Misplaced Pages

#910089

55-594: Almost perfectly round in shape and about 30 km (19 miles) across, the island is a stratovolcano that reaches an elevation of 1,770 metres (5,807 ft) at Mount Veve . The island forms part of the southern boundary of the New Georgia Sound ; to the northwest the Vella Gulf separates it from Vella Lavella and Gizo , while to the southeast New Georgia lies across the Kula Gulf . West-southwest of Kolombangara

110-747: A 4-inch thick ash layer can weigh 120–200 pounds and can get twice as heavy when wet. Wet ash also poses a risk to electronics due to its conductive nature. Dense clouds of hot volcanic ash can be expelled due to the collapse of an eruptive column , or laterally due to the partial collapse of a volcanic edifice or lava dome during explosive eruptions . These clouds are known as pyroclastic surges and in addition to ash , they contain hot lava , pumice , rock , and volcanic gas . Pyroclastic surges flow at speeds over 50 mph and are at temperatures between 200 °C – 700 °C. These surges can cause major damage to property and people in their path. Lava flows from stratovolcanoes are generally not

165-535: A defence line through the Central Solomons. Naval battles nearby included the Battle of Kula Gulf and Battle of Kolombangara . The most famous and bloody battle was the mission to intercept the " Tokyo Express " supply convoy which resulted in the ramming and explosion of U.S. torpedo boat PT-109 , manned by John F. Kennedy and his crew. Australian coastwatcher , Sub Lieutenant Arthur Reginald Evans , who manned

220-474: A fast moving mudflow . Lahars are typically about 60% sediment and 40% water. Depending on the abundance of volcanic debris the lahar can be fluid or thick like concrete. Lahars have the strength and speed to flatten structures and cause great bodily harm, gaining speeds up to dozens of kilometers per hour. In the 1985 eruption of Nevado del Ruiz in Colombia , Pyroclastic surges melted snow and ice atop

275-515: A final intermediate composition . When the magma nears the top surface, it pools in a magma chamber within the crust below the stratovolcano. The processes that trigger the final eruption remain a question for further research. Possible mechanisms include: These internal triggers may be modified by external triggers such as sector collapse , earthquakes , or interactions with groundwater . Some of these triggers operate only under limited conditions. For example, sector collapse (where part of

330-738: A result of intraplate volcanism on oceanic islands far from plate boundaries. Examples are Teide in the Canary Islands , and Pico do Fogo in Cape Verde . Stratovolcanoes in the East African Rift include Ol Doinyo Lengai in Tanzania, and Longonot in Kenya. Subduction zone volcanoes form when hydrous minerals are pulled down into the mantle on the slab. These hydrous minerals, such as chlorite and serpentine , release their water into

385-443: A secret observation post at the top of the island's Mount Veve volcano, spotted the explosion. After decoding news that the explosion he had witnessed was probably from the lost PT-109 he dispatched Solomon Islanders Biuku Gasa and Eroni Kumana in a dugout canoe to look for possible survivors. Their efforts led to the subsequent discovery and rescue of John F. Kennedy and the surviving crew. After destroyers succeeded in sinking

440-461: A significant threat to humans or animals because the highly viscous lava moves slowly enough for everyone to evacuate. Most deaths attributed to lava are due to related causes such as explosions and asphyxiation from toxic gas . Lava flows can bury homes and farms in thick volcanic rock which greatly reduces property value. However, not all stratovolcanoes erupt viscous and sticky lava . Nyiragongo , near Lake Kivu in central Africa ,

495-486: A single Austronesian language. Pahu's cosmogonic account places the Kolombangara people's origin in the central caldera. Pre-colonial pacification saw them in small interior hamlets. European arrival and firearms led to hamlet modification for defence and shelter creation. Early European contact introduced disease, causing social disruption and depopulation. Simultaneously, subsistence changes saw men adopting migration as

550-552: A steep profile with a summit crater and explosive eruptions. Some have collapsed summit craters called calderas . The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity . The magma forming this lava is often felsic , having high to intermediate levels of silica (as in rhyolite , dacite , or andesite ), with lesser amounts of less viscous mafic magma . Extensive felsic lava flows are uncommon, but can travel as far as 8 km (5 mi). The term composite volcano

605-433: A way of life. Shifting cultivation on interior ridges vanished, and stone-faced pond field irrigation ceased by the late 1930s. Economic shifts from taro-dominated to yam-sweet potato agriculture by 1971 reflect agricultural technology regression or 'disintensification.' Bayliss-Smith et al. (2003) examined rainforest composition and human disturbance history in the western Solomon Islands, describing an agroforestry system in

SECTION 10

#1733084777911

660-647: Is Ghizo Island , upon which the Western provincial capital Gizo is located. The island is heavily forested, with few inhabitants. There are two notable settlements, Ringgi and Mongga, the former being the larger. The most significant industry on the island is logging, principally based at Poitete. Two sites associated with the island have been identified by BirdLife International as Important Bird Areas (IBAs) because they support populations of threatened or restricted range bird species. The Kolombangara Upland Forest IBA comprises 30,963 ha of forested land covering

715-527: Is a passive release of gas during periods of dormancy. As per the above examples, while eruptions like Mount Unzen have caused deaths and local damage, the impact of the June 1991 eruption of Mount Pinatubo was seen globally. The eruptive columns reached heights of 40 km and dumped 17 megatons of SO 2 into the lower stratosphere . The aerosols that formed from the sulfur dioxide (SO 2 ), carbon dioxide (CO 2 ), and other gases dispersed around

770-451: Is the most famous example of a hazardous stratovolcano eruption. It completely smothered the nearby ancient cities of Pompeii and Herculaneum with thick deposits of pyroclastic surges and pumice ranging from 6–7 meters deep. Pompeii had 10,000–20,000 inhabitants at the time of eruption. Mount Vesuvius is recognized as one of the most dangerous of the world's volcanoes, due to its capacity for powerful explosive eruptions coupled with

825-450: Is typically between 700 and 1,200 °C (1,300–2,200 °F). Volcanic bombs are masses of unconsolidated rock and lava that are ejected during an eruption. Volcanic bombs are classified as larger than 64mm (2.5 inches). Anything below 64mm is classified as a volcanic block . When erupted Bombs are still molten and partially cool and solidify on their descent. They can form ribbon or oval shapes that can also flatten on impact with

880-990: Is used because the strata are usually mixed and uneven instead of neat layers. They are among the most common types of volcanoes; more than 700 stratovolcanoes have erupted lava during the Holocene Epoch (the last 11,700 years), and many older, now extinct, stratovolcanoes erupted lava as far back as Archean times. Stratovolcanoes are typically found in subduction zones but they also occur in other geological settings. Two examples of stratovolcanoes famous for catastrophic eruptions are Krakatoa in Indonesia (which erupted in 1883 claiming 36,000 lives) and Mount Vesuvius in Italy (which erupted in 79 A.D killing an estimated 2,000 people). In modern times, Mount St. Helens (1980) in Washington State , US, and Mount Pinatubo (1991) in

935-403: Is very dangerous because its magma has an unusually low silica content , making it much less viscous than other stratovolcanoes. Low viscosity lava can generate massive lava fountains , while lava of thicker viscosity can solidify within the vent, creating a volcanic plug . Volcanic plugs can trap gas and create pressure in the magma chamber, resulting in violent eruptions. Lava

990-839: The British Solomon Islands protectorate . The island was occupied by the Empire of Japan in the early stages of the Pacific War . Led by Roger Green and Douglas Yen, the Southeast Solomon Islands Cultural History Programme (1970-1972) delved into archipelagic agricultural systems. In 1971, Yen and team explored Kolombangara, revealing promising irrigation remnants. Over 30 days, collaborating with locals unveiled Ndughore Valley's cultural landscape during early European contact. Limited 1971 knowledge hindered Kolombangara research dissemination. Despite this,

1045-572: The Philippines have erupted catastrophically, but with fewer deaths. Stratovolcanoes are common at subduction zones, forming chains and clusters along plate tectonic boundaries where an oceanic crust plate is drawn under a continental crust plate (continental arc volcanism, e.g. Cascade Range , Andes , Campania ) or another oceanic crust plate ( island arc volcanism, e.g. Japan , Philippines , Aleutian Islands ). Stratovolcanoes also occur in some other geological settings, for example as

1100-891: The magma is too viscous to allow easy escape of volcanic gases . As a consequence, the tremendous internal pressures of the trapped volcanic gases remain and intermingle in the pasty magma . Following the breaching of the vent and the opening of the crater, the magma degasses explosively. The magma and gases blast out with high speed and full force. Since 1600 CE , nearly 300,000 people have been killed by volcanic eruptions . Most deaths were caused by pyroclastic flows and lahars , deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes. Pyroclastic flows are swift, avalanche-like, ground-sweeping, incandescent mixtures of hot volcanic debris, fine ash , fragmented lava , and superheated gases that can travel at speeds over 150 km/h (90 mph). Around 30,000 people were killed by pyroclastic flows during

1155-443: The mantle which decreases its melting point by 60 to 100 °C. The release of water from hydrated minerals is termed " dewatering ", and occurs at specific pressures and temperatures for each mineral, as the plate descends to greater depths. This allows the mantle to partially melt and generate magma . This is called flux melting . The magma then rises through the crust , incorporating silica-rich crustal rock, leading to

SECTION 20

#1733084777911

1210-607: The 1902 eruption of Mount Pelée on the island of Martinique in the Caribbean . During March and April 1982, El Chichón in the State of Chiapas in southeastern Mexico , erupted 3 times, causing the worst volcanic disaster in that country's history and killied more than 2,000 people in pyroclastic flows . Two Decade Volcanoes that erupted in 1991 provide examples of stratovolcano hazards. On 15 June, Mount Pinatubo erupted and caused an ash cloud to shoot 40 km (25 mi) into

1265-916: The 1971 fieldwork on Kolombangara, renewed archaeological research in the New Georgia Group has established a regional cultural sequence for the Ndughore settlement landscape in the wider New Georgia Islands context. The 'Munda tradition,' defined by Walter and Sheppard based on Roviana lagoon research, spans the Bao period (1200 to 400 BC) and the Roviana period (400 BC to European contact). The latter witnessed new architectural forms, settlement patterns, and material culture, including coral-rubble skull shrines, fortification sites, and shell rings like hokata arm rings and bakiha rings of tridacna shell. This distinctive New Georgia cultural system, predating European contact, intensified in

1320-481: The 1982 eruption of Galunggung in Java , British Airways Flight 9 flew into the ash cloud, causing it to sustain temporary engine failure and structural damage. Although no crashes have happened due to ash, more than 60, mostly commercial aircraft , have been damaged. Some of these incidents resulted in emergency landings. Ashfalls are a threat to health when inhaled and are also a threat to property. A square yard of

1375-585: The 5,321 m (17,457 ft) high Andean volcano. The ensuing lahar killed 25,000 people and flooded the city of Armero and nearby settlements. As a volcano forms, several different gases mix with magma in the volcanic chamber. During an eruption the gases are then released into the atmosphere which can lead to toxic human exposure. The most abundant of these gases is H 2 O ( water ) followed by CO 2 ( carbon dioxide ), SO 2 ( sulfur dioxide ), H 2 S ( hydrogen sulfide ), and HF ( hydrogen fluoride ). If at concentrations of more than 3% in

1430-566: The Chinese state-owned China Forestry Group Corporation expressed interest in purchasing the hardwood forestry plantation that makes up much of the island, including a port and former airstrip that could be used as a base for Chinese military assets. Stratovolcano A stratovolcano , also known as a composite volcano , is a conical volcano built up by many alternating layers ( strata ) of hardened lava and tephra . Unlike shield volcanoes , stratovolcanoes are characterized by

1485-506: The Marovo Lagoon region of New Georgia Island around 1800. This system included irrigated taro pond fields, mixed bush-fallow swiddens producing dryland taro and yams, and fallow secondary forest enriched with Canarium nut trees. The same three components constituted the traditional agricultural regime on Kolombangara, based on discussions with Ghatere elders and observations in the Ndughore valley. The swidden component left little trace, but

1540-672: The New Georgia region, is documented in the Ndughore Valley sites, with surplus from irrigated taro fields likely supporting pig herds, contributing to ritualised feasting and status competition. Settlement patterns emphasised defence and fortification during increased inter-island raiding and headhunting. Residential sites like Patusugha, Heriana, and Vavalondu were on defensible hilltops, resembling small hamlets. Ivivu, modified in response to firearms, deviated from this pattern. Specialised ritual sites, such as Hena and Domana, were also part of

1595-500: The abandoned Japanese airstrip at Vila. The British government furnished 16 male natives to help with the project. With seeds acquired through the International Red Cross , many vegetables were sent back to the base hospital to supplement the dehydrated meals served the recuperating veterans. The main item was watermelons . Since 1978, the island has been part of the independent state of Solomon Islands . Beginning in 2019,

1650-816: The air, when breathed in CO 2 can cause dizziness and difficulty breathing. At more than 15% concentration CO 2 causes death. CO 2 can settle into depressions in the land, leading to deadly, odorless pockets of gas. SO 2 classified as a respiratory, skin, and eye irritant if come into contact with. It is known for its pungent egg smell and role in ozone depletion and has the potential to cause acid rain downwind of an eruption. H 2 S has an even stronger odor than SO 2 as well as being even more toxic. Exposure for less than an hour at concentrations of over 500 ppm causes death. HF and similar species can coat ash particles and once deposited can poison soil and water. Gases are also emitted during volcanic degassing, which

1705-741: The air. It produced large pyroclastic surges and lahar floods that caused a lot of damage to the surrounding area. Pinatubo , located in Central Luzon just 90 km (56 mi) west-northwest of Manila , had been dormant for six centuries before the 1991 eruption. This eruption was one of the 2nd largest in the 20th century. It produced a large volcanic ash cloud that affected global temperatures, lowering them in areas as much as .5 °C. The volcanic ash cloud consisted of 22 million tons of SO 2 which combined with water droplets to create sulfuric acid . In 1991 Japan's Unzen Volcano also erupted, after 200 years of inactivity. It's located on

Kolombangara - Misplaced Pages Continue

1760-454: The archaeological landscape of Kolombangara's Ndughore Valley. The economic base of the Ingoana people included swidden cultivation, arboriculture centred on canarium (nali nuts), and pond irrigation of taro. The Agegelai terraced system in the Ndughore Valley, with its complexity and well-designed canal network, constitutes a sophisticated irrigation system. Pig rearing, not extensively discussed in

1815-547: The central caldera and the high ridges of Mounts Veve and Rano, with four corridors down through lowland forest to the coast. The birds include yellow-legged pigeons , crested cuckoo-doves , Mayr's swiftlets , Roviana rails , Heinroth's shearwaters , Sanford's sea eagles , Meek's lorikeets , black-faced pittas , North Melanesian cuckooshrikes , white-winged fantails , Kolombangara monarchs , Kolombangara leaf warblers and Kolombangara white-eyes . The Kolombangara Marine IBA covers some 80,000 ha of marine waters around

1870-484: The early European contact period. During World War II the island and the waters around it were the scene of much fighting. The Imperial Japanese Army used an airstrip on some flat ground at Vila on the south shore of the island, and in May 1943 based several military units with over ten thousand troops garrisoned on the southeast side of the island under the command of Major General Minoru Sasaki , in an attempt to establish

1925-428: The exact nature of activities at Hena remained unclear, the presence of ritual elements was evident. Domana (site SN-4-13): Identified as a small ritual site, Domana consisted of a prominent upright volcanic slab flanked by fallen volcanic slabs. Referred to as a "devil's place" by informants, no additional information on its function or purpose was provided. Ivivu (site SN-4-5): The highest and most inland site, Ivivu,

1980-514: The expanded Western Solomons' archaeological record enriches understanding, contributing to New Georgia's early European contact insights. Logging since 1971 likely caused significant archaeological site destruction. Kolombangara, a circular extinct stratovolcano 15 km in diameter and 1770 m high at Mt. Veve, lies northwest of New Georgia Island. The Ndughore Valley, carved into the island's southwestern flank, stretches 6 km inland, with Ghatere village at its mouth. The Ndughore Valley choice for study

2035-540: The flank of a volcano collapses in a massive landslide) can only trigger the eruption of a very shallow magma chamber . Magma differentiation and thermal expansion also are ineffective as triggers for eruptions from deep magma chambers . In recorded history , explosive eruptions at subduction zone ( convergent-boundary ) volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens , Mount Etna and Mount Pinatubo , typically erupt with explosive force because

2090-478: The ground. Volcanic Bombs are associated with Strombolian and Vulcanian eruptions and basaltic lava . Ejection velocities ranging from 200 to 400 m/s have been recorded causing volcanic bombs to be destructive. Lahars (from a Javanese term for volcanic mudflows) are a mixture of volcanic debris and water. Lahars can result from heavy rainfall during or before the eruption or interaction with ice and snow. Meltwater mixes with volcanic debris causing

2145-458: The high population density of the surrounding Metropolitan Naples area (totaling about 3.6 million inhabitants). In addition to potentially affecting the climate, volcanic ash clouds from explosive eruptions pose a serious hazard to aviation . Volcanic ash clouds consist of ash which is made of silt or sand sized pieces of rock, mineral, volcanic glass . Ash grains are jagged, abrasive, and don't dissolve in water. For example, during

2200-500: The island of Kyushu about 40 km (25 mi) east of Nagasaki . Beginning in June, a newly formed lava dome repeatedly collapsed. This generated a pyroclastic flow that flowed down the mountain's slopes at speeds as high as 200 km/h (120 mph). The 1991 eruption of Mount Unzen was one of the worst volcanic disasters in Japan's history, once killing more than 15,000 people in 1792. The eruption of Mount Vesuvius in 79 AD

2255-503: The island, the site boundaries based on a seaward extension of 7 km from the coast, to encompass foraging and transit areas for the Heinroth's shearwaters that are believed to breed in the uplands of the island. The first recorded sighting of Kolombangara by western explorers was in 1568 by the Spanish explorer Álvaro de Mendaña de Neira . On March 15, 1893 Kolombangara was declared part of

Kolombangara - Misplaced Pages Continue

2310-439: The nineteenth century due to increased trade. Andrew Cheyne's 1844 trading post on Simbo Island linked iron axe heads to ritualised headhunting, especially with the introduction of muskets. Headhunting and the turtle shell trade intertwined in the late nineteenth century, contributing to ongoing feuds and retaliatory raids that depopulated many parts of the archipelago. Insights into this nineteenth-century cultural system come from

2365-496: The pre-GPS era. Two main clusters emerged: sites SN-4-2, -6, and -9 on the ridge above the Aghara and Agegelai irrigation complexes, and SN-4-12, -13, and -5 on a higher ridge further inland. Site SN-4-7: On the ridge to Patusugha, an earth oven and a flat stone with indentations for cracking nali (canarium) nuts were noted. Marked for further investigation as Site SN-4-7, no further exploration occurred. Patusugha (site SN-4-2): Spanning

2420-446: The ridge crest, featuring an ancestral shrine, house foundations, and anvil stones for processing nali nuts. Insights into ritual practices and daily activities were gleaned from this site. Hena (site SN-4-12): Characterized as a small site of special function on a flat-topped mound, Hena contained an ancestral shrine supported by a stone-faced terrace. Two rectangular platforms flanked the terrace with anthropomorphic facial motifs. While

2475-414: The same ridge as Patusugha, but at a higher elevation, Heriana had no fortification features. Cleared, mapped, and excavated, the site, described by informant Pahu, revealed four distinct features, including house foundations and earth ovens, shedding light on its structure and occupation period. Vavalondu (site SN-4-9): Further inland on the same ridge as Heriana, Vavalondu occupied a gently sloping area on

2530-420: The settlement pattern. Ancestral shrines in the Ndughore valley align with the broader pattern for New Georgia, conferring power in headhunting raids and participating in the regional shell exchange network. While the archaeology of Kolombangara Island remains little known, the study of Ndughore Valley sites sheds light on settlement patterns, economic production systems, and external exchange relationships during

2585-460: The size of Mount Pinatubo affected the weather for a few years; with warmer winters and cooler summers observed. A similar phenomenon occurred in the April 1815, the eruption of Mount Tambora on Sumbawa island in Indonesia . The Mount Tambora eruption is recognized as the most powerful eruption in recorded history. Its eruption cloud lowered global temperatures as much as 0.4 to 0.7 °C. In

2640-408: The supply ships three nights later and isolating the garrison of 12,400 there, US forces were able to "leapfrog" Kolombangara to land on Vella Lavella to the west. The Japanese evacuated Kolombangara between September 23 and October 4, 1943. In January 1944 a detachment of 1 officer and 6 enlisted men from the 350th Engineer General Service Regiment stationed at Munda, established a vegetable farm on

2695-645: The tree component, including Canarium nut trees, breadfruit, sago, and betel nut trees, was evident. Canarium or nali nut held cultural importance, featuring in feasts and preparation areas at archaeological sites. The most noticeable traces of the former three-tier agricultural system were linked to irrigated pond fields. Ghatere people guided researchers to formerly irrigated complexes in the Ndughore valley. Archaeological remains of irrigation are now described, with sites numbered using Roger Green's system. Notably: Daratovu (sites SN-4-10 and -11): Two small ovulologha irrigation systems were located on steep side channels of

2750-513: The upper Ndughore River at Daratovu. Both had stone terraces running across narrow, steep stream channels, forming 'barrage' terracing. Aghara (site SN-4-1): Aghara irrigation complex, recorded by A. M. Hocart in 1908, featured terraces dammed with stones. Mapped in 1971, it included 43 stone-faced pond fields organized into subsystems. Radiocarbon dating suggested the system's age range from AD 1504-1590 to AD 1616-modern. Agegelai (site SN-4-4): The most extensive irrigation system recorded, Agegelai,

2805-454: The western ridge overlooking the Ndughore valley, Patusugha, at an elevation of approximately 200 m, was where cultivators of the Aghara irrigation system once lived. Accessible by climbing a steep ridge from Aghara, the site covered about 70 m of ridge, with scattered house foundations, stone outbuildings, or earth terraces. Excavations provided insights into the site's historical and cultural aspects. Heriana (site SN-4-6): A small settlement on

SECTION 50

#1733084777911

2860-412: The world. The SO 2 in this cloud combined with water (both of volcanic and atmospheric origin) and formed sulfuric acid , blocking a portion of the sunlight from reaching the troposphere . This caused the global temperature to decrease by about 0.4 °C (0.72 °F) from 1992 to 1993. These aerosols caused the ozone layer to reach the lowest concentrations recorded at that time. An eruption

2915-624: Was a fortified hamlet modified for musket attacks. Situated on a steep ridge, Ivivu featured level terraces and platforms, defensive fosses, and a protective stone wall. An ancestral shrine at the site contained human remains, shell valuables, and pottery sherds, highlighting defensive modifications and potential historical disturbances. In summary, the survey of these northwestern Ndughore Valley sites revealed diverse features, including irrigation complexes, settlement sites, and ritual and defensive structures, providing valuable insights into their historical, cultural, and functional aspects. Decades after

2970-519: Was influenced by extensive remains of former Ghatere agricultural systems, known as Ingoana. Pahu, Ghatere's oldest resident and main informant, traced his genealogy four generations back to Valaka, the Ingoana's founding ancestor. Descendants of the Ndughore 'tribe,' once among seven tribes on Kolombangara, the Ingoana traditionally occupied land from north of Hunda to beyond Iriri. During the visit, Ingoana of Iriri and Ghatere were separated by Vavanga and Papele villages. Kolombangara inhabitants spoke Nduke,

3025-519: Was located upstream of Aghara on the north bank of the Ndughore River. Mapped in 1971, it had 91 individual pond fields, well-constructed stone retaining walls, and a hydrologically complex design utilizing water from the Ndughore River and a small tributary. Seven sites on the northwestern side of the Ndughore Valley were surveyed, with triangulated locations indicated in Figure 1 using compass bearings in

#910089