000 men, women and children remained on Manam without clean drinking water and food. Food gardens were destroyed by the ash fall and water sources heavily contaminated. Many houses were flattened, caving in under the weight of volcanic ash.
Manam island can only be accessed using small boats with outboard motors, which are vulnerable to rough seas. Larger vessels have to wait offshore. This puts restraints on supply deliveries or number of people to be evacuated at any one time. – Due to severe communication problems, this eruption was not detected by RVO volcanologists. Steve Saunders (of RVO) stated, it was an unusually large eruption; a new vent had opened, indicating that more activity could be expected after the initial phase. Currently the Manam volcano is at alert level “3”.
The latest weekly from the GVP site says, RVO reported that during 26 August-3 September white plumes rose from Manam’s Main and Southern craters. Seismicity was at low levels. However, on 07 Sept. a thermal anomaly could be seen again on Sentinel 2 thermal images. Also, Darwin VAAC reported a 3.5 km ash cloud that day.
Video published on Aug. 26, 2018. Courtesy Sally Proctor via Storyful (Better turn volume well down!)
Everybody in the news reports or social media talked of a “sudden” or “unexpected” eruption of Manam. Yet, whoever had Internet access could have seen that the volcano was in moderate eruption since at least 13 August, after an earlier period of lower activity since end of July. It needn’t have been unexpected, it had been “gearing up”, so to speak, for quite a while. The explosion on Aug. 25 was just the latest, strongest part of it. So, why was everybody surprised?
VOLCANISM IN THE PLATE COLLISION ZONE
Considerable volcanic activity has taken place throughout history in the Bismarck Volcanic Arc. The eastern part of it (New Britain Arc) is above a subduction zone of the Solomon Sea Plate. This plate dives down below the South Bismarck Sea Plate at rates over 20 cm/year. However, beneath Manam volcano – in the western part of the arc – no active subduction zone, no Benioff zone nor a related submarine trench have been found.
This curious situation is considered to be the result of a Tertiary continent – arc collision: at that time, the anti-clockwise rotation of the Bismarck Sea Plate caused it to slam into the Australian continental plate, pushing up PNG mainland mountain ranges in the process. Below this collision zone at the plate boundary, the previously subducted slab (of Solomon Sea Plate) may be continuing to sink into the mantle underneath. This is concluded from of the analyses of lava samples: their chemical composition has additional mineral components that can only derive from former sea surface sediments.
Manam is a basaltic-andesitic stratovolcano with symmetrical lower flanks. Four pronounced radial valleys arranged almost exactly at 90° angles are churned into its upper parts. These terminate in wide funnels below the summit area and thus channel most (moderate) flows and avalanches towards the coast. On several occasions, though, larger pyroclastic flows spilled considerably over their sides. Manam has two summit craters: Main Crater and South Crater. Both are frequently active. Eruptions from flank vents are also known: five small satellitic cones have been piled up near the island’s shoreline on the N, S and W sides.
Explosive eruptions at Manam have at times been particularly violent, implying massive discharge of gases from the magma in its conduits. Events in 1919 and 2004/5 had been assigned a VEI of 4. The larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea. Also the presently ongoing eruptive episode, that began in 2014, is a VEI 4 so far. Most earlier historical eruptions, though, were typically small to moderate (VEI 1-3) since the first record in 1616. During the previous eruption in April/May 2017 women and children were moved to the mainland. RVO had called an alert level “3”.
DIFFICULTIES OF MONITORING
Particularly large eruptions, for example, had taken place in Oct.-Nov. 1992 and Dec. 1996. The latter eruption had already begun in October, but was not considered a major threat. On the afternoon of 3 Dec. several large PFs descended the SE and SW valleys. One of them reached the coast and killed 13 people at the site of Budua Old Village before flowing into the sea. Neither the start of the 1996 eruption, nor later its violent phases, were anticipated by RVO from the monitoring data from the Tabele observatory.
Up to 2001, signals could be sent by HF-radio from Tabele to the nearby mainland and then on to RVO headquarters in Rabaul. This, however, ended when compensation and access issues were raised by the land owner at the observatory site; subsequently it was vandalised. Then, a smaller, makeshift observatory station equipped with a single seismograph was set up at Warisi village. It had a device for radio-voice reporting from a local observer to Rabaul. This station was very limited in its capacity to cope with, for example, the devastating eruptions of 2004–2005, although RVO staff continued to advise provincial disaster authorities as best as they could.
Tellingly, the last and only mention of “Manam” on the PNG National Disaster Center’s website is from 2016 in a funding related report: a half-sentence mention of the 2004 event.
THE 2004/5 ERUPTION AND TOTAL EVACUATION
Manam has had several strong eruptions during 10/2004-01/2005, and an early warning of their severity was not possible with the inadequate monitoring situation. Towards end of November heavy ash eruptions had been reported. Loud roaring and rumbling noises were heard, and occasional loud and banging noises that produced shock waves. A continuous bright red glow visible down the NE valley indicated emplacement of a lava flow. On 23-24 Nov. 2004 a lava flow was reported to be heading for two of the villages. People had sought shelter in safer places but eventually, heavy scoria & ash fall and pyroclastic flows covered the island in all four sectors.
By late November evacuations had begun, to care centres on the mainland. About 9,500 people were evacuated by 1 Dec. 2004 as the eruption grew ever more violent. On the 6th, residents of Madang (~150 km E of Manam) described feeling tremor or ground motion; those in Wewak (~160 km to the W) reported similar sensations and also noted volcanic dust.
But the most severe and damaging eruption took place on 27 Jan. 2005. That event occurred in good weather conditions, so the Darwin VAAC was able to confirm, via satellite imagery, that the ash cloud reached to 21-24 km altitude, piercing the sky well into the stratosphere. Ashfall was reported ~230 km W of Manam. The next day brought another plume of 18 km hight.
Image left: An infrared Aqua/MODIS image of the umbrella cloud from the 27/01/2005 Manam eruption. The image is enhanced to show the ‘warm spot’ in the centre of the cloud (indicating a substantial overshoot of the cloud top into the warmer stratosphere) and the gravity waves in the cloud. The lobate structure at the fringes of the cloud is similar to other observed umbrella clouds, such as the one from Pinatubo in 1991. At this stage the cloud had a diameter of approximately 180 km. Courtesy of Andrew Tupper.
The observation equipment at Warisi was destroyed. This included loss of a satellite telephone, which had been provided by Qantas Airways to provide a direct telecommunications link between Manam and Qantas HQ in Australia. The Rabaul observatory had been struck by lightning a month earlier, thereby limiting outside telecommunications and adding to the problem of responding effectively to the major disaster on Manam.
“WHY DO THEY NOT ‘JUST’ SETTLE ON THE MAINLAND?”
This question has been frequently asked, and I admit, it occurred to me as well before I started digging somewhat deeper.
When the Manam volcano erupted in the past, islanders from the threatened villages would go over to the mainland to stay with their traditional hosts, who offered food and accommodation until volcanic activity died down. Conditions were different, however, when the volcano erupted in 2004/5. All of the islanders were evacuated at once, and, this time, volcanologists warned the government that the volcano posed an ongoing threat, and that the island was not fit for permanent inhabitation.
People remained stranded, at first even without adequate food, water or shelter until international help efforts kicked in. From then on, the 10 000 who had been evacuated were struggling to survive in those malaria-infested, hastily prepared emergency “care centers” with few facilities.
These care centers were supposed to be just a temporary solution. They were set up on land that was considered traditionally owned by the surrounding peoples. As time wore on and on, social tension and violence erupted between the uninvited IDPs (internally displaced persons) and their coastal neighbours. This worsened when the time of international emergency relief ended and the evacuees were left to fend for themselves. As the Manam population in the care centres had grown over the years, increasing food shortages intensified conflicts over resources. Islanders were looking to obtain building materials for houses, fishing rights and hunt on nearby land. A number of islanders lost their lives through atrocities, and more through illnesses and malnutrition.
After one particularly violent encounter in 2009 between mainlanders and Manam villagers, almost 1000 people were sent back to Manam, where they resettled at their traditional Baliau village site. From that time on, ignoring the volcanic risk, by and by many of the islanders returned to Manam. The others stayed on, and they still live in the “care centers”, maintaining an arduous sort of double-live between their present, unloved place and their home island. Though the government did not care for the people remaining in the care centers, they also did not provide facilities to Manam island, such as education, health care or transportation to and from the mainland.
It has been 14 years since the last great eruption, and the situation has not changed, except that the number of Manam people has likely doubled by now. Some newspapers even mention that there are evacuees from the 1996 eruption still living in the care centers. Over time, resettlement had become a difficult and complex political issue. The government has not managed to provide all of them with a habitable place of their own on the mainland (but, see below). Not only have the Manam Islanders become impoverished materially as a result of their displacement, they have also suffered socially and culturally.
Now, imagine the present situation: Thousands of Manam People still live in the meanwhile dilapidated care centers on the mainland – with no means to better their situation. A new eruption of Manam volcano is underway. Locals on Manam are moving around, from the worst affected places to temporarily safer ones. Yet, they refuse to leave Manam for the mainland and want to remain, despite the considerable risks. Which is perfectly understandable… it doesn’t take much imagination to see what sort of life is awaiting them in more “care” centers.
Things had looked hopeful in 2016. The International Organization for Migration (IOM) was asked by the Government to assist in stabilizing the IDP and host communities as well as supporting the longer term resettlement process. The IOM had managed to get all involved parties at one table “to mitigate conflict and unite the tribes through joint development initiatives”. Plans had been made, promises been given… It seems though, that to this day no sustainable solution has been found for these people.
Things look hopeful again in 2018… on 3 Sept., PM O’Neill said that the “Manam Bill” had been passed and implemented. There should not be any more delays in resettling the now more than 20,000 islanders. He would see to it.
Throughout Melanesia, and the wider Pacific, similar cases have been reported. Resettlement has always been contested, sometimes violently, by the local customary landowners. Tensions are rising as land comes under greater commercial pressure. Land is now seen as too valuable for displaced people to lease or purchase. With weather patterns changing worldwide and subsequent sea level rise, with volcanoes or other threats making islands inhabitable, there will be many more occasions where new concepts of resettlement will be needed.
Disclaimer: I am not a scientist, all information in this (and any of my other posts) is gleaned from the www and/or from books I have read, so hopefully from people who do get things right! 🙂 If you find something not quite right, or if you can add some more interesting stuff, please leave a comment.
Enjoy! – GRANYIA
SOURCES & FURTHER READING
– GVP, Manam
– Manam Island: Petrology and Geochemistry […] (1985, paywalled)
– Environmental Refugees? A tale of […] (2017, paywalled)
– Fire Mountains of the Islands (Book, online)
– Rapid magmatic processes accompany arc–continent collision: the Western Bismarck arc (2012, paywalled)
– My Land, My Country (Scott Waide’s blog)
– Needs assessment briefing note 09/2018
– Born of Mountain Fire (IOM feature)
– Reporting by “Loop” PNG newspaper
– Reporting on Manam by The National