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ABSTRACT
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.
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.
Aoba (Ambae 10.000 habitants)
A professional hazard paper exist for Ambae island. So, our information are only additional. As we know from the physical morphology of the island, the central area of Ambae is the most dangerous on, because bigger explosive eruptions can cause lahars (mudflows) in a sudden. The lahars could be a result of rainfalls triggert by eruptions or because of water being blown out of the crater lakes of Aoba volcano by explosive activity. The outburst of lava on the outer flanks of the volcano are possible but usually do give anought time to evacuate dangered areas. Anyway, many villages could be effected by explosive volcanic hazards and this could last for quite a long time.
Local settlements are all around the volcano. Most of these villages do have 4-wheel-drive roads but during rain this roads may be out of use. The dustroads along the north coast (only) on Ambae is quite ok, but there are not much transport means for habitants and goods. This road might be cut off by eruptions. The evecuation runs usually by ship via Ndui Ndui (northern shore) or from the safer anchor at the notheast part of the island. Beside the Walaha airfield (the safe westend of the island), Laongana airfield is a hop off point for rescue in the east of Ambae.
Ambrym (8.500 habitants)
A very good volcanic hazard map (paper) by Michel Monzier and Claude Robin (ORSTOM 1996) exsist for Ambrym island. The shield volcano if Ambrym has a dense jungle vegetation around a central caldera. Whenever flank eruptions occure, enough time for evacuation should be no problem. The major threat is certainly acid fall-out (a mixture of ash and acid rain) which can last as long as an eruption goes. This can be up to month. If this acid fall-out poisens the water supply of local habitants, a big logistic problem occures quite in a sudden. If the acid fall-out destroys further on food plants and if it poisons (kills) farm animals such as pigs, chicken and cows, a desaster concering foodsupply for residents can be realy serious. The only way to help locals is with evacuations of the threatened parts of the island.
Food aid and other supply could be entered by the airfields of Craig Crove (westend of the island) and Ulei (southeast of the island). But for longer lasting help-programs, ships have to bring in supply with the safe harbors of Craig Crove and along the northern shore. A rough dust road winds along the southern shore. This road is good for evacuation, though trucks are short in this area. Locals told us that there are about 5 trucks to serve this road, which aren't enough to do efficient evacuation or help. In the north of the island we have the same situation concerning transport. If a bigger evacuation of the island should be necessary, ships from other part of the country are needed.
Lopevi (Epi Island 4.500 habitants; Paama 2.000 habitants)
The volcano Lopevi is about 14 km northeast of Epi island and only 5 km east of Paama island. The island is unhabitated since 1960 so we look at hazards only fot the nearby island. In case that a big explosiv eruption occures or that a part oft the steep strato volcano slides into the sea, Tsunamis can hit the islands of Paama, Epi and Ambrym very, very hard. The hole eastcoast of Paama will be effected. Ambrym will be hit at the south east tip of the island. We don't know how this will effect the habitians oft this two islands. But we know, that Epi will be severe effected on its hole eastcoast by any Tsunami. Some villages along the caost are close to the waterfront found on low altitude. The dust raod along the coast would be partly destroyed by a Tsunami so that help would be difficult to be carried out. The one lane road is in a quite good condition. In 2006 we have counted about 8 pick up trucks giving service on that particular raod and the hole island itself. This is not al lot any help can count on.
But not only Lopevi volcano can cause problems, as well the submarine volcano 2 km offshore of Epi (at Mt. Nitaia) and the submarine volcano Kuwae near Tefala island can especially trigger Tsunamis, but as well any other volcanic threat.
The logistic base (gate) for any aid on Epi island would be the airfields of Lamen Bay (at the safer northwestern end of the island) and Valesdir 27 km south of Lamen Bay.
Yasur (Tanna 21.000 habitants)
The volcano Yasur is monitored by local volcanologists. Implaced are three levels of volcanic hazard to give help how locals and visitiors should react on volcanic activity. The airfield of White Grass has a paved runway and is called "Tanna international airport". This makes it an ideal entry gate for any help. The road toward the east of the island and around the active volcano Yasur is a quite good, but partly a steep track. From the village Yaneumakel, anticlockwise around Yasur volcano as far as Port Resolution, the road goes along the foot of the 400 m high volcano Yasur. With big eruptions - security level 3 - this part of the road is threaten by the volcano. Some villagers towards the mountain of Tokusmera will be cut off by transport. Here we couned on some hundreds of habitants in 8/2006. The Port Resolution area will be cut off too of course.
In general, transport-logistics on Tanna island are plenty enough, but if bigger eruptions last long, this above mentioned problems and the cut off with supply for villagers will not be solved via the road around the volcano. So evacuation will be essential. A difficult story in terms of local politics and fincanial support.
VHDL - members of the 8/2006 workshop, leaded by Chris Weber:
Christian Falk
Franz Neubauer
Martin Rietze
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Manfred Meyer
Rainer Albiez
Gé Beijers
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Sandra Deckert
Hans-Juergen Knoblauch
Anita Wassener
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NEWS from 2005 (c)by John Seach:
Aoba:
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.
Ambrym:
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.
Lopevi:
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.
Yasur:
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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