1951 eruption of Mount Lamington

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1951 eruption of Mount Lamington
Mount Lamington devastation.jpg
The force of the blast left a Jeep hanging on the remains of a tree
VolcanoMount Lamington
Start dateJanuary 17, 1951 (1951-01-17)
Start time10:40 PGT
End dateJuly 2, 1956 (1956-07-02)
TypePlinian, Peléan and Vulcanian
LocationOro Province, Territory of Papua and New Guinea (present-day Papua New Guinea)
8°57′S 148°09′E / 8.95°S 148.15°E / -8.95; 148.15Coordinates: 8°57′S 148°09′E / 8.95°S 148.15°E / -8.95; 148.15
VEI4
Deaths2,942–3,466
Mt. Lamington is located in Papua New Guinea
Mt. Lamington
Mt. Lamington

In early January 1951, a series of minor explosions and earthquakes rocked Mount Lamington, a volcano in Oro Province, Territory of Papua and New Guinea. Prior to the eruption, Mount Lamington was not recognized as a volcano due to the absence of historically-recorded eruptions and dense vegetation cover. From January 15, volcanic activity intensified, and tall eruption plumes were generated. The largest eruption occurred on the morning of January 21 when a thick black plume of ash rose 50,000 feet (15,000 m) into the atmosphere.[1] The eruption collapsed a lava dome and produced a lethal pyroclastic flow that killed 2,942–3,466 people. In the years after the eruption, new lava domes formed and collapsed in succession. Activity persisted until July 1956. The eruption is the deadliest natural disaster in Australian history, as the region was under the rule of the Government of Australia.

Tectonic setting

Volcanism in Papua New Guinea is due to the ongoing subduction of oceanic crust beneath the island due to plate tectonics. Mount Lamington is situated within the Hydrographers Range; a small, forested coastal mountain range. The mountain range is the remnant of a heavily eroded Quaternary stratovolcano. The dominant rock types are andesite and basaltic andesite. While a majority of the range's eruptive history occurred during the Pleistocene, the presence of cinder cones and craters on the southern flank of the range suggest volcanism also took place during the Holocene. The mountain lies adjacent to the Owen Stanley Range. Nearby volcanoes include Mount Suckling and Mount Victory.[2]

Mount Lamington rises to a height of 1,680 meters above the coastal flats north of the Owen Stanley Range. A summit complex of lava domes and crater remnants rises above a low-angle base of volcaniclastic deposits that are dissected by radial valleys. A prominent broad "avalanche valley" extends northward from the breached crater.[3] The horseshoe-shaped crater was the result of a large prehistoric sector collapse.[4]

Eruptive history

Prior to the eruption in 1951, Mount Lamington was not known by locals to be an active volcano as no ancient folklore or stories of the volcano existed among the native population. The only indication of volcanic activity was a small hot spring on the northern slopes, which was not known by most of the native population.[2] There were also settlements located on the flank of the volcano. The only traditional story related to the volcano's activity was of a lake on the summit which exploded, destroying villages and killing many people. The native population regards the mountain as a sacred and spiritual place.[5]

Geologists however, understood that Mount Lamington and the Hydrographers Range were volcanic in origin, and that it was a geologically young feature. A geologist from the Netherlands classified Mount Lamington an active volcano.[6] Only three eruptions were confirmed in the Holocene.[2]

Descriptions

A map of Mount Lamington and its surroundings from 1962

A number of inhabitants around Mount Lamington reported earthquakes in early January 1951. One eyewitness also saw a strange light on New Year's Day of 1951.[7]

On the morning of January 15, residents saw evidence of landslides in the crater wall of the volcano. Landslide scars identified as streaks of brown in the heavily forested volcano flank indicated the volcano was active. At a rubber plantation in Sangara, a village, a person reported a white smoke or vapour cloud rising from the base of the volcano. Around the crater, vegetation was killed due to the intense heat of the ground.[7]

The following day, January 16, a vapour cloud was seen from Higaturu. Large landslides were reported, many destroying the existing vegetation. The entire rainforest around the crater was destroyed by the late afternoon. An earthquake swarm also occurred at 16:00. Up to 30 earthquakes were felt till 08:00 on January 17. Stronger earthquakes were felt in Isivita Mission, located northwest of the crater.[8]

On January 17, an ash column rising between some hills and Mount Lamington was observed. The column grew larger as the hours passed. Earthquakes continued to be felt, and there was a red glow observed at night. By January 18, large plumes of dark grey ash ejected from the volcano. A large explosion occurred in the morning. A newly-constructed volcanic hill where volcanic material escaped was observed. The eruptions did not cause any human deaths, according to District Commissioner Cecil Cowley on January 19. Large columns of ash rising 20,000–25,000 feet (6,100–7,600 m) could be observed from Popondetta.[9]

The eruption column was 25,000–30,000 feet in height by January 20. From Kokoda, the eruption was described as a large black column, and had a shape reminiscent of a cauliflower. Monsoon winds caused heavy ashfall on the southern side of the volcano. Some settlements where the Orokaiva people lived were damaged.[10]

January 21 eruption

The most violent eruption occurred four days later at 10:40 local time. Occupants on two Qantas Empire Airways flights which flew in close proximity to the erupting volcano reported a large eruption column and base surge of pyroclastic debris. The captain of a Douglas DC3 flight witnessed a massive continuous column of black smoke erupting from the crater. The column rose over 14,000 feet (4,300 m), punching through a layer of clouds. In two minutes, the column had risen 40,000 feet (12,000 m) from the crater, and expanded into a mushroom column. The eruption column reached 50,000 feet at its highest.[11] The captain of the DC 3 radioed authorities at Port Moresby about the sequence of events. Another Qantas flight; a de Havilland Dragon bound for Popondetta from Lae, was about to land when its occupants witnessed the side of volcano blow itself apart. A large surge of debris approached the aircraft, forcing its return to Lae.

Changing winds caused the pyroclastic surge to direct northeast, where it was seen at Kokoda. Lightning activity was observed in the eruption column. Ash, pumice and small rocks fell to the ground. The eruption column was also observed at Eroro, where many residents mistook it for a petrol explosion at Higaturu. A large pyroclastic surge raced towards Isivita Mission; 75 kilometres (47 mi) northwest of the crater. Many panicked residents rushed to the main mission house. The flow however, ceased in the mission compound. A definitive boundary between the grassy field and thick layer of volcanic material marked the trail of the flow. By 11:30, the eruption column had blocked out sunlight. Thunder was heard, and intense lightnings were observed.[11]

Awala Plantation near Isivita Mission was spared the worst of the eruption but suffered from extensive ash fall. Much of the rubber, coffee and cocoa crops were devastated. The loss of crops had implications for the local economy. The eruption seriously affected the fish population in rivers. The local population experienced a decline in the aftermath of the eruption. Rainforests were also covered in thick layers of ash, and trees began to topple or break apart due to the weight of ash.[11] Overnight, 18 people perished at Isivita. Despite being closer to the volcano, Higaturu, another town slightly further away, was totally destroyed.

By the afternoon, many residents with extreme burns from the pyroclastic flow were rescued. Many began to arrive at treatment centers for medical assistance. Survivors described the sounds of agony from burn victims. Some victims experienced total burns to their skins. One burn victim later died. More deaths were anticipated following the eruption, so a large grave was dug. There was a large inflow of seriously burnt victims at the Sangara Plantation. Injured victims were also transported to Popondetta.[11]

The destruction was described as "complete" and compared to a bomb explosion. Trees in the dense tropical rainforest toppled or were pulverized. Nearly every building was decimated by the flow. The region surrounding Mount Lamington was transformed into a moonscape-like environment. Charred bodies of people attempting to flee the surging flow littered the roads.[6]

As close as 3 kilometres (1.9 mi) from the crater, some areas of rainforest were charred. In the areas where charring occurred, the pyroclastic flow was extremely dense. This allowed the flows to retain its extreme temperatures and also cause severe scraping in the ground. Hundreds were fatally burnt at Higaturu from the heat of the pyroclastic flows. However, the temperatures were not sufficient for wood to combust and thermally decompose. In one house at Higaturu, a cotton reel and drive belt from a sewing machine remained unaffected. In another house, a plastic lampshade melted and collapsed. Two unburnt violins were also found at a residence.[12] Volcanologist Tony Taylor analyzed penicillin discovered at a hospital and determined that the area experienced temperatures of up to 200 °C for a period of 1.5–2 minutes.[13]

Only one house remained intact at Higaturu; the rest were obliterated, leaving only the floors intact. A previously straight steel pole on the hospital was severely bent in two places, and one side of it was eroded by the dense cloud. The discovery of a jeep hanging on the remains of a tree suggested vortices formed within the dense flow. Debris were picked up and flung into structures, causing damage. Tony Taylor concluded that winds inside the flow reached 75 mph (121 km/h).[13]

Volcanic activity

Mount Lamington seen from the north in late 1951

The eruption rated a 4 on the Volcanic Explosivity Index (VEI) scale.[3]

Volcanologist Tony Taylor interpreted that the landslides initially observed were the result of the earthquake swarm or other geological processes.[13] Intense activity occurred in the subsequent days after, including an interpreted vulcanian eruption on the 17th. That eruption was caused by magma interacting with groundwater. The young hill structure observed via a telescope was initially interpreted by Taylor as a pile of debris, but a recent analysis of eyewitness reports suggest it was a small lava dome.[4]

On January 21, a large volume of volcanic ash and debris was ejected vertically into the atmosphere in a Plinian eruption style. This vertical eruption blast was accompanied by the lateral collapse of the volcano flank.[4] Prior to the collapse of the flank, the volcano was approximately 2,500 metres (8,200 ft) in elevation. A 1,060-metre (3,480 ft) section of the volcanic cone was destroyed by the collapse. This triggered a debris avalanche only recently discovered, with an estimated volume of 0.02–0.04 km (0.012–0.025 mi)3. A travel distance of 8.5 kilometres (5.3 mi) was measured. The eruption column formed a large mushroom cloud towering over the summit. Pyroclastic flows surged down the flank of the volcano as the eruption column collapsed. The thick and dense cloud of black ash was described as "like toothpaste from a tube".[13] An approximately 230 km (140 mi)2 area of dense tropical rainforest around Mount Lamington was devastated.

The pyroclastic flows moved with such a velocity that no humans in the areas of devastation survived. Extreme damage occurred around a 12 km (7.5 mi) radius around the volcano.[3] The estimated speed of the flow was 135 km/h; twice that of the de Havilland Dragon Qantas flight. It traveled northwards for a distance of 13 km (8.1 mi); due to the influence of the breached, horseshoe crater in the north. A second eruption occurred on the evening at 19:30, generating an ash cloud almost the same height as the daytime eruption. This eruption produced a loud sound and caused heavy ashfall, although no pyroclastic flows were reported.[4]

The post-January 21 eruptive phase consisted of explosive eruptions which produced pyroclastic flows. A large pyroclastic flow was documented on March 5, 1951. After the climactic eruption on January 21, a new lava dome formed in the crater. The new lava dome grew to fill the crater. From 1951 to 1953, new lava domes formed and collapsed, generating more pyroclastic flows. The dome eventually attained a height of 450 meters from the crater floor to its summit and had a volume of 0.2 km (0.12 mi)3.[4]

Casualties

The eruption resulted in the deaths of between 2,942 and 3,466 people.[14] It left a further 5,000 homeless.[15] The majority of those killed resided in the village of Sangara, part of a large preliterate society referred by colonial powers as the Orokaiva people.[16] Only 35 'white' Australian expatriates were killed in the eruption: 14 bodies were discovered two years after the eruption.[16] Deaths as a direct effect of the pyroclastic flows were similar to those observed after the 1902 eruption of Mount Pelée and La Soufrière. The ingestion of hot volcanic material caused the respiratory system of its victims to swell, exfoliate, and eventually rupture. Fatal asphyxiation was also suggested by the conditions of the victims' bodies. Rigor mortis was observed in the bodies, many in a sitting or kneeling position due to thermal-induced muscle stiffness. The intact bodies suggests victims did not die from flying objects or collapsed structures.[12]

At the refugee centers, poor hygiene led to health issues, and three people ended up dying, including a child who succumbed to pneumonia.[12] Initially, 40 people were found alive and brought to a hospital, but 22 died within 24 hours.[1] It is unknown how many more people underwent psychological distress from the disaster as no counselling services were provided.[17] Anthropologist Marie Reay who was among the survivors experienced a mental breakdown in 1952 and was hospitalized. Some schoolchildren also struggled with grief after the disaster. An Orokaiva woman died from suicide after finding the remains of her husband and child following the eruption.[17]

Survivors

There were a number of people who were severely burnt but survived the pyroclastic surge. Near the village of Amonikiarota, a woman suffered burns by the tiny particles of lava that struck her skin. The thin cotton dress she wore had shielded much of her body from the advancing hot clouds. Some furry animals including a puppy and mouse also survived.[14]

One native man and two others attempted to flee the eruption along the Ambogo river, but the pyroclastic flow knocked them into the river. After being knocked unconscious for a moment, he was able to recover. When he resurfaced and attempted to breathe, his throat was burned. He sank into the river just when the highest temperatures of the surging flow were passing above and resurfaced later. Of the three, only the man survived (initially two, but one died from her injuries).[14]

Response

Very little was done in preparation for the eruption on January 21. Despite the precursor events of 15–17 January, not much is known if news of the events were sent to administration headquarters in Port Moresby. At the time of the disaster, there had not been a government to handle volcanic disaster; hence, there was no evacuation plan for the regions around Mount Lamington. District Commissioner Cecil Cowley requested the authorities in Port Moresby and, a volcanologist to examine the situation, but his requests were never answered. Volcanologist Tony Taylor said that despite the intense activity leading up to the eruption, authorities were incapable of interpreting them as warning signs and managing the crisis.[11]

Aftermath

Popondetta was the center of relief efforts in the aftermath of the eruption, photographed in 1968.

The government in Port Moresby was briefed of the disaster on the morning of January 22. A relief and recovery mission was established in response. Aircraft delivered excess food, tents, medical and other supplies to the affected regions effectively. At Lae, the Huon, an administrative ship, sailed overnight with medical staff and emergency needs to Popondetta. Rescuers found very few survivors in the affected area; there were more dead bodies being recovered. Airlift operations took place at Popondetta to transport the injured to Port Moresby for treatment. Displaced residents were relocated to refugee camps where they were provided with basic needs.[18]

An undamaged road linking Gona to Kokoda which runs north of Mount Lamington served an important role in the rescue and recovery process. The road helped with the mobilization of injured victims, emergency responders and evacuees. Volcanic ashfall continued to disrupt response operations in the hours that came. Another nighttime eruption that same day caused panic. Ash from the eruptions fell in Port Moresby, forcing the airport to cease operations until the following morning.[6]

At the time of the eruption, Tony Taylor was studying the Rabaul caldera, another volcano in Papua New Guinea. He arrived one day after the eruption. Taylor conducted a dangerous on-site investigation to determine the probability of another eruption, including a flight over the erupting crater.[19]

Two RAAF C-47 Dakota were deployed by the Australian government to assist in the response. The Australian Red Cross also donated blood plasma for injured victims which was transported by the planes. Food, medical supplies and basic needs were delivered by the two aircraft. A de Havilland Mosquito of the No. 87 Squadron RAAF conducted a reconnaissance flight in the affected area.[19]

Regrowth of vegetation

See also: Southeastern Papuan rain forests

Vegetation quickly blossomed as volcanic activity began to decrease. The orange-yellow Neurospora fungus was discovered in the pyroclastic deposit zone three days after the eruption. The subjection of its ascospores momentarily to high temperatures resulted in a booming population. Over a period of six weeks, the fungus population declined until it was a rarity. Occasionally, they appeared on logs that were buried under ash and debris.[18]

Plants that were cultivated by the local population also survived the devastation. The severely damaged coffee and rubber tree plantations regrew and were eventually sufficient to sustain the native population. Tubers were the first plants to appear. It was followed by native grasses and the rainforest trees. Less than a week after the eruption, taro plants began blossoming in some villages. Root vegetables including yam and sweet potato, as well as banana plants started to grow two months later. The regrowth became an important source of food for the population.[20]

Grasses began to cover the mountainside by early 1952. Erosion on the mountain stripped away some of the new ash layer, revealing the pre-eruption soil. The regrowth of trees occurred around this period, and by the end of the year, some were 15 feet (4.6 m) high. The volcanic crater became increasingly inaccessible due to the tall grasses and dense vegetation. There were no vegetation on the smouldering lava dome until 1953 when grasses began to appear.[20]

Memorial

The Mount Lamington Memorial Cemetery opened on November 24, 1952 by the Australian colonial government.[18]

See also

Notes

Citations
  1. ^ a b National Geophysical Data Center / World Data Service (NGDC/WDS) (1972), Global Significant Volcanic Eruptions Database (Data Set), National Geophysical Data Center, NOAA, doi:10.7289/V5JW8BSH
  2. ^ a b c Taylor 1958, p. 11–18.
  3. ^ a b c "Lamington". Global Volcanism Program. Smithsonian Institution. Retrieved 2022-01-23.
  4. ^ a b c d e Belousov et al. 2020.
  5. ^ Johnson 2013, p. 149–171.
  6. ^ a b c Johnson 2013, p. 151–154.
  7. ^ a b Johnson 2020, p. 91–92.
  8. ^ Johnson 2020, p. 93–96.
  9. ^ Johnson 2020, p. 96–102.
  10. ^ Johnson 2020, p. 102–106.
  11. ^ a b c d e Johnson 2020, p. 107–133.
  12. ^ a b c Johnson 2020, p. 201–222.
  13. ^ a b c d Taylor 1958.
  14. ^ a b c Taylor 1958, p. 48–50.
  15. ^ Downs 1999, p. 24.
  16. ^ a b Johnson 2020, p. xvi.
  17. ^ a b Johnson 2013, p. 172–175.
  18. ^ a b c Johnson 2020, p. 171–175.
  19. ^ a b Sutton 2020.
  20. ^ a b Taylor 1958, p. 50–51.

References

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