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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

volcanic activity

Publié le par Bernard Duyck
Publié dans : #volcanic activity
Anak Krakatau - Photograph by Toala Olivares 01.01.2019

Anak Krakatau - Photograph by Toala Olivares 01.01.2019

Surtseyan eruptions continue in Krakatau on 3 and 4 January.

The seismicity of January 3rd is characterized by 37 earthquakes of eruption, 42 earthquakes of emission, and a continuous tremor of amplitude between 1 and 15 mm, with a dominant to 7 mm.

For the 4th of January at 6am WIB, 13 eruptions are enumerated, with an amplitude of 15-22 mm and a duration between 40 and 110 sec. ; 5 emissions lasting between 35 and 65 sec. and with an amplitude of 14-21 mm. The tremor is recorded continuously with an amplitude of between 2 and 21 mm, with a dominant at 6 mm.

Among the heights of plumes emitted, there is that of the local 03.01 / 10h17 at 2,000 m, and that of 12:03 loc. at 1,500 m. altitude

The aviation code is orange; the level of activity remains at 3 / Siaga, with a prohibited area of ​​5 km

 

Sources: PVMBG, Magma Indonesia, BNPB and VAAC Darwin

Anak Krakatau - 03.01.2019 photo from an Indonesian patrol ship in the Strait of Sunda - Antara Foto / Sigid Kurniawan- via REUTERS

Anak Krakatau - 03.01.2019 photo from an Indonesian patrol ship in the Strait of Sunda - Antara Foto / Sigid Kurniawan- via REUTERS

Anak Krakatau - Volcanic Ash Advisory of 3 and 4 January - Doc. VAAC Darwin - one click to enlargeAnak Krakatau - Volcanic Ash Advisory of 3 and 4 January - Doc. VAAC Darwin - one click to enlarge

Anak Krakatau - Volcanic Ash Advisory of 3 and 4 January - Doc. VAAC Darwin - one click to enlarge

In Sheveluch, explosive-effusive activity continues on January 3 and 4, 2019.

KVERT reports plumes of gas, steam and ash at more than 5,500 meters asl, extending east on 03.01 and north-east on 04.01 extending 652 km.

Thermal anomalies reported by Mirova are considered high, ranging from 68 to 564 MW.

 

Sources: KVERT, VAAC Tokyo and Mirova

Sheveluch - thermal anomalies on 04.01.2019 / 1:40 - Doc. Mirova MODIS_Latest10NTI

Sheveluch - thermal anomalies on 04.01.2019 / 1:40 - Doc. Mirova MODIS_Latest10NTI

Sheveluch - Volcanic Ash Advisory for the 3rd and 4th of January - Doc. VAAC Tokyo - one click to enlargeSheveluch - Volcanic Ash Advisory for the 3rd and 4th of January - Doc. VAAC Tokyo - one click to enlarge

Sheveluch - Volcanic Ash Advisory for the 3rd and 4th of January - Doc. VAAC Tokyo - one click to enlarge

In Poas, Costa Rica, frequent steam eruptions are recorded, while the gray acid lake level is decreasing.
Seismicity is dominated by low frequency volcanic earthquakes and sporadic tremor, in relation to steam eruptions.

Source: Ovsicori

Poas - steam eruption of 03.01.2019 / 07:40 - webcam Ovsicori

Poas - steam eruption of 03.01.2019 / 07:40 - webcam Ovsicori

In Chile, the Villarica returns to its Strombolian explosions after a five-week break.

The lava fountains are projected 30 meters above the edges of the crater, and cause pyroclasts to fall eastward.

In 2019, a new camera should give us renewed images every second (instead of 10 seconds for the old one)

Source: Werner Keller / POVI

Villarica - webcam images from 03.01.2019 / at 4:47 and 5:23 - Doc. Povi

Villarica - webcam images from 03.01.2019 / at 4:47 and 5:23 - Doc. Povi

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Publié le par Bernard Duyck
Publié dans : #volcanic activity
Anak Krakatau - 02.01.2019 - photo Planet Labs Inc. via BBC

Anak Krakatau - 02.01.2019 - photo Planet Labs Inc. via BBC

After a brief lull, a strong explosive activity resumed at Anak Krakatau with the beginning of the year.

In a video made by the correspondent of Volcanodiscovery on 1 January 2019, cypressoid explosions are observed, with ejection of ashes, debris, water and steam several hundred meters away, as well as surges totally covering the island of Pajang, which now hides the view of the Krakatau.

Anak Krakatau - surtseyenne activity from 01.01.2019 - video of Doni Janskulo, Volcanodiscovery correspondent.

Anak Krakatau - Volcanic Ash Advisory for January 2nd and 3rd, 2019 - Doc.VAAC Darwin - One Click to EnlargeAnak Krakatau - Volcanic Ash Advisory for January 2nd and 3rd, 2019 - Doc.VAAC Darwin - One Click to Enlarge

Anak Krakatau - Volcanic Ash Advisory for January 2nd and 3rd, 2019 - Doc.VAAC Darwin - One Click to Enlarge

The VAAC Darwin reported on January 2, 2019 an ash plume that reached an altitude of 12,000 meters, and intermittent and regular emissions of ash up to 10,000 meters.

The eruption of Mount Anak Krakatau on 3 January 2019 at 12:03 WIB is characterized by a column of ash observed at ± 1,600 m above the summit (± 1,710 m above sea level), black , thick and leaning to the north and northeast. This eruption is recorded on a seismogram of maximum amplitude of 31 mm and a duration of ± 1 minute 10 seconds.
 
At present, G. Anak Krakatau is at Level III (Alert), with an orange VONA, and recommendations not to approach the crater within 5 km.
 
Sources: PVMBG, Magma Indonesia, Volcanodiscovery, VAAC Darwin

Lewotolo - archive image 07.2013 / Dan Quinn

Lewotolo - archive image 07.2013 / Dan Quinn

On 2 January, the PVMBG reported the level of Lewotolo at 2 / waspada due to an increase in volcanic earthquakes and fumarolic activity.
Since December 29, 2018, the seismic network has recorded 4 seismic swarms, a superficial earthquake and three deep volcanic earthquakes, indicating a possible magmatic intrusion
The Lewotolo is a stratovolcano located on an elongated peninsula, connected to the island of Lembata, in the sea of ​​Flores (small islands of Sunda); his last eruption was in January 2012.
 
Sources: PVMBG, Magma Indonesia

Lewotolo - seismicity on 02.01.2019 - Doc. Magma Indonesia

Lewotolo - seismicity on 02.01.2019 - Doc. Magma Indonesia

The last week of 2018 in Sabancaya / Peru was marked by a moderate eruptive activity, with an average of 23 explosions per day, and plumes of gas and ash reaching a maximum height of 3,300 meters above the crater, before reaching scatter 30 km to the east and west.
The seismicity is marked by LP earthquakes, related to fluid movements, and hybrid earthquakes, associated with the rise of the magma.
Two thermal anomalies were recorded, between 1 and 3 MW.

Source: I.G. Peru - OVI- Ingemmet

Sabancaya - activity from 24 to 30.12.2018 - Doc. I.G. Peru - OVI- Ingemmet

Sabancaya - activity from 24 to 30.12.2018 - Doc. I.G. Peru - OVI- Ingemmet

In Guatemala, prolonged and sporadic passive ash emissions, forming small plumes, are observed at Turrialba on 1 and 2 January 2019. Incandescence is visible at the western crater during the night.

Seismicity is characterized by small volcanic earthquakes and tremor.

Images from the Aura - IMO satellite indicate a substantial reduction in sulfur dioxide flux during the last half of 2018.

A few falls of ashes are reported in the Central Valley.

Poas - a low level lake and two active smokers - webcam Ovsicori 26.12.2018 / 11:38

Poas - a low level lake and two active smokers - webcam Ovsicori 26.12.2018 / 11:38

A small eruption occurred on January 2nd at 10am at Poas, accompanied by a column 50 meters above the crater; it lasted 2 minutes.

Ovsicori reports that these small eruptions of water vapor, magmatic gases and fine sediments are less frequent.

The crater lake, gray in color, has a low water level. Two smokers are active, one under water (mouth a), the other subaerial (mouth b, or sulfur). A general decrease in the emission of magmatic gases is noted in early January.

Source: Ovsicori

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Publié le par Bernard Duyck
Publié dans : #volcanic activity

A strong explosion occurred at the Nevados de Chillan complex on December 28th at 22:11 local / December 29 at 01:11 UTC; it was accompanied by an LP earthquake associated with fluid dynamics, with a hypocenter at one km depth.

Incandescence due to the emission of gases and pyroclastic materials at high temperature was observed, as well as external projections on the upper flank.

This episode is to link with the partial destruction of the dome, as part of the construction-destruction cycle started in December 2017.

On a Planetlabs video, it's possible to see a new and small crater on the eastern edge of Nicanor crater.

The technical alert remains at the Naranjo level.

Sources: Sernageomin & Felipe Aguilera

Nevados of Chillan - 28.12.2018 / 22:12 and 22:18 - Sernageomin photos

Nevados of Chillan - 28.12.2018 / 22:12 and 22:18 - Sernageomin photos

The KVERT momentarily changed the Sheveluch's aviation code from orange to red, following a continuation of the activity.

This December 30 at 00:45 UTC, an explosion of ashes was accompanied by two plumes. Satellite data show a first plume at 10-11 km asl drifting 35 km to the northeast, and a second plume at 6-7 km asl, drifting 244 km to the west-southwest of the volcano.

Sheveluch - ash explosion this 30.12.2018 / 0:45 UTC - photo Y.Demyanchuk

Sheveluch - ash explosion this 30.12.2018 / 0:45 UTC - photo Y.Demyanchuk

Sheveluch - Volcanic ash advisory of 30.12.2018 / 01h11 Z - Doc. VAAC Tokyo

Sheveluch - Volcanic ash advisory of 30.12.2018 / 01h11 Z - Doc. VAAC Tokyo

The aviation code returning orange at 6:14. ; the eruptive activity producing an ash plume at 5-6 km asl drifting 245 km to the southwest then to the west.

Steam and gas degassing continues.

Source: KVERT

Agung - 30.12.2018 -  eruption on vidéo at 4:12 am WITA and ashfall - montage Magma Indonesia

Agung - 30.12.2018 -  eruption on vidéo at 4:12 am WITA and ashfall - montage Magma Indonesia

An eruption marked the Gunung Agung, on the island of Bali, this December 30 at 04:09 WITA; she said 3 minutes 8 sec., with an amplitude of 22 mm on the seismogram.

The eruption is due to an "overpressure" due to the accumulation of volcanic gases. At the time of the eruption, an incandescence was observed at the top, but the height of the ash column was not observed due to the fog. According to satellite information, the volcanic ash is moving towards the southeast, reaching 5,500 m altitude. An orange aviation code has been established by VAAC Darwin.

Light ash rains were reported in the Karangasem regency, in the southeastern sector of Mount Agung, as in the city of Amlapura and in several villages including Seraya Barat, Seraya Tengah and Tenggalinggah.

Several volcanic earthquakes were recorded, including the earthquake on the northern slope of Mount Agung on December 28, 2018 of magnitude M2.7 at 2:49 WITA and M2.4 at 15:31 WITA. These earthquakes indicated the movement of magma towards the surface.

Based on the overall data analysis, the potential for a larger eruption is still relatively low. Eruptions that may occur at this time may take the form of ejection of incandescent rocks / lava, ash rains, or gusts of volcanic gas.

Until 30 December 2018 at noon WITA, it can be concluded that the activity status of Mount Agung is still at level III (pending) with a recommendation to estimate the danger zone in all areas within a radius. 4 km from the peak. The estimated danger zone is dynamic and continues to be evaluated.

The last eruption of Agung dates from July 27, 2018.

Sources: Magma Indonesia & VAAC Darwin

Etna - the NSEC & the eruptive crack - photos Joseph Nasi / Butterfly helicopters 28.12.2018 / 9h47-48 GMT
Etna - the NSEC & the eruptive crack - photos Joseph Nasi / Butterfly helicopters 28.12.2018 / 9h47-48 GMT

Etna - the NSEC & the eruptive crack - photos Joseph Nasi / Butterfly helicopters 28.12.2018 / 9h47-48 GMT

A mapping of the eruptive fissure, slag cones aligned above it and the lava field of Etna 24-27.12.2018 eruption was carried out by an overflight by the INGV and the coastguards of Catania.

The eruptive fissure consists of three segments: the northernmost is located just north of the new southeastern crater, at about 3,100 meters above sea level. This segment produced only a modest Strombolian activity of a few tens of minutes. The intermediate segment is located in the NNO-SSE direction and is approximately 750 meters long; it lies between the lower east flank of the new south-east crater, at a little over 3,100 meters above sea level, and the edge of the Valle del Bove, at about 2,875 meters. The lower segment of the crack enters Valle del Bove, crosses its west wall and stops at about 2,400 meters. It is about 1000 meters long, still in the NNO-SSE direction, but slightly eastward in relation to the segment described above.

The area covered by the erupting products does not exceed 1 square kilometer. According to a very preliminary estimate, the average thickness of these products varies between 3 and 6 meters. As a result, the total volume erupted is between 3 and 6 million cubic meters. On the evening of December 27, the most advanced lava front was very slow.

 

Source: Preliminary map of the Etna eruption from 24 to 27 December 2018 by Marco Neri

Etna - Preliminary map of the products of the eruption of 24 to 27 December 2018 - INGV Technolab via M.Neri

Etna - Preliminary map of the products of the eruption of 24 to 27 December 2018 - INGV Technolab via M.Neri

Etna - Result of interferometric processing in phase of SAR data - 2018.12.28 / 2018.12.22 - Doc. INGV

Etna - Result of interferometric processing in phase of SAR data - 2018.12.28 / 2018.12.22 - Doc. INGV

SAR (Synthetic Aperture Radar) images from the following two passages of the ESA Sentinel 1 satellite (European Space Agency), on 22 and 28.12.2018 were analyzed.

The geometry of the view of the sensor is decreasing ( East-South-East point of view of Etna, with an inclination of about 40 °).

The result of the interferometric treatment in the phase of SAR data included here (1 fringe = 28 mm of displacement along the line of sight) highlights a complex deformation field affecting the whole volcano.

The intrusion of 24 December in the upper Bove Valley, which caused a maximum deformation of about 16 cm to the west and 20 cm to the east;

The Fiandaca-Pennisi, Pernicanca and Ragalna faults were activated during the seismic swarm still recorded by the Etna networks.

Source and Details: Interferometric analysis of Sentinel-1 data Etna 22-28 / 12/18: preliminary report - link

Etna - towards a return to calm? - photo Gio Giusa 27.12.2018

Etna - towards a return to calm? - photo Gio Giusa 27.12.2018

 Etna - tremor at 29.12.2018 / 6h10 - INGV Catania

Etna - tremor at 29.12.2018 / 6h10 - INGV Catania

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Publié le par Bernard Duyck
Publié dans : #volcanic activity
Krakatau - surtseyan activity, characterized by cypressoid jets and ash plumes - images taken from a warship 28.12.2018 / Muhammad Adimaja via antara
Krakatau - surtseyan activity, characterized by cypressoid jets and ash plumes - images taken from a warship 28.12.2018 / Muhammad Adimaja via antara

Krakatau - surtseyan activity, characterized by cypressoid jets and ash plumes - images taken from a warship 28.12.2018 / Muhammad Adimaja via antara

According to recent visual observations, the top of the Anak Krakatau cone has disappeared. The PVMBG estimates that the highest point of the volcano has risen from 338 meters to 110 meters. From Pasauran's PGA post, the position of the top of Mount Anak Krakatau is currently lower than that of Sertung Island, which is the background. For the record, the island of Sertung is 182 meters high and 132 meters long.

The missing volume of Krakatau is about 150 to 180 million cubic meters ... which leaves it between 40 and 70 million cubic meters.

This change in morphology results from the combination of strong eruptive activity and slippage of a part of the volcanic body.

The current potential danger of the ongoing Gunung Anak Krakatau eruption is the more likely occurrence of Surtsey type eruptions, a phreatomagmatic type (direct contact between magma and seawater) producing a lot of ash.

The risk of another tsunami is considered low, unless reactivation of the fault structure in the Sunda Strait.

Krakatau's activity level remains at 3 / siaga, with a prohibited area of ​​5 km radius.

Anak Krakatau - images Sentinel-2 image bands 4,2,1 , respectively on 29.12.2018 (top) and 14.11.2018 (bottom), before and after the tsunami
Anak Krakatau - images Sentinel-2 image bands 4,2,1 , respectively on 29.12.2018 (top) and 14.11.2018 (bottom), before and after the tsunami

Anak Krakatau - images Sentinel-2 image bands 4,2,1 , respectively on 29.12.2018 (top) and 14.11.2018 (bottom), before and after the tsunami

Krakatau - extension of the ash cloud to the SW on 27.12.2018, respectively at 09.00 and 23.00 WIB - Doc. BMKG
Krakatau - extension of the ash cloud to the SW on 27.12.2018, respectively at 09.00 and 23.00 WIB - Doc. BMKG

Krakatau - extension of the ash cloud to the SW on 27.12.2018, respectively at 09.00 and 23.00 WIB - Doc. BMKG

The images of the Himawari RGB Citra Satellite show an ash distribution to a southwestern sector this December 27, at an altitude of up to 12 km asl. and a distance of 190 km.

On December 28, the surtseyan activity continues, accompanied by plumes at 2,500 meters.

Guide Andi Susanto Rosadi tried to make the tour of Krakatau on December 28, but had to give it up because of the bad weather generating lows of 1-5 meters.

Sources: PVMBG, BNPB, Communication Ministry of Energy and Mineral Resources Disaster Preparedness Team from 28.12.2018 / 17h - link and Antara news

Merapi - the summit and dome seen from the valley 27.12.2018 - photo Sukiman Lintas Merapi / Twitter

Merapi - the summit and dome seen from the valley 27.12.2018 - photo Sukiman Lintas Merapi / Twitter

 Merapi -  the summit dome degassing 27.12.2018 - photo Sukiman Lintas Merapi / Twitter

Merapi -  the summit dome degassing 27.12.2018 - photo Sukiman Lintas Merapi / Twitter

At Merapi / Java, the summit lava dome is observed on December 27th marked by a white and thick degassing at a max. 125 meters above the summit, from the observation post.

The deformation does not show any significant change.

The volume of the dome is estimated at 389,000 m³, with a growth rate of 2,300 m³ / day, larger than the previous week. It is considered as currently stable, and the level of activity remains at 2 / waspada, with a prohibited area of ​​3 km radius.

On December 28 at 8:25 pm, a debris flow traveled more than 300 meters towards Kali Gendol, and incandescence is visible northwest of the dome the same day at 22:04; Another flow is reported at 22:55 WIB with a course of 400 meters.... events described as currents in the process of dome growth.

Source: PVMBG

Merapi - hot spots of lava / debris flows on 28.12.2018, at 20:25, 22:04 and 22:55 - one click to enlarge - Doc.BPPTKGMerapi - hot spots of lava / debris flows on 28.12.2018, at 20:25, 22:04 and 22:55 - one click to enlarge - Doc.BPPTKG
Merapi - hot spots of lava / debris flows on 28.12.2018, at 20:25, 22:04 and 22:55 - one click to enlarge - Doc.BPPTKG

Merapi - hot spots of lava / debris flows on 28.12.2018, at 20:25, 22:04 and 22:55 - one click to enlarge - Doc.BPPTKG

The Colombian Geological Survey recorded on December 28 at 4:00. local seismic signal associated with fluid movements internal in Nevado del Ruiz.

The weather conditions did not allow to see if it was associated with an emission of gas or ashes; Ash falls are possible in a northwesterly direction towards Manizales, Villamaría, Chinchiná, Santa Rosa, and Pereira.

The level of activity remains at 3 / amarillo / changes in the behavior of volcanic activity.

Source: SGC

Nevado del Ruiz 28.12.2018 / 4h LT- sismo et spectrogram od the sismical signal  - SGC station sism OLB

Nevado del Ruiz 28.12.2018 / 4h LT- sismo et spectrogram od the sismical signal - SGC station sism OLB

Nevado del Ruiz - archive photo 17.09.2018 - SGC

Nevado del Ruiz - archive photo 17.09.2018 - SGC

In Kamchatka, the explosive-extrusive eruption of Sheveluch continues with this December 26 at 20h, an explosion of ashes to more than 7,000 meters asl. The ash plume slid north for 10 km.
The KVERT reports that weather conditions cause an increase in the activity of degassing the volcano, interspersed with ash emissions; the ash plume extends 40 km, drifting to the northwest on 27 December.

 

Sources: KVERT & VAAC Tokyo

 Sheveluch - lightning in the eruptive plume - photo 26.12.2018 / 20h22 IVS FEB RAS, KVERT

 Sheveluch - lightning in the eruptive plume - photo 26.12.2018 / 20h22 IVS FEB RAS, KVERT

In the Aleutian arc, a brief explosion was detected this December 29 at 3:17 UTC / December 28 at 18:17 AKST in Cleveland; a cloud of ash was spotted by a pilot at an altitude of 17,000 ft asl .

Typical explosions of this volcano, small clouds of ash dissipate within hours of their emission. The aviation code is orange.

Source: AVO

Cleveland - satellite image Worlview of 10.07.2018 / Dave Schneider / AVO - USGS

Cleveland - satellite image Worlview of 10.07.2018 / Dave Schneider / AVO - USGS

A powerful 4.8-magnitude earthquake occurred in the northern part of the Bárðarbunga caldera, one of the volcanoes overshadowed by the Vatnajökull icecap in Iceland, on 28 December at 01:16, followed by three earthquakes of significant magnitude. . The largest of them was from 3.7 to 1:38.

The seismic activity has found lower levels afterwards.

Bardarbunga - earthquakes at 28.12.2018 / 7.30am - IMO

The biggest earthquake that occurred in Bárðarbunga last week was M3.6. On the website of the Icelandic Meteorological Office / IMO, there is no sign of eruption in the region, but significant earthquakes have been detected regularly in Bárðarbunga since the 2014-2015 eruption in Holuhraun, and the collapse of the Bárðarbunga caldera.

Source: IMO

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Deferred by the news of Krakatau and Etna, return to the balance sheets of the year by the observatories:

 

In 2018, the Volcanic Monitoring Program developed several tools to improve the communication of the results of the continuous monitoring of volcanoes, including a scale of activity level, weekly and daily bulletins, and webcam views. seismic activity and gas geochemistry on the OVSICORI-UNA website: http://www.ovsicori.una.ac.cr/.

Volcanic monitoring is done from a network of different devices.

 

Costa Rica - scale of activity of volcanoes in 2018 - Doc.Ovsicori

Costa Rica - scale of activity of volcanoes in 2018 - Doc.Ovsicori

More specifically for active volcanoes in 2018:

The Turrialba is in activity level in 2018: 3 (erupting volcano) with an open system activity, generating frequent passive emissions of ash due to the slow but almost constant increase of a small magmatic volume.

On the 336 days of the year until December 20, the volcano emitted ashes for 194 days, more than 58% of the days of this year. At the beginning of the year and in August-September 2018, 2 inflation periods were detected that could be associated with a magmatic intrusion of 15 to 20 million cubic meters, at a depth of 10 to 15 km below the sealevel, located 3 km southeast of Irazú crater. These intrusions could be at the origin of the increase of eruptive activity on the volcano between February and March, as well as from May to October 2018.

Some explosions generated by these impulses were large enough to trigger a ballistic activity greater than 400 m around the crater.

Since the end of October, the magmatic activity has decreased but not the ash emissions. The hydrothermal system is considered to be formed again by generating explosive magma-water interactions and fragmentation of the magma in the column as the origin of ash emissions.

 Turrialba - summit on 30.11.2018 - photo jcarvaja17 / via Exploring Costa Rica

 Turrialba - summit on 30.11.2018 - photo jcarvaja17 / via Exploring Costa Rica

 Turrialba - 09.12.2018 - RSN webcam

 Turrialba - 09.12.2018 - RSN webcam

The Poas volcano is in activity level in 2018: 2 - 3 (active volcano - erupting)

It showed low activity, dominated by hydrothermal processes and degassing. Several periods of sustained activity have been recorded in the form of "borbollones".

In general, the flow of gas has significantly decreased compared to 2017 and the hydrothermal system has begun to reform, as evidenced by the recovery of the lake since January. This lake disappeared during the dry season (March-May) and reappeared later, generating variability in the monitored signals (seismicity, flow and gas ratios). The deformation recorded a slight deflation from June. No magmatic intrusion was detected.

The color of the lake changed from gray to green at the end of the year, which is generally associated with less intense convection activity in the lake despite the active maintenance of underwater fumaroles. And in mid-December 2018, eruptive activity increased, with hydrothermal eruptions with steam columns on December 19 and 20, and the near-disappearance of crater lake.

A change in the seismic model appeared on October 8 with many high amplitude LPs and short duration tremors, with no superficial manifestations.

Poas - modification of acid lake coloration 08.12.2018 - photo RSN

Poas - modification of acid lake coloration 08.12.2018 - photo RSN

Poas - plume of the phreatic eruption of 20.12.2018 / 8h19 - photo RSN

Poas - plume of the phreatic eruption of 20.12.2018 / 8h19 - photo RSN

The Rincon de la Vieja volcano has maintained an intense activity with frequent phreatic eruptions, but of a smaller amplitude than in 2017. A modification of the deformation model towards the extension was observed in October.

Rincon de la Vieja - phreatic eruption from 03.03.2018 / 16h12 - photo Ovsicori

Rincon de la Vieja - phreatic eruption from 03.03.2018 / 16h12 - photo Ovsicori

In 2018, volcanic activity associated with Irazú volcano remained very low. Some seismic swarms were recorded around May 20th. A permanent multi-gas station has been installed to detect the first signs of a possible magma intrusion. At present, no magmatic activity related to the Irazú volcano is detected.

 Irazu - photo 12.12.2018 / MSc. Elena Badilla Coto, profesor of Escuela Centroamericana de Geología UCR.

 Irazu - photo 12.12.2018 / MSc. Elena Badilla Coto, profesor of Escuela Centroamericana de Geología UCR.

The activity level of the Arenal in 2018: 0 (asleep) with potentially associated risks of earthquakes and landslides.

The deformation associated with the stabilization of the flanks of the volcanic building has decreased this year 2018. Some isolated LP earthquakes have been recorded that do not represent a new activity in the volcano. DOAS transects indicate that there is no SO2 emission. No magmatic activity was detected.

Source: Ovsicori - UNA & Red Sismologica Nacional

Arenal - photo tiempo CR 2018

Arenal - photo tiempo CR 2018

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Anak Krakatau - plume of 26.12.2018 - Photo by sukamdani_gunners543 Indonesian navy warship

Anak Krakatau - plume of 26.12.2018 - Photo by sukamdani_gunners543 Indonesian navy warship

Anak Krakatau - 26.12.2018 - we can see "the remains of the cone" between the islands - photo Du2nZizouEffenberg / Twitter

Anak Krakatau - 26.12.2018 - we can see "the remains of the cone" between the islands - photo Du2nZizouEffenberg / Twitter

After the eruptive sequence of December 22, with a continuous tremor with an excessive amplitude of 58 mm, the Anak Krakatau was marked at 21:03 WIB by a strong eruption.

Based on the satellite images, the PVMBG concludes that most of the Anak Krakatau has disappeared, causing a tsunami with deadly repercussions.

 

Since December 22, a sustained plume is emitted, and the seismicity is dominated by a continuous tremor, with a dominant at 25 mm (max 32 mm).

The volcanic ash is mostly distributed to the southwest, according to satellite radar images, this December 26th.

The satellites indicate heights between 15 and 18 km AGL at the point of emission (NOAA HYSPLIT model) and a displacement at more than 10 km altitude over a maximum of 130 km.

Ash falls are reported on Cilegon city and Serang this 26.12 to 17h WIB. (Liputan6)

Sulfur dioxide readings indicate a total mass of 0.022 Tg on December 26 at 19h UTC / 27.12 at 6hlocale (AIRS SO2)

Anak Krakatau - images of the plume on 26.12.2018, at 21.30 WIB and 27.12.2018 at 0:00 WIB - images Himawari RGB Citra - one click to enlargeAnak Krakatau - images of the plume on 26.12.2018, at 21.30 WIB and 27.12.2018 at 0:00 WIB - images Himawari RGB Citra - one click to enlarge

Anak Krakatau - images of the plume on 26.12.2018, at 21.30 WIB and 27.12.2018 at 0:00 WIB - images Himawari RGB Citra - one click to enlarge

Anak Krakatau - Analysis of radar images and ash trajectories on 24.12.2018 - sources: BPPT and NOAA HYSPLIT model
Anak Krakatau - Analysis of radar images and ash trajectories on 24.12.2018 - sources: BPPT and NOAA HYSPLIT model

Anak Krakatau - Analysis of radar images and ash trajectories on 24.12.2018 - sources: BPPT and NOAA HYSPLIT model

Anak Krakatau - Sulfur dioxide flow 27.12.2018 at 6am local (26.12 / 19h UT) - Doc AIRES - Total SO2 mass estimated at 0.022 Tg by S.Carn

Anak Krakatau - Sulfur dioxide flow 27.12.2018 at 6am local (26.12 / 19h UT) - Doc AIRES - Total SO2 mass estimated at 0.022 Tg by S.Carn

Given the parameters and terrible weather, the PVMBG decided to raise the Krakatau alert level to 3 / siaga, with a prohibited area of ​​5 km radius, December 27 at 6:00 WIB. A Volcano Observatory Notice for Aviation / VONA Red is issued from 27 December.
From yesterday to this morning, a visual contact makes it possible to observe a black and thick plume rising about 700 meters, with a wind blowing to the north and the east.

Status Gunungapi Diatas Normal

G. Sinabung

AWAS

02-06-2015

G. Anak Krakatau

Siaga

27-12-2018

G. Karangetang

Siaga

20-12-2018

G. Soputan

Siaga

03-10-2018

G. Agung

Siaga

10-02-2018

G. Merapi

Waspada

21-05-2018

Sources: PVMBG, Magma Indonesia, BNPB, and local press.
 

A link to the site and images of Øystein Lund Andersen, with his version of events on December 22 - link 

Etna - top degassing - photo J.Nasi / Butterfly Helicopters 26.12.2018 / 15h46 GMT

Etna - top degassing - photo J.Nasi / Butterfly Helicopters 26.12.2018 / 15h46 GMT

At Etna, the INGV specifies that the M4.8 earthquake of December 26 at 3:19 am is probably related to the activation of Fiandaca and Pennisi faults, and associated surface faults.

The earthquake would not be generated by magmatic movements, but constitutes a response of the volcano to a stress resulting from the intrusion and its transfer to the surrounding tectonic structures.

The seismic swarm has temporarily reached the number of 1,100 episodes, of which 60 exceed a magnitude of M2.5; the tremor after on increasing on 24,12, decreases slightly, still above the norm.

The general eruptive activity indicates a decrease, but one can not exclude a possible refeeding, on the basis of the geophysical signals, and an opening of new fractures to alitudes lower than 2,400 meters.

 

Source: INGV Catania

Etna - hot points and lava flows -  Sentinel 2 images 26.12.2018, respectively SWIR & Bands 12,11,4
Etna - hot points and lava flows -  Sentinel 2 images 26.12.2018, respectively SWIR & Bands 12,11,4

Etna - hot points and lava flows - Sentinel 2 images 26.12.2018, respectively SWIR & Bands 12,11,4

Etna tremor - diagram at 27.12.2018 / 0h40 - Doc. INGV Catania

Etna tremor - diagram at 27.12.2018 / 0h40 - Doc. INGV Catania

Etna - the NSEC - photo Gianni Pennisi 26.12.2018

Etna - the NSEC - photo Gianni Pennisi 26.12.2018

Note that the seismic activity of Stromboli was marked on December 24, between 8:00 and 8:20 local, by a series of signals repeating at regular intervals of 30 seconds for fifteen minutes.The frequency and shape of the wave are compatible with a fracking phenomenon likely to be located in the summit zone. (LGS / Laboratorio Geofisica sperimentale).

The alert level has therefore been raised from green to yellow, / unstable situation, and this although local observers do not notice more significantly larger explosions than usual.

 

Sources: LGS & INGV

Stromboli - seismogram of 24.12.2018 - see box in pink / 8h - 8h20 - Doc. LGS

Stromboli - seismogram of 24.12.2018 - see box in pink / 8h - 8h20 - Doc. LGS

In the Philippines, two phreatic eruptions are reported at Mayon this 27th of December at 8:17 and 8:28; they were accompanied by gray to greyish plumes rising respectively 600 and 200 meters above the summit, before drifting to the southwest.

During the previous 24 hours, a volcanic earthquake was recorded, as well as nighttime glow.

Inflation in the southeastern sector is still noticeable, and sulfur dioxide flux is measured at 1,943 tonnes / day on 25 November.

The alert level remains at 2.

Source: PHIVOLCS

Mayon - plume of the phreatic eruption this 27.12.2018 / at 8:19 - photo Kit / Twitter

Mayon - plume of the phreatic eruption this 27.12.2018 / at 8:19 - photo Kit / Twitter

A new lava flow / incandescent debris was observed at Merapi / Java on December 27 at 2:50 am HNE, about 300 meters long. The alert level remains unchanged.

Source: Merapi Observatory

Merapi - flow at 2:50 am on 27.12.2018 - Observatory Doc Merapi

Merapi - flow at 2:50 am on 27.12.2018 - Observatory Doc Merapi

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Publié le par Bernard Duyck
Publié dans : #volcanic activity

Sentinel 2 satellite images show that the activity of Karangetang / Api Siau , effusive since the end of November, continues on December 25 in the direction of the gorges located in the west-west.

The seismicity is directed since December 5-6 to avalanches of erosion of the lava  (guguran) until about December 22, before taking on a new aspect.

The Karangetang is in activity level 3 / Siaga, with a forbidden zone of 2.5 km to the northeast and southwest, increased to 3 km to the northwest. A Vona is orange, issued on 25.11.2018.

Sources: Magma Indonesia & Sentinel 2

Karangetang - 25.12.2018 - images Sentinel2 SWIR (above) and bands 12,11,8A (underneath) - one click to enlarge
Karangetang - 25.12.2018 - images Sentinel2 SWIR (above) and bands 12,11,8A (underneath) - one click to enlarge

Karangetang - 25.12.2018 - images Sentinel2 SWIR (above) and bands 12,11,8A (underneath) - one click to enlarge

Karangetang - table of seismicity at 25.12.2018 - Doc. Magma Indonesia

Karangetang - table of seismicity at 25.12.2018 - Doc. Magma Indonesia

At Anak Krakatau, still no new topographic data after the collapse that seems to be confirmed, due to significant cloud cover.

The lightning detection system provides information on a significant number of lightning flashes produced in the area over the last three days, the only sign of significant activity due to the interaction of magma with seawater.

Anak Krakatau - Tsunami trigger mechanism - 25.12.2018 - UNFPA Asia & Pacific

Anak Krakatau - Tsunami trigger mechanism - 25.12.2018 - UNFPA Asia & Pacific

Anak Krakatau -  analysis of image Sentinel-1 Citra radar at 23.12.2018

Anak Krakatau - analysis of image Sentinel-1 Citra radar at 23.12.2018

Anak Krakatau - synoptic table summarizing the mechanisms lead to the disaster, and counting the number of victims of the tsunami - via Antara

Anak Krakatau - synoptic table summarizing the mechanisms lead to the disaster, and counting the number of victims of the tsunami - via Antara

The seismicity table reveals only continuous tremor of amplitude 8-40mm, with a dominant at 20 mm.

The level of activity remains fixed at 2 / waspada, with a prohibited area of ​​2 km radius.

Sources: PVMBG, BNPB, Magma Indonesia

Probably one of the last photos of Anak Krakatau before its partial collapse in the ocean, and its change of appearance. - a collector by photo Øystein Lund Andersen 22.12.2018 / 18:59 local time

Probably one of the last photos of Anak Krakatau before its partial collapse in the ocean, and its change of appearance. - a collector by photo Øystein Lund Andersen 22.12.2018 / 18:59 local time

At Etna, details are provided by the INGV on the site of the last lava flows:

The eruptive fissure extended from the southeastern base of the new southeast crater to the west wall of the Valle del Bove, reaching a minimum altitude of about 2,400 meters above sea level. A second small eruptive fissure opened a little further north, at about 3,000 meters above sea level, between the new southeastern crater and the northeastern crater, and produced almost exclusively low Strombolian activity. for a few tens of minutes.

During its propagation, the open eruption fissure in the Valle del Bove fed lava flows that completely crossed the west wall of the valley, reaching its bottom and settling at 17:00 UTC on December 24, at varying altitudes of 1650 and 1800 meters.

In the early hours of December 25, the eruption is still in progress. A lava flow continues to flow into the Valle del Bove, fed by the eruptive fracture whose lower mouth is located at about 2400 m altitude, along the western wall of the valley.

Summit craters, particularly New Bocca craters and Northeast craters, produce continuous Strombolian activity that feeds a gaseous plume rich in volcanic ash.

The seismic swarm that accompanies the eruption continues; since yesterday morning, in about twenty-four hours, more than 900 seismic shocks have been recorded by the seismic network of the INGV Osservatorio Etneo.

During the night, from midnight, seven earthquakes were recorded, including one of M 3.3 at 01:09, with its epicenter 4 km north of Aci Sant'Antonio; an earthquake of M 4.8 at 3:18, with its epicenter 2 km north of Viagrande, was felt by the population and caused damage to Santa Venerina, Fleri and Lavinaio.

A section of the A18 Catania-Messina has been closed, where it appears that there has been a lowering of the road surface near Acireale.
At present, there are no casualties or serious injuries, only damage.

Sources: INGV Catania & local press

Etna - eruptive fissure at the base of the NSEC and flows towards the Valle del Bove - photo 24.12.2018 Emilio Messina

Etna - eruptive fissure at the base of the NSEC and flows towards the Valle del Bove - photo 24.12.2018 Emilio Messina

Etna - tremor at 26.12.2018 / 3:10 - Doc. INGV Catania

Etna - tremor at 26.12.2018 / 3:10 - Doc. INGV Catania

Etna - seismogram of the M4.8 earthquake of 26.12.2018 / 02:18 UTC - Doc. INGV

Etna - seismogram of the M4.8 earthquake of 26.12.2018 / 02:18 UTC - Doc. INGV

Etna - night earthquake damage in Fleri, Santa Venerina - photo Sabian Quattrocchi - one click to enlarge
Etna - night earthquake damage in Fleri, Santa Venerina - photo Sabian Quattrocchi - one click to enlarge

Etna - night earthquake damage in Fleri, Santa Venerina - photo Sabian Quattrocchi - one click to enlarge

In Ambrym / Vanuatu, the volcano is in minor eruption, level 3 with zones of danger unchanged.

This eruption is linked to a strong seismicity that could continue to affect existing fissures, especially in the southeastern part of the island.

As the analysis of the satellite data confirms a deformation of ground, other earthquakes are expected, perceptible or not by the population according to their magnitude.

Source: VMGD

Ambrym - earthquakes between 14 and 26 December 2018 serialized by dates / colors - Doc. GMVD

Ambrym - earthquakes between 14 and 26 December 2018 serialized by dates / colors - Doc. GMVD

Ambrym - 23.12.2018 deformation - deep source deflation and ERZ intrusion - Doc. VMGD GNS - JAXA

Ambrym - 23.12.2018 deformation - deep source deflation and ERZ intrusion - Doc. VMGD GNS - JAXA

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Publié le par Bernard Duyck
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Short news on this Christmas day ...

 

The new eruptive phase, started yesterday December 24 (see article), is after Boris Behncke the first flank eruption of Mount Etna for more than ten years on this site.

 Etna - 24.12.2018 - photo Guido La Rosa via Etna web

 Etna - 24.12.2018 - photo Guido La Rosa via Etna web

A new crack opened in the morning at about 3,000 meters above sea level at the base of the new south-east crater on the western flank of Valle del Bove, feeding a lava flow.

The entire summit area is deformed, and strombolian activity also concerns the northeast crater and the Bocca Nuova.



 

Etna - flank eruption started on 24.12.2018 - Lava flow in the Valle del Bove / Volcanodiscovery

The situation poses no danger for the inhabitants; only ashes and lapilli issued to a southeastern sector forced the partial closure of the Catania airport at 13:00 UTC, diverting incoming flights to other locations.

Falls of ashes and lapilli are reported on Zafferana, Santa Venerina and the south-east sector.

Etna - ash emissions cause diversion of flights to Catania - ash forecast for this 25.12.2018 / 00 to 18h by AshMALTA - one click to enlargeEtna - ash emissions cause diversion of flights to Catania - ash forecast for this 25.12.2018 / 00 to 18h by AshMALTA - one click to enlarge

Etna - ash emissions cause diversion of flights to Catania - ash forecast for this 25.12.2018 / 00 to 18h by AshMALTA - one click to enlarge

Etna - the fissural eruption this 24.12.2018 / 11:33 GMT - photo J.Nasi / Butterfly Helicopters

Etna - the fissural eruption this 24.12.2018 / 11:33 GMT - photo J.Nasi / Butterfly Helicopters

Etna - the lava flow in the Valle del Bove on 24.12.2018 / 17h50 - photo Basalto Caruso / Facebook

Etna - the lava flow in the Valle del Bove on 24.12.2018 / 17h50 - photo Basalto Caruso / Facebook

At the seismicity level, it is necessary to point a quake of magnitude 4.3 at 17:50, at a depth of 2 km. with its epicenter west of Zafferana Etna, marked by some damage. It was felt until Catania (INGV Terremoti).

Etna - earthquake of 24.12.2018 / 17:50 on the seismogram INGV ESVO_HHZ_IT.0004

Etna - earthquake of 24.12.2018 / 17:50 on the seismogram INGV ESVO_HHZ_IT.0004

Earthquake M4,3 recorded while recording this video on Mount Etna ! New eruption with lava flow - by Turi Caggegi

Thermal anomalies are high with a maximum of 2.294 MW on 24.12 / 21.15 (Mirova)

Incandescent mark three craters and the flank of Etna on a Sentinel 2 image of 24,12,2018 bands 12,11,8A.

 

Sources : INGV Catania and the different webcams and photographers mentioned, Sentinel 2

Etna - thermal anomalies at 25.12.2018 / 01h25 - Doc. Mirova_MODIS_Latest10NTI

Etna - thermal anomalies at 25.12.2018 / 01h25 - Doc. Mirova_MODIS_Latest10NTI

Etna - image Sentinel 2 bands 12,11,8A from 24.12.2018 - one click to enlarge; in this configuration, the snowy areas are in blue.

Etna - image Sentinel 2 bands 12,11,8A from 24.12.2018 - one click to enlarge; in this configuration, the snowy areas are in blue.

In Indonesia, after the tsunami, joint teams of the armed forces, the BPBD, the police, and many volunteers continue the search for survivors. The small islands between Krakatau and the coast of Sumatra are visited by boat.

The balance sheet is unfortunately heavier, with this December 24 at 17h WIB a provisional total of 420 dead, more than 1,500 wounded, and 128 missing.

Sources: Sutopo Purwo Negroho and international media.

Java - Joint teams of the Armed Forces, BPBD, Police, and many volunteers continue the search for survivors. - photo BNPB

Java - Joint teams of the Armed Forces, BPBD, Police, and many volunteers continue the search for survivors. - photo BNPB

At Merapi / Java, a lava flow of 300 meters long was observed towards Kali Gendol on 25 December at 0h12 WIB.

The alert level remains unchanged at 2.

Source: BPPTKG

 

Merapi - lava flow 25.12.2018 / 00:12 Wib - Webcam BPPTKG

Merapi - lava flow 25.12.2018 / 00:12 Wib - Webcam BPPTKG

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 Etna - 24.12.2018 - photo Maria Liotta - via EtNative & Meteo Etna

Etna - 24.12.2018 - photo Maria Liotta - via EtNative & Meteo Etna

From 8:50 am local time, an intense seismic swarm is observed on Etna. During the first three hours, more than 130 earthquakes occurred, the largest of which were of magnitude Ml = 4.0 (at 13:08), located in the area of ​​Piano Pernicana, on the northwestern side of the volcano, 2 km deep and 6 km west. from Zafferana Etnea) and Ml 3.9 (located in the area of ​​Monte Palestra on the NW side of the volcano).

The seismic activity was accompanied by a gradual increase in degassing from the summit crater area, initially with sporadic ash emissions from the Bocca Nuova and the Northeast crater, which ended around 12.00 pm to a dense and continuous plume of black ashes.

After about five minutes, intense Strombolian activity began at the south base of the new south-east crater, probably triggered by an eruptive fissure, and with the opening of several mouths towards Serra Giannicola (flank eruption).
At the same time, Strombolian activity is also increased at Bocca Nuova and Crater Nord-Est.

At 12:01 local time, the Etneo Observatory Office (OE-INGV) issued a Red VONA for the issuance of ashes to the aeronautical authorities.

Geodetic networks, GPS and inclinometers, show obvious deformations of the area of ​​the summit.

Source: INGV Catania

Etna - seismic activity of 24.12.2018 - Doc. INGV Catania
Etna - seismic activity of 24.12.2018 - Doc. INGV Catania

Etna - seismic activity of 24.12.2018 - Doc. INGV Catania

Etna - tremor on 24.12.2018 at 8:10 - INGV Catania

Etna - tremor on 24.12.2018 at 8:10 - INGV Catania

Etna - An eruption for Christmas  - photo J.Nasi / Butterfly Helicopters 24.12.201811h35 GMT

Etna - An eruption for Christmas - photo J.Nasi / Butterfly Helicopters 24.12.201811h35 GMT

Etna - the eruptive fissure on the NSEC flank -  photo J.Nasi / Butterfly helicopters le 24.12.2018 / 11h34 GMT

Etna - the eruptive fissure on the NSEC flank - photo J.Nasi / Butterfly helicopters le 24.12.2018 / 11h34 GMT

Etna - thermal webcam images INGV - RadioStudio7 and LAVE - one click to enlargeEtna - thermal webcam images INGV - RadioStudio7 and LAVE - one click to enlargeEtna - thermal webcam images INGV - RadioStudio7 and LAVE - one click to enlarge
Etna - thermal webcam images INGV - RadioStudio7 and LAVE - one click to enlarge

Etna - thermal webcam images INGV - RadioStudio7 and LAVE - one click to enlarge

Sources: INGV Catania and the different webcams and photographers mentioned

Sunda Strait's Tsunami - Official Flash # 2

Sunda Strait's Tsunami - Official Flash # 2

Last assessment and government communication on the Sunda Strait tsunami:

1. On December 22, 2018, the tsunami hit the coast of Sunda Strait and affected Pandeglang and Serang District in Banten Province, as well as Lampung Selatan, Tanggamus and Pesawaran, districts of Lampung Province. 

2. In five districts, Pandeglang District in Banten Province is the most affected region with 207 dead, 755 wounded, 7 missing and 11,453 displaced (1% out of a total of 1.2 million). An increase in the number of impacts is expected as the evaluation is still ongoing.

3. Indonesian President Joko Widodo traveled to Pandeglang on the morning of 24 December 2018. The priorities of the Indonesian government are coordination, research and development, evacuation, the provision of medical services, the management of internally displaced persons and the restoration of critical facilities.

4. The industrial zones of the Cilegon region have not been affected so far.

5. Local governments lead emergency response efforts in different affected areas.

Thousands of people participate in response operations, consisting of BNPB staff, Provincial and District Disaster Management Authority, Military Indonesia (TNI), Police, Indonesian Search and Rescue Agency (BASRNAS), Ministry of Defense Social Affairs, Ministry of Public Works, Ministry of Health, Ministry of Energy and Mineral resources, NGOs and volunteers. Heavy machinery is mobilized to support research and rescue operations in the affected areas.

6. On the basis of the AHA Center's communication with the BNPB, the tsunami's impact is still within the limits of the national capacities of the Indonesian government. There is no request for international assistance at the moment.

The BMKG issued an official statement on the cause of the tsunami at a press conference at the BMKG office in Jakarta on Monday (24/12). President Joko Widodo examined the site of the tsunami disaster on Monday in Pandeglang, the region with the highest number of casualties and damage.

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The latest assessment of the tsunami on December 24 at 19h WIB, still on the rise, mentions 281 dead, more than 1,000 wounded, 57 missing, and 11,687 displaced; the material damage concerns 611 houses, 69 hotels, 60 stalls and shops, 420 boats. (BNPB)

Tsunami report at 24.12.2018 / 22:00 WIB - Doc. BNPB

Tsunami report at 24.12.2018 / 22:00 WIB - Doc. BNPB

Return on the disaster, with the information of the moment:

A particularly violent episode took place on December 22 at 21:03 local, accompanied by an eruptive column more than 16,8 km, according to VAAC Darwin.

The two photos of Øystein Lund Andersen are accompanied by his comment: " I remember being surprised that activity had totally ceased, and Anak-krakatau wasnt even visible at all. No eruption sounds were heard. Then a few minutes passed, and the Tsunami arrived. "

Anak Krakatau - eruption on 22.12.2018 at 19:12 local - photo Øystein Lund Andersen

Anak Krakatau - eruption on 22.12.2018 at 19:12 local - photo Øystein Lund Andersen

Anak Krakatau eruptive site 22.12.2018 at 21:26 WIB - photo Øystein Lund Andersen

Anak Krakatau eruptive site 22.12.2018 at 21:26 WIB - photo Øystein Lund Andersen

The explosion / blast must have dislocated much of the island, causing an aerian collapse (and / or submarine) in the south and southwest areas, which caused the tsunami. The latter could, according to Simon Carn, have been reflected / diffracted by the remains of the caldera, resulting in complex dispersion patterns.

Note that a simulation carried out in 2012 (reference sources) indicated the coastal areas possibly affected by a tsunami following a collapse of the southern flank of Anak Krakatau ... they were actually affected by the tsunami of 22.12. 2018.

Max. waves in the simulation of Giachetti & al. The main cities or important infrastructures possibly impacted around the Strait of La Sonde are indicated by red diamonds BL: Bandar Lampung; K: Kalianda - on Sumatra - M: Merak; A: Anyer; C: Carita; L: Labuhan; P: Panimbang - on Java.

In his conclusions, "the numerical simulation shows that a partial destabilization (0.28 km3) of Anak Krakatau to the southwest could be dangerous at the local level (tourism and fishing activities around the volcano) or even at the regional scale (Sumatran and Java coasts). "

"Due to the large population, the concentration of road and industrial infrastructure along parts of the exposed java and Sumatra coasts, and the low elevation of most of these lands, the tsunami could pose a significant risk. "

"However, as the tsunami travel time is several tens of minutes between the Krakatau archipelago and the main cities along these coasts, a rapid detection of the collapse of the Volcano Observatory, coupled with a system effective warning on the coast, could prevent this hypothetical event from being fatal. "

 

A premonitory tweet of March 2018 by Simon Carn warned again of the potential danger in connection with the constant erection of Anak Krakatau on the edge of the caldera formed by the eruption of 1883.

Anak Krakatau - 23.12.2018 - black cypressoid jets and white plume of steam - Kumparan photos - by Dicky Adam Sidiq uploaded to 16h WIB
Anak Krakatau - 23.12.2018 - black cypressoid jets and white plume of steam - Kumparan photos - by Dicky Adam Sidiq uploaded to 16h WIB

Anak Krakatau - 23.12.2018 - black cypressoid jets and white plume of steam - Kumparan photos - by Dicky Adam Sidiq uploaded to 16h WIB

The eruption of Anak Krakatau continued on 23 December:

Function of the aerial images available (Kumparan - by Dicky Adam Sidiq put on line around 16h WIB), showing black cypressoïdes jets and whites plume of steam, base surges at the base, one can qualify the current phase of the surtseyan type  (see phase of the 1963 eruption that led to the emergence of the island of Surtsey) during which the magma comes out under water, shallow, with significant fragmentation.

We went from a magmatic eruption to a pheatomagmatic eruption.

Anak Krakatau - surtseyan activity from 23.12.2018 - note the collapse scar on the left of the blast on the picture above - and the collapse of the plume generating the blast on the picture below - Grand Carava Susi Air photos via BNPB
Anak Krakatau - surtseyan activity from 23.12.2018 - note the collapse scar on the left of the blast on the picture above - and the collapse of the plume generating the blast on the picture below - Grand Carava Susi Air photos via BNPB

Anak Krakatau - surtseyan activity from 23.12.2018 - note the collapse scar on the left of the blast on the picture above - and the collapse of the plume generating the blast on the picture below - Grand Carava Susi Air photos via BNPB

Vidéo Kumparan

Kompas TV video

A lot of lightning was detected by the WWLLN Lightning strike detection this December 23 : 10,856.

More than 10,000 lightning strikes recorded during the day of 23.12.2018 - Doc. WWLLN Lightning strike detection

More than 10,000 lightning strikes recorded during the day of 23.12.2018 - Doc. WWLLN Lightning strike detection

Summary of the day of December 23 in 2 images: desolation, and power released by the current eruption.

The wave submerged the entire coastline, here in Anyer on 23.12.2018. Doc. EPA-EFE / ADI WEDA

The wave submerged the entire coastline, here in Anyer on 23.12.2018. Doc. EPA-EFE / ADI WEDA

The Kompas front page of this 24.12.2018

The Kompas front page of this 24.12.2018

Sources:

- Kumparan news - https://kumparan.com/@kumparannews/foto-udara-situasi-terkini-gunung-anak-krakatau-1545561798885566899

- Tsunami hazard related to a flank collapse of Anak Krakatau Volcano, Sunda Strait, Indonesia - T. Giachetti, R. Paris, K. Kelfoun and B. Ontowirjo

Geological Society, London, Special Publications, 361, 79-90, 3 January 2012, https://doi.org/10.1144/SP361.7

http://sp.lyellcollection.org/content/361/1/79/tab-figures-data

- PVMBG & BNPB

- photos: Øystein Lund Andersen and Kumparan - by Dicky Adam Sidiq

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