Posts Tagged ‘Mount Sinabung’

Mount Sinabung gets deadly as sightseers return

February 1, 2014

Mount Sinabung which has been erupting since September last year, has caused the first fatalities reported. It erupted again on Saturday ejecting rocks and ash and killing 14. The evacuation zone which extended upto 7km from the mountain has been relaxed to 5km, but the 14 people killed were all from the Suka Meriah village which is within 3km of the volcano. A group of sightseeing schoolchildren is reported to be among those killed. Another 3 people were severely injured when  apparently they had been visiting a family grave and their abandoned homes when the volcano spewed its ash.

On Friday the disaster management agency had allowed people living in villages more than 5km from the mountain to return home. Sixteen villages have been evacuated and residents are not supposed to visit for any reason.

The first eruption occurred at 10:30 a.m. and lasted for eight-and-a-half-minutes, spewing 2-kilometer ash and 4.5-km thick clouds to the south. The second eruption took place at 10:38 a.m. for just over four minutes, followed by another eruption at 11:27 a.m. for 84 seconds.

A villager run as Mount Sinabung erupt at Sigarang-Garang village in Karo district, Indonesia's North Sumatra province, February 1, 2014. REUTERS/Stringer

A villager run as Mount Sinabung erupt at Sigarang-Garang village in Karo district, Indonesia’s North Sumatra province, February 1, 2014.

Sources: Jakarta Post, BBC, Reuters

Related: 5 km radius around Mount Sinabung volcano evacuated as eruptions continue

The next VEI 5+ volcanic eruption is overdue

5 km radius around Mount Sinabung volcano evacuated as eruptions continue

January 13, 2014

Mount Sinabung keeps rumbling on – and more than just rumbling as eruptions with material ejected upto 5,000m and lava flows are observed. Around 25,000 people have been evacuated for 5km surrounding the volcano and the authorities are urging those within a 7km radius to leave.

JakartaGlobe:More than 25,000 people have fled their homes following a series of eruptions and lava flows from Mount Sinabung volcano, an official said Sunday. Mount Sinabung in North Sumatra sent hot rocks and ash up to 5,000 meters (16,000 feet) in the air “several times” on Saturday, National Disaster Mitigation Agency emergency response director Tri Budiarto told AFP.

“So far, 25,516 people have been evacuated. There’s nobody now within a five-kilometer [three-mile] radius of the crater. We are urging those living within seven kilometers southeast of the crater to move too,” he added. Hot lava, which has been spewing from the volcano for the past two weeks, has flowed into a river and filled up valleys with pyroclastic material, he said.

“There were small secondary explosions when lava flows came into contact with the water, but there are no casualties so far. We are urging people not to carry out any activity in the rivers,” he added.

Mount Sinabung is one of 129 active volcanoes in Indonesia that straddle major tectonic fault lines, known as the Pacific Ring of Fire. It had been quiet for around 400 years until it rumbled back to life in 2010, and again in September last year.

During the 19th century there were volcano eruptions having a Volcanic Explosivity Index (VEI) of 5 or greater on average every 11 years. During the 20th century the average was 7 years with the greatest interval between VEI5 eruptions being 23 years. The last VEI5 eruption was in 1991 and now – 22 years on – a VEI5 eruption is overdue.

Mount Sinabung started its rumblings back in September 2013 and it may be that the continuing small eruptions relieve sufficient pressure to prevent a VEI5+ eruption. But the odds that the next VEI5 eruption occurs in or around Indonesia is still quite high – and it could be that Sinabung is just bubbling up to be a major eruption. However the eruptions are being monitored so closely that any such imminent eruption will probably be detected early enough to get most people out of harms way.

Mount Sinabung Indonesia - Google Maps

Mount Sinabung Indonesia – Google Maps

The next VEI 5+ volcanic eruption is overdue

November 26, 2013

As Indonesia raised the warning level for the Mount Sinabung eruption it is worth noting that the last volcanic eruptions of  5 or greater on the Volcanic Explosivity Index (VEI) scale were the 1991 eruptions of Mount Pinatubo (VEI of 6) and Mount Hudson (VEI of 5).

The currently ongoing Mount Sinabung eruption (pictures here) gives cause for concern, as all Indonesian volcanoes do, but there is no certainty as to what intensity it may finally reach:

Jakarta Post: The volcanic ash spewed by Mount Sinabung in Karo regency, North Sumatra, disrupted a number of flights from Kuala Namu International Airport in Deli Serdang regency on Sunday.
In Bandung, the Center for Volcanology and Geological Hazard Mitigation (PVMBG) increased the volcano’s status to “awas” (beware), the highest level of the four-level alert system.

During the 19th century VEI eruptions of 5 or greater ocurred every 11 years on average with the Krakatoa eruption being the greatest at VEI 6 in 1883. Through the 20th century, an eruption of intensity 5 or greater came at intervals varying from 1 year upto 23 years with an average interval of just under 7 years. The Novarupta (1912) and Mount Pinatubo (1991) eruptions were the two classified at VEI6. 

  • 1902 Santa Maria
  • 1907 Kudach
  • 1912 Novarupta
  • 1913 Colima
  • 1918 Katla
  • 1932 Cerro Azul
  • 1933 Kharimkotan
  • 1956 Bezymianny
  • 1963 Mount Agung
  • 1980 Mount St. Helens
  • 1982 El Chichón
  • 1991 Mount Pinatubo
  • 1991 Mount Hudson

So far in this century the 2010 Eyjafjallajökull eruption in Iceland “only” reached a VEI intensity of 4. The 2012 Mt. Etna eruption was rated a 3+. 

The last VEI 5 level eruption was in 1991 and a major eruption of intensity 5 or greater is now  overdue. The interval of 22 years is almost as long as the longest interval between major eruptions in the 20th century. Of course even VEI 6 is still a great deal less than the VEI 8 of Toba or Yellowstone.

The VEI is an index taking both the volume of tephra ejected as well as the height to which it is ejected into account. While there is no evidence that the impact of volcanic eruptions is more than a temporary perturbation of the underlying climate cycle, these perturbations may well last a year or two. The effect on climate is usually that of cooling.

The most significant climate impacts from volcanic injections into the stratosphere come from the conversion of sulfur dioxide to sulfuric acid, which condenses rapidly in the stratosphere to form fine sulfate aerosols. The aerosols increase the reflection of radiation from the Sun back into space, cooling the Earth’s lower atmosphere or troposphere. Several eruptions during the past century have caused a decline in the average temperature at the Earth’s surface of up to half a degree (Fahrenheit scale) for periods of one to three years. The climactic eruption of Mount Pinatubo on June 15, 1991, was one of the largest eruptions of the twentieth century and injected a 20-million ton (metric scale) sulfur dioxide cloud into the stratosphere at an altitude of more than 20 miles. The Pinatubo cloud was the largest sulfur dioxide cloud ever observed in the stratosphere since the beginning of such observations by satellites in 1978. It caused what is believed to be the largest aerosol disturbance of the stratosphere in the twentieth century, though probably smaller than the disturbances from eruptions of Krakatau in 1883 and Tambora in 1815. 

But an eruption of VEI 5 or greater within the next year or two could well accelerate the underlying global cooling cycle that may be underway (and caused primarily by solar effects – direct and indirect).

The diagram below comes from a guest post by Dan Pangburn at The Hockey Schtick.

Global temperature anomaly and major volcanic eruptions

%d bloggers like this: