Semeru volcano (East Java, Indonesia): massive block and ash flow creates billowing ash plume
View of the pyroclastic flow at Semeru volcano this afternoon (image: Pasek Made / facebook)
The volcano had a significant eruptive phase this afternoon. Starting at around 17:24 local time, a pyroclastic flow was observed that traveled a distance of approx. 4500 m, according to Indonesia’s Civil Defense Agency BNPB.
The hot avalanche was likely caused by collapses of parts of the lava dome and/or upper parts of the lava flow on the steep southern slope of the volcano. Associated ash plumes rose to an altitude of 5500 m above sea level.
The volcanologists at the observatory registered a corresponding seismic signal with up to 22 mm amplitude that lasted for the considerable long period of 4287 seconds (approx. 1 hour 20 mins).
Telah terjadi Awan Panas Guguran (APG) Gunung Semeru dengan jarak luncur kurang lebih 4,5 KM pada Sabtu (16/1) pkl 17.24 WIB. #Semeru #InfoBencana #BNPBIndonesia pic.twitter.com/H6ndVbLU1w
— BNPB Indonesia (@BNPB_Indonesia) January 16, 2021
Another impressive video can be found on Pasek Made’s page on facebook, from where the attached image stems.
Volcanic activity worldwide 16 Jan 2021: Fuego volcano, Klyuchevskoy, Popocatépetl, Merapi, Semeru,…
Map of today’s active volcanoes
Klyuchevskoy (Kamchatka): (15 Jan) Volcanic Ash Advisory Center Tokyo (VAAC) issued the following report: ERUPTION AT 20210115/2125Z FL200 EXTD NE REPORTED OBS VA DTG:15/2120Z
Sakurajima (Kyushu, Japan): Volcanic Ash Advisory Center Tokyo (VAAC) issued the following report: EXPLODED AT 20210116/1619Z OVER FL060 EXTD SE OBS VA DTG:16/1610Z
Suwanose-jima (Ryukyu Islands): Volcanic Ash Advisory Center Tokyo (VAAC) issued the following report: VA IS NOT IDENTIFIABLE IN SATELLITE IMAGERY.
Sinabung (Sumatra, Indonesia): Volcanic Ash Advisory Center Darwin (VAAC) issued the following report: VA OBS TO FL130 AT 16/1721Z OBS VA DTG:16/1750Z
Merapi (Central Java, Indonesia): The activity of the volcano is on increasing trend. A first true pyroclastic flow descended this morning from the growing lava dome.
Early this morning at around 5 am local time, a larger rockfall disintegrated into a turbulent and highly mobile mixture of hot rocks, ash particles, and hot gasses, released from from the breaking lava particles,- a glowing avalanche that traveled approx. 1500 m downhill into the Kali Krasak valley. Ash plumes from rising fine material separating from the flow rose about 500 m.
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Semeru (East Java, Indonesia): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Darwin warned about a volcanic ash plume that rose up to estimated 18000 ft (5500 m) altitude or flight level 180 .
The full report is as follows: VA TO FL180 OBS FROM GND AT 16/1024Z OBS VA DTG:16/1132Z to 18000 ft (5500 m)
Popocatépetl (Central Mexico): (16 Jan) Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Washington warned about a volcanic ash plume that rose up to estimated 20000 ft (6100 m) altitude or flight level 200 .
The full report is as follows: ONGOING VA EMS. to 20000 ft (6100 m)
Fuego (Guatemala): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Washington warned about a volcanic ash plume that rose up to estimated 14500 ft (4400 m) altitude or flight level 145 .
The full report is as follows: NEW VA EMS. to 14500 ft (4400 m)
Sangay (Ecuador): Volcanic Ash Advisory Center Washington (VAAC) issued the following report: VA EMS HAS DISP
Reventador (Ecuador): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Washington warned about a volcanic ash plume that rose up to estimated 16000 ft (4900 m) altitude or flight level 160 .
The full report is as follows: ONGOING VA EMS. to 16000 ft (4900 m)
Sabancaya (Peru): Volcanic Ash Advisory Center Buenos Aires (VAAC) issued the following report: VA NOT IDENTIFIABLE
Satellite image of Klyuchevskoy volcano on 15 Jan 2021
Merapi volcano (Java, Indonesia): dangerous hot avalanches as lava dome continues to grow
Incandescent avalanches from Merapi’s lava dome this evening (image: VSI webcam)
The activity of the volcano is on increasing trend. A first true pyroclastic flow descended this morning from the growing lava dome.
Early this morning at around 5 am local time, a larger rockfall disintegrated into a turbulent and highly mobile mixture of hot rocks, ash particles, and hot gasses, released from from the breaking lava particles,- a glowing avalanche that traveled approx. 1500 m downhill into the Kali Krasak valley. Ash plumes from rising fine material separating from the flow rose about 500 m.
Such avalanches are known by volcanologists under the terms of nuée ardente, block-and-ash flow, pyroclastic flow or pyroclastic density current, and represent the deadliest volcanic hazard of volcanoes such as Merapi, which is a notorious producer of them during most of its eruptions.
While this morning’s flow was still a small one and still stopped relatively far from inhabited areas, the length of such pyroclastic flows can easily reach many kilometers, and larger ones should be expected to occur at any time now.
During the past few days, the new lava dome has been showing intense glow and near-constant incandescent rockfalls, suggesting that the rate of its growth has accelerated. Seismic activity has also shown a strong increase lately, which likely means that more magma is on its way up to the crater and into the dome.
As its mass increases, so does the risk that partial collapses from its sides generate more voluminous rockfalls and increasingly dangerous hot avalanches.
For now, and likely the foreseeable near future, they seem to be confined to emerging from the notch in the southwestern crater walls leading into the deep Krasak ravine. The Krasak valley and its banks are the highest risk zones at the moment.
Time-lapse video of this morning’s pyroclastic flow:
Histogram of seismic activity at Merapi (image: VSI)
