[Vulkanen] The ring of fire #6: Waar diverse vulkanen puffen

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Op dinsdag 3 januari 2012 08:28 schreef marcel-o het volgende:
Was deze al bekend?

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Seven Indonesian volcanoes at level-3-alert status
JAKARTA: The Centre of Vulcanology and Geological Hazard Mitigation (PVMBG) on Thursday declared that seven out of 127 volcanoes in Indonesia are in danger status of level III (alert), according to China’s Xinhua news agency.

The volcanoes are namely Mount Papandayan in West Java province, Mount Lokon and Mount Karangetan of North Sulawesi province, Mount Kawah Ijen in East Java province, Mount Anak Krakatau in the border of Banten and Lampung provinces, Mount Gamalama at North Maluku province and Mount Lewotolo in East Nusa Tenggara province, respectively.

Out of the seven volcanoes, authorities are focusing on Mount Kawah Ijen, Mount Gamalama and Mount Lewotolo as their eruption impact is the biggest compared to others, said Head of the National Agency of Disaster Mitigation BNPB) Syamsul Muarif.

He said that the BNPB and regional agencies of disaster mitigation are enhancing preparation and planning to anticipate the impact of the volcanoes activities.

Explaining further, he said that Mount Kawah Ijen contains huge danger if it erupts as it threatens as many as 9,000 people living surround the volcano.

“The biggest threat of Mount Kawah Ijen is not hot cloud, flamed material launch or volcanic ash, but is within its volcanic lake containing 30 million metre cubic of water with deadly acid level,” he said, expressing disappointment that people refuse to evacuate despite several warnings.

While, increasing activities of the Mount Gamalama will expose and force, 638 people to take refuge. Last year, there people were killed by cold lava flood of the volcano following heavy rain on the top of the volcano.

Mount Lewotolo, with eruption type of explosive holds primary danger of volcanic bombs and hot cloud. However, Syamsul said that data shows that there has been no strong eruption that claims lives since 1660.

Although Mount Lokon in the city of Tomohon of North Sulawesi has erupted on Dec 27, last year, he said such incident still does not force people to take refuge.

“Mount Anak Krakatau that erupts almost every day with small intensity does not pose any danger to people as it locates in a strait connecting the islands of Java and Sumatra.

The volcano, he said is in a growth phase and there is a small possibility that it erupts like what happened in 1883, triggering strong tsunami and claimed thousands of lives. – Bernama

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Evacuaties na activiteit Lewotolo vulkaan in Indonesie
KUPANG, OOST NUSA TENGGARA - Honderden mensen in de buurt van de Lewotolo vulkaan op het eiland Lembata in de provincie Oost Nusa Tenggara zijn donderdag geëvacueerd nadat de vulkaan plotseling in activiteit toenam. Dit meldde persbureau Antara.

Zo'n 500 dorpelingen hebben hun huizen verlaten en zijn naar het stadje Lewoleba getrokken. Er zal bovendien snel een bijeenkomst gehouden worden op regionaal niveau om te kijken welke acties er verder nodig zijn. Dit meldde vice-districtshoofd Viktor Mado Watun van lembata.

Er komt op dit moment een dikke zwarte rookwolk uit de krater van de vulkaan. In het gebied is bovendien een sterke zwavellucht te ruiken. Ook produceert de vulkaan regelmatig een donderend geluid. Inwoners besloten dan ook en masse om hun dorpen te verlaten om veiliger gebieden op te zoeken.

Er is vanuit de overheid nog geen officieel evacuatie-plan opgesteld. Wel werd de alarm-status van de vulkaan in de voorbije dagen twee maal verhoogd, van status 1, normaal, naar status drie, op een schaal van vier.

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Chilian ONEMI raises status of Lascar Volcano
This first came up in the news yesterday, but I thought it deserved its own spot. Lascar, one of the more active volcanoes of northern Chile, was placed on heightened alert status by the ONEMI (Chilean Emergency Management) on advice from the SERNAGEOMIN (Chilean Geologic Survey). The latest report from Lascar says that over 300 small earthquakes (pdf) have occurred at the volcano in the last 26 hours, leading to an elevation of its status to Yellow – however, there have been no indications of increased fumarolic activity at the volcano. Lascar has the potential to produce a large eruptive column – the 1993 eruption sent ash as fall east as Buenos Aires – with pyroclastic flows that could reach nearby towns such as Talabre. The volcano has been through a number of cycles of significant explosive activity over its >43,000 year history. However, recent activity is mostly lava dome formation in the summit crater followed by crater collapse and vulcanian to plinian explosive eruptions such as the major eruption of April 1993. However, it also have the potential to produce small explosions that will only dust ash on the countryside surrounding the volcano as it has done at least 6 times in the last decade. ONEMI is preparing for possible evacuations for people near the volcano – mostly either miners in the area or tourists at San Pedro de Atacama. If anything does occur, there is a webcam pointed at Lascar to see the action.

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25 volcanoes in Indonesia show abnormal activity or are on alertstatus
Padang, West Sumatra. Twenty-five volcanoes in Indonesia are now showing abnormal activity or have been put on alert or watch status, presidential special aide Andi Arief said here on Saturday.

“According to official data, 25 volcanoes are now under alert or watch status and they must be given priority with regard to disaster mitigation planning at district or city levels,” he said at a workshop on journalists’ role in disaster management.

He said in West Sumatra there were two volcanoes that need to be closely watched, namely Mount Marapi and Mount Talang, as they are still under alert status.

Mount Marapi is located in Agam and Tanahdatar districts and rises 2891 meters above sea level, and Mount Talang (2597 meters above sea level) in Solok district was located around 40 kilometers from the provincial capital Padang.

Apart from the two volcanoes, the government and regional disaster management agencies were also giving priority attention to Mount Papandayan in West Java, Mount Karangetan and Lokon in North Sulawesi, Mount Ijen in East Java, Mount Gamalama in North Maluku, Mount Krakatau in Banten and Lampung and Mount Lewoloto in East Nusa Tenggara.

He said “it is not impossible that volcanoes that are now still normal could change to become abnormal due to earthquakes that have happened to trigger magma in the mountains to increase their activity, and therefore alertness and readiness of the people must continue to be maintained.”

Andi said earthquakes below five on the Richter Scale could trigger magma in the volcanoes to rise and so people must not only be alert over big but also small tremors.

The 4.4 magnitude earthquake like the one in Singkawang, West Kalimantan, is one of the examples, where people had never predicted before that it could happen there, he said.

“The small magnitude quake is now being studied by researchers with regard to minimizing the damage in case an eruption happens in the country as there are a lot of volcanoes in Indonesia,” he said.

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Santorini quake swarm continues- Greek media pick up news now
The highly unusual swarm of earthquakes SW of Santorini on the main fault zone that also defines the volcanic vents of the region continues with about 10 quakes larger than magnitude 2 during the past 24 hours. 2 of the quakes were magnitude 4 and 4.7, respectively.
Greek media start to pick up the story and become increasingly interested:

Today the wall of silence seems to be falling as a major Sunday newspaper has exclusive interviews with a number of Greek seismologists and geologists on the matter and some information is now public.

1. Inflation
From 1993 until 2010 there was deflation in the caldera of about 1cm/year, since the beginning of 2011 that has changed to inflation centered at a radius of 15 km on the north part of the caldera, rapid episodes of inflation have been recorded at intervals that coincide with bursts in seismic activity. Since August the intensity of the phenomenon warranted a rise to alert level 4 (red), where it has remained ever since.

2. Magma column
A displacement of 107 cubic meters has been located 1km north of the central island of Nea Kameni at a depth of 4 km, it is hypothesized that it is a magma intrusion, located right at the center of the most seismicity active part of the caldera.

3. CO2.
Co2 levels have jumped to 39 tonnes/day along with the emission of other gasses, a rising gas column has been observed outside the port of Thirassia in the caldera (the island on the west rim).

4. Water temperature.
The rise in sea water temperature in the caldera has been confirmed.

Most of the Greek scientists have brushed any concerns saying that conditions are normal and that has happened before, Euthimios Lekkas, geologist from Athens University, even said on TV that there is no danger even of a large earthquake in the vicinity of the island, the next day there were 3 earthquakes magnitude 5 and above, 50 km to the SW at the other end of the fault line.
Noticeable exception, foreign geologists have a very different opinion, Michelle Parks, a geologist from Oxford, mentioned that the evidence points to something important, there is volcanic activity and the volcano is now potentially active at depth.

Consensus is that the volcano has woken up in early 2011, but opinions differ mainly on the lines of nationality of the scientists.

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Semeru volcano alert status raised to level 3
A slight increase in activity of Semeru volcano's activity has been observed by the Indonesian Geological Survey in recent weeks and its alert level was raised to 3 (out of 4, "watch") on 3 February 2012, after it had been on level 2 since 16 July 2009.

Only small to moderate eruptions had been occurring over most of the past year. Between 29 December and 15 January, 8 explosions were counted which produced ash clouds up to 600 m high. One explosion threw incandescent bombs to a distance of 300 m from the Jonggring Seloko crater. During 15-29 January, only weak explosions were recorded and a small steam and ash plume rising 25-50 m was observed.

Between 30 and 31 January, 5 explosions were recorded. They produced incandescent fallout in up to 400 m distance. On 2 February at 07:47 local time, a stronger explosion produced incandescent bombs that reached 750 m distance and caused a small avalanche of blocks rolling down a distance of up to 2.5 km (note: no pyroclastic flows). The heightened activity triggered the raise in alert level the following day.

At its present status level of 3, PVMBG recommends to stay away at least 4 km from the summit on the SE side of the volcano and climbers are advised not to approach the Jonggring Seloko crater less than 1 km.
As of 6 February, no significant changes to its activity have been reported by our correspondent on location.

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Alertstatus Galunggung (Indonesia) raised
The alert status of Galunggung volcano in West Java, Indonesia, was raised today (Mon 13 Feb 2012) due to an increase of its water temperature and a change in color.

Discoloration of the crater lake had started to be noticed in September 2011, but the changes have increased recently. According to the local volcanologists monitoring the volcano, the whole lake is now of muddy khaki color. In addition to the color change which could be caused by an increase of lake fumarole activity, an steep sudden increase by 13°C of the lake water temperature was detected, based on measurements taken on and before 5 February when it was at normal 27°C, and on 8 Feb, when it was 40°C warm.
Most fish in the lake have died and occasionally dead birds are found at the shore.
No other signs of a possible volcanic awakening were detected at the moment. The ph level of the water is still at normal levels 7-8, and there is no sulfur smell. Also, no significant seismic activity has been detected.
Nevertheless, PVMBG has now placed the volcano at alert level 2 ("watch", on a scale of 1-4) and recommends to stay away at least 500 m from the lake shore.

The last eruptions of Galunggnug was a small phreatic explosion in 1984, and the major destructive eruption in 1982-83, which produced violent explosions with ash columns reaching 20 km height, pyroclastic flows and large lahars. The eruption destroyed an older lava lake, killed many people and displaced up to 35,000.
The eruption is infamous for the aircraft accident on 24 June 1982: a British Airways Boeing 747 with 262 people on board flew through the ash plume and had to make an emergency descent after the ash caused all 4 engines to fail; fortunately, the plane could land safely.

The present-day crater lake (Danau kawah Galunggung) has a diameter of 1000 m and is 11 m deep and contains a volume of about 8 million m3 of water.
In the middle of the lake, a small 250 x 165 m diameter scoria cone which was produced during the final staged of the 1982-83 eruption rises to 30 m elevation.
A main hazard of the volcano are phreatic and phreatomagmatic eruptions capable of draining the lake and producing mud flows.

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Nine small ash explosions at Fuego
Weak ash explosions continue at Fuego volcano. INSIVUMEH reported for 13 February that 9 eruptions were counted, producing plumes up to 500 m high and occasional rumbling noises. A steam plume is rising constantly about 100 m from the crater. The ash drifted 8 miles WSW.
The new lava flow on the southwest flank in the direction of the Taniluya ravine is still active and about 200 m long. Blocks that detach from its front form small block avalanches that reach the vegetation.

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Mt.Fuji Japan: Signs of unrest
Reports are appearing about unrest and signs of a possible awakening of Mt Fuji volcano in Japan.
According to a report which includes an unclear photo of the area, a row of new craters, the largest 50 m in diameter, has appeared on the eastern flank of the volcano at 2200 m elevation. Steam was observed erupting from these vents.

The observation joins other signs suggesting a gradual reawakening: A swarm of earthquakes including 4 of magnitude 5 have occurred northeast of Mt Fuji on and after 28 January. An earlier 6.4M quake occurred under the volcano on 15 March 2011. The report also mentions increased activity from a fumarole vent at 1500 m elevation and hot spring areas at the eastern flank observed since 2003.

These locations seem to be aligned geographically, and are probably connected. Dr. Masaaki Kimura of Ryukyu University is quoted to admit that there is an increased risk of and eruption on the eastern flank and that the status of the volcano should be closely monitored.

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New cracks in Canlaon Volcano crater Philipinnes
Three 50 m wide cracks have appeared on on the upper flank of Canlaon volcano (also spelled Kanlaon) near the crater after the M6.7 earthquake on Negros island in the Philippines on 6 Feb 2012.
According to PHILVOLCS, the Philippine volcano monitoring agency, the cracks were caused by the earthquake and are not likely a precursor for a new eruption, which would be the first since 2006, although Canalon is one of the country's most active volcanoes. A more detailed investigation is
planned and the mountain was for now closed for climbers.

Erik Klemetti on his more detailed post on Eruptions Blog mentions rightly that a major hazard from Canlaon volcano are landslides and mud flows, and that these are not necessarily related to an eruption, but can be triggered as well by heavy rain and gravitational instability caused by earthquake movements. In this context, the cracks should be examined and monitored carefully.

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New eruptions at Rincon de la Vieja Costa Rica
It has been almost exactly 14 years since the last eruptive period for Rincón de la Vieja in Costa Rica, but it looks like the volcano might be awakening from its break. Last Thursday (Feb. 22), the volcano experienced two small explosions in the early morning. Seismic records suggest the volcano also had small explosions on Feb. 19 and 20, according to the OVSICORI report for Feb. 25 (PDF). None of the explosions caused any damage to anything near the volcano and there are no reports of ash fall other than in the crater itself. These explosions are very similar in style to the September 2011 explosions that were like phreatic in nature — that is, not new magma but superheated water generated the explosions. Of course, it is likely that new magma intruding the volcano is the heat source for the water, but these explosions could precede a new magmatic eruption by months or years (or lead to nothing at all). The volcano sits within a national park in Costa Rica and after these explosions, the National Emergency Commission has declared the crater area off-limits to visitors.

The last major eruption from Rincón de la Vieja was in 1966, when it produced at VEI 3 event that generated pyroclastic flows. All the way back in circa 1820 B.C., the volcano produced the Río Blanco tephra from a larger VEI 4 eruption. The summit of the volcano hosts a small crater lake (see above), which could potentially add to the initial explosivity of any eruption as the water interacts with erupting magma. There are also abundant mudpots and springs within the national park as well, attesting to the persistent geothermal activity in the area. This geothermal activity is the reason why the Costa Rican government is looking to build a 200 MW geothermal energy plant in the National Park as well.

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Alertstatus of Ijen Volcano (Java) raised to 3 again
The official alert level for Ijen volcano in East Java, Indonesia, has been raised again to 3 ("alert") due to an increase in activity, our Indonesian correspondant Andi reports.
A new 10 m wide gas vent, which erupted buring gasses, was observed on 10 March at 17 m distance from the shore. Thick steaming, larger than usual, forming a thick white column of sulfur steam 200 m high was already noted since 3 March. Measurements of the lake water temperature at 5 m depth had also shown increased values of 42.70 deg C.

On 10 March, the lake surface was 2 meters higher than normal, although this could be attributed to heavy recent rain fall.

Another sign of increased activity is that many leaves of trees and other plants around the crater have died recently, suggesting higher than normal SO2 levels.

Seismic activity has been rising as well. Since 22 Feb, a near contiuous tremor signal has been being recorded. In the interval 22-31 Feb, there were 52 harmonic tremor periods lasting up to 20 minutes, as well as 17 2 low-frequency earthquakes, 38 mostly shallow volcanic quakes. This number increased to 306 tremor episodes lasting up to 25 minutes, 27 low frequency, and 125 mostly shallow volcanic earthquakes during the latest observation period between 1-10 March.

Ijen volcano in East Java, famous for its turquoise acid lake Kawah Ijen and the sulfur mine inside its crater, had been on higher alert starting 18 December 2011, but was lowered to alert 2 on 4 Feb this year, but is now again at the second highest level of 3, meaning that volcanologist think an eruption could be imminent. Access to the crater is currently closed.

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Smoke plume from Colombian volcano on Monday
MANIZALES, COLOMBIA (CBS) -- A rising smoke plume from a Colombian volcano put nearby cities and towns on alert as it continued to emit smoke, vapor and ash Monday.

The Nevado del Ruiz volcano, located in central Colombia about 130 kilometers (80 miles) west of Bogota, has been on yellow alert since October 2010 and began spewing ash and smoke last week.

The director of the Manizales seismic observatory, Gloria Cortes, said they are keeping a close eye on the volcano and monitoring seismic activity as they work with local officials to ensure the safety of nearby residents and tourists in the area.

"The local committee leaders, led by the area mayors, and given the current state of activity, have made a decision regarding the level of alert for the different areas and cities," Cortes said.

Authorities from cities in the volcano's proximity say they too are carefully watching the situation and have issued green and yellow alerts depending on how close they are to the volcano.

The mayor of Manizales, Jorge Eduardo Rojas, said his city is on green alert for now adding that could change if activity increases.

"Everyone needs to be ready for any situation. However, the city alert, which is at green, is still green and is not going to change though we are of course carefully watching for any changes on Nevado [del Ruiz]," Rojas, said.

Other cities closer to the crater are on an elevated yellow alert, though they say populated centers are not in imminent danger at the moment.

Thus far, the smoke plume has not caused any problems for air traffic.

The volcano's yellow alert means an eruption is possible though not definite. If it passes to orange it signifies an eruption is likely in weeks.