Tag Archive | Pyroclastic Flows

Alert Level Raised To Maximum 4 At Sinabung Volcano In Sumatra, Indonesia

Red Alert Issued

The alert level of the volcano was again raised from “siaga” to “awas”, the highest on the Indonesian 1-4 scale. The reason is a currently elevated risk of possibly larger pyroclastic flows, that could be triggered by collapse of the increasing volume of the viscous lava lobe emplaced on the upper SE flank. 
 
The alert level of the volcano had been at 4 during late Nov 2013 until April 2014,- the first and so far most violent phase of pyroclastic flow generation after the lava had spilled over the summit crater and built a large lobe that reached the base of the cone.
The lava lobe on Sinabung’s upper SE flank on 3 June 2015 (Beidar Sinabung / facebook) 
Since then, for more than a year now, lava effusion has continued at mild, more or less constant rate. Tremor data suggest that the supply rate of magma to the volcano’s summit has been more or less constant during the past year.
 
This activity produced successive lava lobes on the upper flank, all on top and/or at the upper sides of the main flow emplaced during the first months of the eruption. Associated avalanches and pyroclastic flows had mostly been smaller in comparison, although a few larger ones occurred as well. 
 
 
Rock avalanche on the ENE flank (Mbah Lëwå / facebook)
 
However, the number of rock avalanches and pyroclastic flows has not been constant over time. It shows an amazing cyclic pattern at a rhythm of approx. 4-5 weeks for each. This corresponds to alternating phases of slow growth of a lobe, during which relatively few rockfalls occur, and a following period when the lobe is being destroyed by more frequent rockfalls / pyroclastic flows of various sizes.
 
Different to the previous episodes, the current lobe which appeared in late April has now become significantly bigger than its predecessors. Therefore, it could in turn also produce much larger pyroclastic flows if it collapses. Its volume has been estimated to be approx. 3 million cubic meters, about twice as the previous lobe that formed during late March-April.
 
The current lobe has even become large enough to overspill to the ENE side where a number of rock avalanches and smaller pyroclastic flows have started to occur, in an area that has not been touched for months.
 
Authorities started to evacuate more than 1,800 people from several villages (Jeraya, Mardinding, Sukanalu, Sigarang-fierce, Kutagugung, Lau Kawar) and the exclusion zone was increased to 7 km distance from the summit in the SE sector of the volcano.
Number of rockfalls / pyroclastic flows since 2015 (PVMBG)
Courtesy of volcanodiscovery.com

Eruption at Mt. Karangetang causes hundreds to flee in Indonesia

Volcano Alert

Hundreds of residents of Siau, Sitaro Islands regency, North Sulawesi, have fled to safer ground after Mount Karangetang erupted.
 
Mt. Karangetang erupted at 12:30 p.m. local time on Thursday, prompting residents in Bebali subdistrict, East Siau district, in Siau, Tagulandang and Biaro (Sitaro) Islands regency to seek refuge.
 
Thursday’s eruption discharged lava and sent volcanic ash and pyroclastic flows in the direction of the Batuawang River in East Siau district. The eruption caused panic among residents, who fled the area. People initially took shelter in the Bebali subdistrict office, but moved to the East Siau district administrative office in Ulu after volcanic activity increased.
 
Mt. Karangetang Observation Station head Yudia Tatipang said the volcano’s alert status remained the same despite the significant increase in volcanic activity.
 
“The alert status remains at level 3. Pyroclastic flows frequently occur,” said Yudia by phone.
 
He added that the volcano activity gave no signs of abating soon. “Residents are advised not to return home until further notice,” he said.
 
“This is the first time we have witnessed a massive eruption,” said Bebali district resident Junico Kasiuhe, 35.
 
According to Junico, Bebeli residents panicked and fled to safety.
 
“Residents are terrified of the pyroclastic flows as they are rapid and hundreds of lives could be lost in a matter of seconds. That’s why we immediately took the initiative to evacuate,” said Junico.
 
Kanang villager Harto Narasiang said the wind had carried volcanic ash to Karalung and Kanang villages in East Siau district.
 
“The blanket of ash can be 2 centimeters thick and has affected roads in both villages,” said Harto.
 
Sitaro Disaster Mitigation Center (BPBD) head Bob Wuaten said village administration offices had evacuated about 2,000 residents.
 
“The BPBD has evacuated about 465 residents to three shelters from both villages,” said Bob.
 
Besides the shelters, residents have also taken shelter at other residents’ homes. “We evacuated those living within a 200-meter radius from the lava flow. Currently, four homes have been buried by volcanic ash,” he said.
 
He added that the North Sulawesi provincial administration, BPBD and the local health office had provided relief aid. He urged residents to remain alert and to wear masks, especially those living along the Batuawang River.
 
East Siau district chief Wilman Panguliman said there was still volcanic activity as of Friday afternoon, although not as much as Thursday.
 
He added that aid supplies remained available, but evacuees needed mattresses and blankets.
 
Mt. Karangetang is also known as Api Siau, or Siau Fire. It is one of the most active volcanoes in Indonesia as it has erupted more than 40 times since 1675 and has had undocumented innumerable minor eruptions. An eruption in 1997 killed three people, while in August 2010 four people went missing during an evacuation effort.
 
The volcano is among a number of other volcanoes currently showing signs of activity, including mounts Soputan and Lokon in North Sulawesi, Mt. Gamalama in North Maluku, Mt. Slamet in Central Java and Mt. Sinabung in North Sumatra.
Courtesy of thejakartapost.com

Pyroclastic flows destroy village on southern flank at Sinabung volcano in Sumatra, Indonesia

Image: @endrolewa / twitter
A series of strong pyroclastic flows occurred yesterday 28 April 2015, reaching 3-4.5 km distance. The largest, at 18:20 local time touched and burnt the (evacuated) village of Guru Kinayan on the southern slope of the volcano.
 
The flows, at least 9 in total, were results of the partial collapse of the recently emplaced lava lobe on the steep upper flank. They occurred at 17:02, 17:20, 17:33, 17:44, 17:47, 17:50, 18:03, 18:20 (probably the largest one), and at 19:52 local time.
Courtesy of volcanodiscovery.com

**Aviation Red Alert**Large explosion, ash to 37,000 ft (11 km) altitude at Shiveluch volcano in Kamchatka, Russia

The volcano is in an intense phase of activity, characterized by strong explosions and partial collapses of the growing lava dome accompanied by tall ash plumes and pyroclastic flows. 
 
An explosion this morning produced an ash plume that rose to flight level 370, i.e. 37,000 ft (11 km) altitude, Tokyo VAAC reported. 
 
Aviation color code is red. Aircraft on the N-America – Japan routes are advised to avoid the area. 
 
On 28 Feb, a series of explosions and collapses produced tall plumes >10 km altitude and large pyroclastic flows up to approx. 4 km distance (image).
Courtesy of Volcano Discovery

Significant eruption and large pyroclastic flow at Sinabung volcano, Indonesia

Red Alert Issued

A significant eruption of Indonesian Mount Sinabung took place around 00:00 UTC on January 3, 2015, according to Darwin VAAC.
 
Although volcanic ash was not identified on satellite imagery, Aviation Color Code has been raised to Red.
 
A large pyroclastic flow followed today’s eruption.
View image on Twitter
Photo by Sinabung Volunteers
In their Volcanic Ash Advisory issued at 14:16 UTC today, Darwin VAAC said a high level of seismic activity is still being reported at the volcano.
The last time this volcano appeared in GVP’s weekly volcanic report was during the week of December 24 – 30, 2014: “Based on satellite images, webcam views, and weather models, the Darwin VAAC reported that an ash plume from Sinabung drifted almost 30 km SW on December 24.”
 
​ PVMBG reported that 53 pyroclastic flows at Sinabung occurred during December 8 – 16, 2014 and traveled as far as 4.5 km S and 1 km SE. Ash plumes rose as high as 5 km and drifted W and SW.
 
Since October a new lava dome had grown from the crater (on the W side of the lava tongue) and was 215 meters long. The main lava tongue was about 2 947 meters on December 15.
Courtesy of The Watchers

Strong eruption and major pyroclastic flow observed at Sinabung volcano, Indonesia

Volcano Alert
Darwin VAAC reported a high level eruption of Indonesian Sinabung volcano on December 14, 2014. Aviation Color Code was briefly set to Red and later downgraded to Orange as the eruption became less active.
 
At 02:32 UTC today (09:32 local time) volcanic ash cloud reached an altitude of approximately 6 km, and was extending 18 km to the NW.  Last high level erupting was observed at 03:40 UTC.
 
A large pyroclastic flow, approximately 4.5 km, was observed coming down the volcano yesterday.
 
Indonesian Mount Sinabung was sleeping for 400 years before awakening in August 2010. The latest series of eruptions started on September 15, 2013, and continued into 2014.
 
Two large pyroclastic flows on February 1, 2014, claimed lives of at least 14 people and severely injured 3 others.

Eruption Increases, Large Pyroclastic Flows At Sinabung Volcano, Sumatra
After a few days of deceiving calm, the eruption of the volcano intensified again today and produced the so-far largest pyroclastic flows, reaching probably more than 5-6 km in length, and associated ash plumes that rose to approx. 25,000 ft (8 km) altitude.
 
It seems that the previous dome which grew at the summit of Sinabung, collapsed a few days ago, leaving a large crater breached on the side where the earlier pyroclastic flows had gone down. The temporary absence of a lava dome in the past days led to the cessation of pyroclastic flows. Now, the new dome has again surpassed the boundary of the breach and sheds pyroclastic flows into the deep ravine below. (Thanks to B. Behncke for the comment) 
 
On the other hand, a strong increase in SO2 emissions and hybrid earthquakes indicate that a larger new batch of new magma has risen, which also explains the new more vigorous activity.

Uptake In Pyroclastic Flows At Tungurahua Volcano, Ecuador
The eruptive phase that had started on 6 Oct, after a quiet interval of 3 months, continues to increase. The volcano observatory reports ash columns rising up to 3 km above the crater and the first occurrence (so far) small pyroclastic flows.
In the early days of this phase, seismic activity was characterized by an increase in the number and energy of the events related to the mobilization of fluids into the volcano such as long-period events, tremor and explosions and emission signals of variable magnitude. Superficially, low intensity strombolian activity and ash emissions could be observed, resulting in ash fall in the areas of El Manzano, Bilbao, Chacauco , Choglontús , Mocha, Pillate and on the upper slopes of the volcano itself.
Seismicity peaked last Friday (11 Oct) when explosions and emissions generated emission columns of 500-2000 meters above the crater, with a low content of ash, causing further ash fall in several areas around the volcano.
Since past Monday (14 Oct), the number of explosions and seismic signals related to fluid movements has increased significantly again. Explosions were small to moderate and generated noises heard in several areas around the volcano. On Tuesday afternoon, two small pyroclastic flows formed during larger emissions, traveling a few hundred meters on the upper slope towards the Achupashal drainage.
Ash emission columns have been reaching 3 km above the crater and plumes drifted mainly towards the northwest.
SO2 emissions climbed from 90 tons per day and to 3000-4000 tons per day since 16 Oct, another indicator of fresh magma rising within the volcano.
Deformation has generally been low, but a month ago there had been inflation at the top of the cone.
Ash fall has occurred on all flanks of the volcano, and accumulated to more than 1 mm of ash in Baños de Agua Santa, Runtún and Penipe. A pause of activity occurred on 17 Oct, but resumed during the night between 17-18 Oct with more explosions that ejected large blocks and dense ash columns.
It is possible that this type of activity continues during the next days, and it is believed that the volcano is currently in a state of having an open conduit allowing the rapid rise of magma, resulting in the currently observed continuous mild to moderate explosive activity.
It is recommended to avoid the areas close to the volcano, in particular valleys that radiate from its flanks.