Archive for the ‘Volcanoes’ Category

Could Mount Agung eruption be the VEI 5+ volcano that is overdue?

October 16, 2017

We have not had a VEI 5+ volcanic eruption for 26 years since the Mount Pinatubo eruption in 1991. In 2015, I pointed out that the probability of a VEI 5+ volcano eruption within 5 years was over 95%. The probability of a VEI 5+ eruption in the next two years must now be approaching 99%.

(see also The next VEI 5+ volcanic eruption is overdue).

It has been 24 26 years since the last VEI 5+ (Mount Pinatubo, 1991, VEI 6) occurred and the probability that a VEI 5+ volcanic eruption will occur within the next 5 years is now over 95%. There are around 10 – 14 VEI 5+ eruptions every hundred years and for the the last 300 years the time between eruptions has been as short as 1 year and as long as 23 years. The current gap could be the longest recorded in three centuries. There are, on average, 2 eruptions of intensity 6 every hundred years and so the probability that an eruption of VEI 6 could occur within 5 years is about 50% (current gap 24 years, average gap 50 years). That a supervolcanic eruption of VEI 7 or greater could occur within the next 5 years is less than 1%.

Mount Agung’s volcanic activity is now reaching levels which suggests that an eruption is “imminent”.

Volcano Agung in Bali is showing worrisome signs of a major eruption, writes German climate blogger Schneefan here. The highest level of activity with multiple tremor episodes were just recorded. You can monitor Agung via live cam and live seismogram.

The 3000-mter tall Agung has been at the highest warning level 4 since September 21.

Schneefan writes that the lava rise has started and that “an eruption can be expected at any time“.

So far some 140,000 people have been evacuated from the area of hazard, which extends up to 12 km from the volcano. Schneefan writes:

Yesterday ground activity by far exceeded the previous high level. Quakes have become more frequent and stronger, which indicates a stronger magma flow (see green in the histogram). Since October 13 there has been for the first time a “nonharmonic trembling (tremor), which can be seen in red at the top of the last two bars of the histogram.”

The colors of the columns in the bar chart from bottom to top stand for perceptible earthquakes (blue) low eartnhquakes (green) surface quakes (orange . Just recently red appeared, signifying non harmonic tremors.  The seismogram below shows what are at times longer period quakes: meaning magma is violently flowing in the volcano. Source:

Since yesterday the seismogram for AGUNG has been showing powerful rumbling (red).

The seismogram of AGUNG shows powerful tremors (level RED). The seismogram is updated every 3 minutes: Source: Seismogramm

Because Agung is located near the equator, a major eruption with ash flying up into the stratosphere would have short-term climatic impacts that could last a few years.

Agung last erupted in 1963 with an explosivity index of VEI 5, sending a plume of ash some 25 km into the atmosphere before leading to a cooling of 0.5°C. The eruption of Pinatubo in the Philippines in 1991 led to a global cooling of 0.5°C.


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

Etna erupts for 12th time this year

September 1, 2011

Mt. Etna has been erupting regularly since January this year and erupted for the 12th time on Monday. Fantastic images but no great hazard apparently.

mount-etna-eruption-2011 video

Etna erupting for 12th time in 2011: image

Just coincidence? Burst of solar activity (Kp index) and 18 Indonesian volcanoes move to alert status

August 7, 2011

It may just be coincidence but I am inclined to believe that the sun does influence geo-magnetic activity on earth.

1.  The K7RA Solar Update


Solar activity markedly increased this week, with the sunspot number rising to 130 on Monday, August 1 — the highest since a reading of 131 on April 14, 2011. The average daily sunspot numbers more than doubled this week compared to last, rising nearly 54 points to 99.3. ……

NOAA’s Space Weather Prediction Center: “Three coronal mass ejections (CMEs) are currently en route to Earth, with the commencement of geomagnetic storming expected early to mid-day on August 5 with the arrival of the CMEs associated with the August 2-3 events. The third of the string, seemingly the fastest CME, may catch up with the first two in the next 12-18 hours, compressing the plasma and enhancing the embedded magnetic field. Storming levels are expected to attain G3 (strong) conditions. The current Solar Radiation Storm may experience a kick with the shocks and attain S2 (moderate) thresholds.

“Some level of geomagnetic disturbance is expected to continue through August 7 as the series of CMEs affect the Earth. Continued activity is likely from these regions as they continue to rotate off the visible solar disk over the next seven days. The Space Weather Prediction Center will continue to monitor this event as it unfolds.”

 Estimated 3-hour Planetary Kp-index


article image

2. The Jakarta Post:

Sun, 08/07/2011 1:05 PM

Eighteen Indonesian volcanoes are on “alert” status, two of which are at Alert Level 3, which is called “Siaga”, the Volcanology and Geology Disaster Mitigation Center says. Center head Surono said Sunday in Jakarta the erupting Mount Lokon in North Sulawesi and Mount Ibu in North Maluku were the two volcanoes at Siaga status. The center has adopted four levels of alert status: “Normal” (Level 1), “Waspada” (Level 2), “Siaga” (Level 3) and “Awas” (Level 4).

Surono said the conditions at Mt Lokon and Mt Ibu were currently considered most worrisome because they had been consistently erupting searing clouds affecting a radius of 2.5 kilometers. …… 

Surono added that 16 other volcanoes were at Level 2 alert status, “Waspada”, including Mt. Papandayan and Mt. Guntur in West Java. “Locals have reported several quakes,” he said. ….

Surono said that President Susilo Bambang Yudhoyono had summoned him on Saturday to report the volcanoes’ status and the center’s preparations to anticipate possible disasters.

H/T –


Solar effects will give increased volcanic and earthquake activity in the next 2 years

Kilauea Volcano eruptions may be entering new phase

March 7, 2011
Map showing relationship of Kilauea to other v...

Image via Wikipedia

Scientists on Sunday were closely monitoring heightened activity at Kilauea Volcano on the Big Island of Hawaii, after a fissure sent lava spewing 65 feet in the air.

Kilauea has been in constant eruption for 28 years. But geologist Janet Babb of the U.S. Geological Survey said this weekend’s activity indicates “new episodes in eruptions and further unknowns.”

On Saturday, one of the volcano’s crater floors, named Pu’u ‘O’o, collapsed 370 feet, the Geological Survey said. The event was accompanied by 150 small earthquakes, all confined to the volcanic area.

Separately, on the volcano’s eastern side, a 535 yard-long fissure in the ground opened, spewing lava 65 feet in the air, the Geological Survey said. Also, another crater called Napau began erupting.

File:30424305-045 large.JPG

An effusive eruption of basalt lava from Pu`u `O`o in 1984:image US Geological Survey,

Merapi: Residents flee Yogyakarta but flights resume to Jakarta

November 8, 2010


Mt. Merapi hazard map: image


Yogyakarta lies some 35 km from Mount Merapi but one of the “hazard” tongues from the volcano (see map above) leads directly to the city.

The Jakarta Globe reports:

Frightened residents in a bustling city of 400,000 at the foot of Indonesia’s rumbling volcano headed out of town Monday, cramming onto trains and buses and even rented vehicles to seek refuge with family and friends far away.

Mount Merapi, one of the world’s most active volcanoes, has erupted many times in the last century, killing more than 1,400. But Friday was the mountain’s deadliest day since 1930, with nearly 100 lives lost. The notoriously unpredictable mountain unleashed its most powerful eruption in a century Friday, sending hot clouds of gas, rocks and debris avalanching down its slopes at highway speeds, smothering entire villages and leaving a trail of charred corpses in its path.

All (international flights) were back in the air Monday and White House officials said Obama was still scheduled to touch down on Tuesday.

Merapi, meanwhile, showed few signs of tiring Monday, sending out thunderous claps as it shot clouds of gas and debris high into the air.
The Indonesian government has put Yogyakarta on high alert. Though there have been no orders to evacuate, many residents decided to go on their own.

Iceland on watch for new volcano eruption

November 1, 2010


Meltwater is flooding from the Grimsvotn glacial lake in Iceland and could signal the volcano underneath is about to erupt, a spokeswoman at the Icelandic Civil Protection Department told Reuters on Monday.

Water now pouring from Iceland’s biggest glacier, Vatnajokull, which sits on top of a number of volcanic hotspots, could be a sign of fresh geological activity, Civil Protection Department spokeswoman Gudrun Johannesdottir told Reuters.

In April, clouds of ash from an eruption under the Eyjafjallajokull glacier grounded flights across Europe for a week, causing billions of dollars in losses for airlines and other industries. Eyjafjallajokull is about 100 km southeast of Vatnajokull.

“We have to check if there will be an eruption,” Johannesdottir said. “Sometimes it initiates an eruption when a glacial outburst flood starts, but not every the time. So we are monitoring the situation closely.”

The latest eruption at Grimsvotn, in 2004, caused short-term disruptions to airline traffic into Iceland.


Smoke from a subglacial volcanic eruption rises above the Vatnajökull ice cap (file photo by Oddur Sigurdsson)



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