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Volcanic hazards for the fragile logistic on the islands of Vanuatu!
Research: Volcanic hazards for the fragile logistic on the islands of Vanuatu!
From year to year, erupting volcanoes cause threat and evacuations on some islands of Vanuatu, such as Ambrym, Ambae (Aoba) (in 2004/2005), Yasur, Gaua and Lopevi.
What potential hazard can cause the erupting volcanoes in general?
How does life goes on for the inhabitants?
Would help be needed for villagers and how much?
What logistic challenge has to be faced for aid work?
Since 1980, independent republic of Vanuatu is a group of 80 bigger Y-shaped islands about 1500 miles north of New Zealand and about the same distance east of Australia. Some complex plate tectonics (a kind of island arc mechanism) created this islands by uplift of ocean crust (first emerged from the sea 22 million years ago), but mostly by volcanism. Today we see a vaority of volcanism, such as lava lake activity at Ambrym, strombolian activity at Yasur and explosiv volcanism at the volcanoes Lopevi and Aoba (Ambea island). In 2004 and 2005 the volcano at Ambea and Ambrym caused evacuations to this islands because of very violent and ongoing eruptions.
Garet (Gaua Island) 14.27 S, 167.50 E, Alt. 797 m (Stratovolcano)
The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank of Mount Garat in 1962 ended a long period of dormancy. (GVNŠ)
Aoba (Ambae Island) 15.38 S, 167.83 E, Alt. 1496 m (Shieldvolcano)
Aoba, also known as Ambae, is a massive 2500 cu km basaltic shield volcano that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit of the Hawaiian-style shield volcano within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast. (GVNŠ)
Ambrym (Ambrym Island), 16.25 S, 168.12 E, Alt. 1334 m (Pyroclastic Shieldvolcano)
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. (GVNŠ)
Lopevi (Lopevi Island) 16.507 S, 168.346 E, Alt. 1413 m (Stratovolcano)
The small 7-km-wide conical island of Lopevi 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 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. (GVNŠ)
Yasur (Tanna Island), 19,52 S, 169,425 E, Alt. 361 m (Stratovolcano)
Yasur is one of the world's most active volcanoes and has been in continuous Strombolian and mild Vulcanian eruption for at least 800 years. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Yasur, located at the SE tip of Tanna Island, is a mostly unvegetated 361-m-high pyroclastic cone with a nearly circular, 400-m-wide summit crater. Yasur is largely contained within the small Yenkahe caldera and is the youngest of a group of Holocene volcanic centres constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions of Yasur has raised Port Resolution harbour more than 20 m during the past century.(GVNŠ)
Aid-management because of volcanic disasters!
Volcanic disasters can cause a lot of problems to the inhabitants of some islands of Vanuatu. Beside earthquakes, a hazard by Tsunamis, volcanic acid fall-out is one of the biggest threat by volcanic eruptions. Local habitants have to be evacuated whenever some of this threats or impacts are too severe.
But how can evacuation run efficiantly? Do habitants realy have to leave home and why? How could international aid and help do good for locals? All this is already discussed by organizations and authorities and some things are today solved and well organized. To improve aid-management, different datas and information, as well as diffenrent points of view can help. Thererfore we like to privide our reflection about local logistics on the following islands of Vanuatu:
The main logistic hubs of Vanuatu are the international airports of Efate (Port Vila), and on Espiritu Santo island (Luganville) with Pekoa (or Santo) airport. The so called calm Pasat or traders winds generate mostly southeastern wind directions as predictable circumstances. Dring the Cyclon season from December to March this storms can reach Vanuatu from the Coral See moving south-southeast.
VANUATU GEOHAZARD OBSERVATORY gives many answers and takes care nowadays:
Garet (Gaua island, 1.500 habitants)
GAUA CARVED UP BY INVESTORSOpen letter to the President and Provincial councillors, Torba
CLEARANCE WORK ON GAUA RAISES CONCERNE!
We the undersigned citizens and residents of Gaua would like to express our concern with respect to the work that is taking place on the slopes above Siriti village. The proposed cattle project currently raises three areas of concern: legal, environmental, as well as social.
Chairman Torba Tourism Council - Charles Bice;
East Gaua Council of Chiefs Chairman - Victor Wotias
(The Vanuatu Independent, www.independent.vu ; issue # 209, December 2007)
Open letter to the President and public of Vanuatu
ABOUT HAZARDS and PROTECTION of the NATURAL ENVIRONMENT of GAUA!
My name is Christoph Weber. I'm a germany volcanologist and work on active volcanoes since 10 years. I have visited Vanuatu a few times, but Gaua island only the first time in December 2007. I heard and read about the "cattle project" during this visit.
Christoph Weber (email@example.com)
(VHDL, January 2008)
ACTIVITY-NEWS from Oct. 2009!!!GAUA Banks Islands (SW Pacific) 14.27°S, 167.50°E; summit elev. 797 m According to news articles from 2 October, increased seismicity at Gaua was detected during the previous two weeks. Villagers living nearby reported ashfall and sulfur odors. Both villagers and a pilot flying past Gaua heard explosions. The Alert Level was raised to 1 (on a scale of 0-5).
Tuesday 6th December 2005 Ambae volcano has been raised to level 2 alert, indicating regular eruptions are occurring at the summit. Ambae volcano began erupting last week, after being dormant for about 120 years. 5000 people are being evacuated from dangerous areas in the east and west of the island.
Monday 5th December 2005 The eruption of Ambae Volcano in Vanuatu continues to cause problems for residents. Fears of further eruptions under lake Vui have required evacation of 5000 people from a 10 km danger zone to safer areas on the island. Volcanic activity is increasing, and ash emissions are occurring every 3 to 5 minutes. Emissions can be seen from neighbouring islands of Maewo and Pentecost. Measurements of gas emissions at the volcano indicate large amounts comparable to Yasur volcano in southern of Vanuatu. Acid rain may become a problem. Pentecost and Maewo remain the priority islands to settle the resident in the case of a mass evacuation.
Tuesday 6th December 2005 Ambae volcano in Vanuatu erupted on 27th November. Up to 5000 people in 15 villages have been affected. A new island was formed in one of the summit crater lakes (Vui). Further eruptions through the crater lake could prove dangerous. Food crops have been covered in ash.
Friday 25th February 2005 An earthquake on February 16th with an epicenter near Ambae volcano has caused concern among residents of the island. People living in the north to the western side of the island reported smelling sulphuric fumes after the earthquake. The Vanuatu Government is working on contingency plans to evacuate people if there are signs of an eruption. The last activity on Ambae Island was a phreatic eruption at Voui Crater Lake in 1995.
As of the 6th of December, the Global Volcanism Network (GVN) has reported that Mt. Ambae (a.k.a. Aoba) volcano erupted on 27 November in Ambae Island of Vanuatu. Ambae (Aoba) volcano has been raised to level 2 alert, indicating regular eruptions are occurring at the summit. Ambae volcano began erupting last week, after being dormant for about 120 years. 5000 people are being evacuated from dangerous areas in the east and west of the island. The volcano Ambae (Aoba) is a massive 2500 cu km basaltic shield volcano that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit of the Hawaiian-style shield volcano within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.
Sunday 6th March 2005 Volcanic activity continues at Ambrym Volcano. Remote sensing data indicate the proximity of magma to the surface. Ambrym is one of the world's most active volcanoes. It has been in almost continual eruption since Cook's visit in 1774. Destructive eruptions have affected local communities since March 2004, and residents are calling for food aid.
Wednesday 2nd March 2005 Residents of Ambrym Island in Vanuatu are calling for international assistance to help with the disaster caused by the ongoing volcanic eruptions. Ambrym is one of the world's most active volcanoes and has been in almost continuous eruption for the past 200 years. One year ago there was a change in eruptive activity which caused damage to food crops and created health problems for the residents. One year later, the volcano is still creating problems for the local communities, and the population is still calling for food aid to help prevent a famine on the island. Famine is the great forgotten killer of volcanic eruptions. During a survey of the volcano in November 2004, Volcanologist John Seach surveyed the damage to the island and made observations of the changes in volcanic activity. A new report received from the island 4 days ago by John Seach indicated that the situation is getting desperate for some residents who do not have enough food. So far only $1000 USD has been raised to help with food aid. Ambrym Volcano is closed to the public due to volcanic activity.
Friday 25th February 2005 West Ambrym has been declared a disaster area following eruptions and acid rain which has caused damage to food gardens. The community needs new crop plants and food aid to assist through the next 4 months of the declared disaster period. There needs to be a continued awareness programme on the volcanic hazard and risk, and measures to reduce the effects of the eruption. The government of Vanuatu is looking at a resettlement programme for the people displaced by the eruption. Reports from the island indicate that food crops have been destroyed by the ongoing eruptions and acid rainfall. Satellite images show continued hotspot activity at the volcano, indicating the proximity of magma to the surface. The volcano has been closed to the public until further notice due to volcanic activity.
Saturday 3rd December 2005 Eruptions continue at Lopevi volcano in Vanuatu. Satellite images show hotspots. There are no reports of ash emissions. Thursday 10th February 2005 Satellite images indicate possible eruptive activity at Lopevi Volcano in Vanuatu beginning at the end of January 2005 and continuing in February. Lopevi volcano is an uninhabited island in central Vanuatu, SW Pacific. Eruptive activity often goes unreported. The hotspot images indicates that magma is close to the surface, or there has been a small lava flow. Reports of eruptive activity in 2004. John Seach visited SE Ambrym volcano in November 2004 and received reports from residents about previously unreported eruptions of Lopevi in 2004.
During September 2004, five large booming noises were heard coming from Lopevi volcano by villagers in south Ambrym. Explosions were separated by 2 minutes. The next day there was ashfall on N and W Ambrym. The eruption was confirmed by satellite image on 28th September 2004. Hotspot activity was also noted at Lopevi on 13th May 2004 a satellite image. This correlates with eyewitness accounts of an eruption of Lopevi volcano obtained by John Seach during a field trip to the region.
As of the 1st of December, colleague Dr. John Seach, has reported that Yasur volcano in Vanuatu continues it impressive eruptive activity with many eruptions per hour. Yasur is one of the world's most active volcanoes and has been in continuous Strombolian and mild Vulcanian eruption for at least 800 years. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Yasur, located at the SE tip of Tanna Island, is a mostly unvegetated 361-m-high pyroclastic cone with a nearly circular, 400-m-wide summit crater. Yasur is largely contained within the small Yenkahe caldera and is the youngest of a group of Holocene volcanic centres constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. Active tectonism along the Yenkahe horst accompanying eruptions of Yasur has raised Port Resolution harbour more than 20 m during the past century.
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