volcanic news

One of the most important finds ever made in the western region of Lesvos and its petrified forest has been unearthed as part of excavations carried out in the area of ​​the intersection leading to the Natural History Museum and the petrified forest of Sigri.

"A fossil has been identified which is one of a kind. It is an entire tree with its branches almost intact, as when it died. We also found numerous leaves around the main find as well as its root system. The whole was protected by volcanic ash from an eruption dated 23 million years ago "says the director of the Sigri Forest Museum.

The island of Lesvos is located in the northeast of the Aegean Sea. Its surface area is 1,632 km², including 320 km of coastline. It is the third largest Greek island. The Strait of Mytilene separates it from Asia Minor and the Turkish coasts, to which it was attached until the end of the Paleolithic, before the end of the last Ice Age.

Lesvos is a hilly island with higher peaks: Lepetimnos (968 m), Olympos (967 m) and Psilokoudouno (914 m).
It is characterized by volcanism in the Miocene and was created from two volcanoes that are no longer active. The original volcanic cones have disappeared under the water, leaving two bays: the largest bay is the Gulf of Kalloni and measures approximately 20 x 8 kilometers and to the southeast the smaller bay, the Gulf of Gera, measures approximately 10 x 5 kilometers. Researching with satellite images, scientists discovered 5 additional craters, near Stipsi, Vatousa, Antissa, Agra and Mesotopos.

During drilling, they determined that the geothermal heat at depths of up to 1,000 m was about 100 ° C. This geothermal energy is used, among other things, to heat greenhouses. There is still latent volcanic activity on Lesvos. Hot springs rise to the surface in five places, in Eftalou, Thermi, Gera, Polichnitos and Lisvori.

The island is largely made up of volcanic rocks. Only the area to the south, above Plomari, has pre-volcanic rocks: slate, gneiss and quartz, about 300 million years old.

Lesbos geosites (Doc. Geomorphology of Dodecanese)

1: Petrified Forest park; 2: Nissiopi park; 3: Sigri park; 4: Plaka park; 5: Skamiouda park; 6: fossiliferous site of Antissa; 7: Mesotopos fossil site; 8: fossiliferous site of Eressos; 9: Rougada fossil site; 10: fossiliferous site of Molyvos-Petra; 11: Lapsarna fossil site; 12: Chamandroula fossil site; 13: Gavathas fossil site; 14: fossiliferous site of Vatera; 15: Metohi fossil site; 16: Akrohiras fossil site; 17: Mavros Lofos fossil site; 18: Sarakina fossil site 19: Lepetymnos caldera; 20: Vatoussa caldera; 21: Agra caldera; 22: dome of Mesotopos; 23: dome of Ipsilou; 24: volcanic neck of Petra; 25: basaltic organs of Panagia; 26: Alifada's dyke; 27: Filia dyke; 28: basalt columns of Anemotia; 29: dome of Eressos; 30: basaltic organs of Pelopi; 31: basaltic organs of Molyvos; 32: Achladeri ignimbrites; 33: Gera thermal spring; 34: thermal spring of Thermi; 35: Lisvori thermal spring; 36: thermal spring of Polichnitos; 37: thermal spring of Argenos; 38: thermal spring of Eftalou; 39: spherical erosion forms of Vatoussa; 40: cliffs of Lapsarna; 41: gorges of Voulgaris; 42: Antissa cave; 43: Taxiarhon cave; 44: cave of Mihos; 45: cave of Alifada; 46: Faneromeni folds; 47: fault in the Gulf of Gera; 48: Larsos fault; 49: Agia Paraskevi fault; 50: Olympos tectonic window; 51: Vatera fault; 52: old Moria quarry; 53: mines north of Lesvos; 54: magnesite mines.

The petrified forest of Lesbos :

The Sigri pyroclasts, the densest in the west of the island, are covered by several layers of Polichnitos ignimbrite, dated to around 17.0 Ma.

The fossilized tree trunks of the Petrified Forest appear in the thick "Sigri pyroclastic sequence".

This formation consists of several horizons of pyroclastic flows, mainly pumice flows, mud flows, debris flows and stream conglomerates interspersed with pyroclastic deposits.

The magma intrusion caused the western flank of the Vatoussa volcano to collapse in an avalanche of debris, leaving a horseshoe-shaped caldera.

The explosive phases seem to have been very strong, as shown by the distribution of the eruptive products. The pumice phase was probably ejected to a great height before falling on the sides of the volcano and its surroundings. A blast of hot gas preceded the avalanche of debris, flattening thousands of trees which were later covered with pyroclastic material.

This caused the amputation of the majority of the trees one or two meters above the ground surface. Today, the upper parts of tree trunks lie horizontally, buried in pyroclastic layers. The comparable catastrophic 1980 eruption of St. Helens in the United States helps to understand the mechanism of the Vatoussa volcano eruption and to give some idea of ​​its effects.

The rapid covering of tree trunks, branches and leaves led to their isolation from atmospheric conditions. Along with the volcanic activity, hot solutions rich in silica penetrated and permeated the volcanic materials that covered the tree trunks. Thus, the major process of fossilization began with an exchange, molecule by molecule, of the chemical constituents of the plant, from organic to inorganic (quartz), while maintaining the tissue structures.

Sources:

- Stonisi - Lesvos environment - discovery of a fossilized tree, with its branches, 20 million years old

- Géomorphologie - Assessment, protection, and promotion of geomorphological and geological sites in the Aegean area, Greece - N. Zouros.

- The Plaka petrified forest park in western Lesvos - by Zouros N. & al.

In Yellowstone National Park, the "Old Faithful" geyser in the Upper Geyser Basin received its unique name in the 19th century due to the regularity and predictability of its eruptions.

A sample of mineralized (silicified) wood was discovered in his mouth, as evidenced by a Journal published over 60 years ago. Its radiocarbon dating has just been confirmed in a study that was just published in October 2020, on 41 dates: 1233-1362 CE.

This date corresponds to a series of severe regional droughts, which lasted for many decades, at the end of the Middle Ages climate anomaly, before the onset of the Little Ice Age.

Murray pines (Lodgepole pine) were able to thrive in the mouth of an active natural geyser only during a period of great drought that affected much of the United States, and affected the native cultures of Anasazi, Fremont and Lovelock . The remains of trees were then preserved by mineralization in an alkaline water rich in silica ... to reveal to us today the mysteries of the "Old Faithful".

Natural geysers are rare on the planet, because they require special conditions to form: heat input from active or recent magmatism, and adequate geometry of rock fractures underground to ensure episodic discharge. These parameters can change following earthquakes modifying the fractures, or by regional variations in precipitation, which feed underground reservoirs.

Climate change forecasts, which include regional droughts for the middle of the 21st century, suggest less frequent eruptions of these geysers, and even the end of their activity.

Happy are those who were able to see them in great shape!

Sources:

- USGS - Caldera chronicles - A time when Old Faithful wasn’t so faithful

- Geophysical Research letters - Yellowstone's Old Faithful Geyser Shut Down by a Severe 13th Century Drought

Dernière semaine de la série " Des volcans et des hommes ",  sur Arte tv.

Le rendez-vous est à 17h35, avec au programme :

- Lundi 8 avril : Guatemala, des volcans en terre Maya.

- Mardi 9 avril : Islande, les seigneurs du feu.

- Mercredi 10 avril : Mauna Loa, le géant d'Hawaii.

- Jeudi 11 avril : Nouvelle-Zélande, lacs volcaniques en terre maorie.

- Vendredi 12 avril : Equateur, les irréductibles du Tungurahua.

Pour ceux qui auraient raté un épisode la semaine passée, voici les liens sur Arte Replay (merci à Damien Becquart pour les liens)

- Iles éoliennes  : https://www.arte.tv/fr/videos/069786-010-A/des-volcans-et-des-hommes-iles-eoliennes/

- Nouvelles Zélande : https://www.arte.tv/fr/videos/069786-003-A/des-volcans-et-des-hommes-nouvelle-zelande-des-tresors-pour-les-hommes/

- La Réunion : https://www.arte.tv/fr/videos/069786-011-A/des-volcans-et-des-hommes-la-reunion-au-coeur-des-volcans/

- Le Guatemala : https://www.arte.tv/fr/videos/069786-015-A/des-volcans-et-des-hommes-guatemala-des-volcans-en-terre-maya/

- Le Sakurajima : https://www.arte.tv/fr/videos/069786-013-A/des-volcans-et-des-hommes-sakurajima-une-vie-sous-les-cendres/

Bonne semaine sur les volcans du monde.

On Barren Island, in the Andaman Islands, the activity is characterized by lava fountains feeding a northward flow.

The thermal anomaly was reinforced on October 22, with 217 MW measured by Mirova.

Sources: Mirova and local observers

In Alaska, the instability that characterizes the Veniaminof continues.

The seismicity is above base levels, with a peak of the RSAM on October 21st, and there is a continuous low level tremor.

On satellite images, the volcano has high surface temperatures, and nighttime glow is visible on the Perryville webcam; during the day, these persistent emissions of steam are observed.
 

Sources: AVO, Sentinel 2 and Mirova

The Arenal Volcano shows an increase in the degassing of crater C, which is where the last eruptions were given. This degassing sometimes reaches more than 300 meters above the level of the crater and is visible from several points of San Carlos.
This activity corresponds to reports from people who have been at the top, and who report that in recent days they have been dizzy, there is little air and the gas is suffocating, perhaps because of carbon dioxide ( CO₂), which is liberated in depth by the magmatic systems. In addition, there have been small earthquakes that indicate internal activity.

Source: VSF / Volcanoes Sin Fronteras 21.10.2018

At Dukono, on the island of Halmahera, eruptive activity continues; despite the fact that volcano emissions are not identifiable in the Himawari satellite images, the Darwin VAC has issued an ash dispersion advisory for this October 22nd.

Copernicus reports the availability of the information provided by Sentinel 5Ps gas emissions on open access, which is reflected in a picture of Dukono's sulfur dioxide emissions.

Sources: VAAC Darwin and Sentinel 5P

 Dukono - Sentinel 5P (SO2) data is available Open Access Hub Copernicus

An interesting document on the explosions and sounds of gas output in "train machine" was posted by Martin Rietze, illustrating the activity of Sangeang Api.

Source: Video by drone Martin Rietze.

At Veniaminof, a small activity continues this week at the intracaldeira cone. The western branch of the lava field on the southern flank remains active.

Constant steam emissions can be seen on the Perryville webcam.

On October 18, the emissions were particularly strong, with a plume dominated by steam, with the presence of sulfur dioxide and a small amount of ash, and extending for 30 km to the northeast.

The effusion of lava continues, as indicated by a relatively continuous tremor.

The Veniaminof remains in Volcanic Alert Watch and Orange Aviation Code

Source: AVO

The images provided by Tropomi show significant sulfur dioxide emissions at Ambrym volcanoes in Vanuatu, and the interaction of the plume on Malekula Island, further west with more than 20,000 inhabitants.
 

An image of Caliop / Nasa determined the height of the July 30, 2018 sulfur-containing aerosol cloud in the stratosphere, impacting a large area.

Four lava lakes are currently active on the island.

Sources: AIRES, Tropomi, Nasa Caliop via Simon Carn.

At Merapi, the phase of effusive activity continues: the dome reaches 18 October a volume of 201,000 m³, with a daily rate of growth rising to 6,200m³. The small lobe of the dome on the north side seems to progress.

The dome is considered stable for the moment, and the level of activity remains at 2 / Waspada, with a forbidden zone of 3 km radius around the summit.

Source: PVMBG

The Gunung Dukono, on Halmahera, in activity level II / Waspada, with a 2 km forbidden zone, is in constant eruption.

From yesterday to this morning, the summit of the volcano was observed visually until it was covered with mist. The plume is white to gray, thick, reaching 500 m above the summit.

The seismographs recorded on October 18th: 5 earthquakes of eruption and the continuous tremor with an amplitude of 0,5-15 mm (dominant 2 mm)

The last VONA is of ORANGE color, issued on October 18, 2018 at 12:04 WIT, relating to the eruption with an ash plume of a height of about 1729 m above sea level or about 500 m above the sea level. Mountain peak. The ash column moves east.

The Gunung Ibu, on Halmahera also in activity level 2 / Waspada, with a "no go zone" of 2km stretched 3.5 km north side, has been erupting continuously since 2008.

From yesterday to today, a white to gray plume is observed at a height between 200 and 600 meters above the summit.

Seismicity remains important, with 17 episodes of harmonic tremor on 18.10.

The VONA has been orange since October 6th.

Sources: PVMBG & VAAC Darwin

At the Piton de la Fournaise, the intensity of the volcanic tremor (indicator of the eruptive intensity at the surface) is still very slightly decreasing.

Inflation (swelling) of the building is always recorded. This inflation reflects the pressurization of a localized source beneath the summit craters (Bory-Dolomieu) at a depth of 1-1.5 km, related to the recharge of the superficial reservoir by deeper magma.

The surface flow rates could not be estimated today because of lava flows that are too weak at the surface.

A field reconnaissance has been completed today. The observations show a surface activity still very limited. Strong degassing is always observed at the eruptive vent. Some resurgences and a small channel of a few tens of meters were visible this morning around 11:30 at the foot of the eruptive cone (eastern sector).

Source: OVPF - Find all the information related to the activity of the Piton de la Fournaise on the different media of the OVPF-IPGP:

- the website (http://www.ipgp.fr/fr/ovpf/actualites-ovpf),

- the Twitter account (https://twitter.com/obsfournaise?lang=en),

- and the facebook account (https://www.facebook.com/ObsVolcanoPitonFournaise/)

The information in this document may not be used without explicit reference.

Sernageomin has reduced the alert level of two volcanoes, Osorno and the Puyehue - Cordon Caulle complex, from Amarilla to Verde, following a decrease in their internal activity.

A bit of everything in the absence of news of eruptions ...

At Piton de La Fournaise, the eruption started on September 15th at 4:25 am local time continues. The intensity of the volcanic tremor (indicator of eruptive intensity at the surface) is still very slightly decreasing.
The pistons have disappeared gradually, and since this morning 03:45 local time, no more gas piston ("gas puff" or "puff of tremor") is recorded at the eruptive site.

The Reunion Island Air Quality Observatory (ATMO REUNION) recently recorded a concentration of sulfur dioxide (SO₂) particles at Saint-Joseph and Buffon. These transient episodes took place between Tuesday 9 and Thursday, October 11, 2018 (observation stations "Grand Coude" and Bourg Murat). The probable origin of this episode is related to the eruption of the Piton de la Fournaise and to the current weather conditions. During these episodes, the threshold of 300 μg / m3 / h of SO₂ was exceeded for a limited time (1 to 2 hours).

During episodes, it is recommended that vulnerable or sensitive people limit intense physical or sports activities, including competitions, both outdoors and indoors.

Sources: OVPF and Imazpress

Retrouvez l’ensemble des informations relatives à l’activité du Piton de la Fournaise sur les différents médias de l'OVPF-IPGP:

- le site internet (http://www.ipgp.fr/fr/ovpf/actualites-ovpf),

- le compte Twitter (https://twitter.com/obsfournaise?lang=fr),

- et le compte facebook (https://www.facebook.com/ObsVolcanoPitonFournaise/)

Les informations de ce document ne peuvent être utilisées sans y faire explicitement référence.

At Kilauea, the eruption is not relevant ... the strain, seismicity and gas emission ratios have not changed substantially over the past week.

The HVO finds weak seismic measurements at the summit and on the southern flank of Kilauea; they are small replicas of the magnitude 6.9 earthquake of May 4, 2018. Seismicity remains low in the East rift zone.

The deformation signals show a recharge of the median East rift zone.

The low levels of sulfur dioxide emitted result in a significant decrease in VOG (Volcanic Air Pollution) and clear the view of Mauna Loa and Mauna Kea from the lava fields of the rift zone.

For the beauty of the shooting: The first place in the National Geographic category competition was won by photographer Karim Ilya, with a photo of the lava flow from the penultimate eruption, arriving at sea.

Sources: HVO, USGS and National Geographic

New excavations on the site of Pompei / Regio V allowed to accurately repeat the eruption of Vesuvius.

This dating was until now based on the writings of Pliny the Younger to his friend Tacitus, who set the disaster on August 24, 79.

The discovery of a charcoal graffiti, mentions: " XVI K NOV ", or the 16th day before the calends of November (the calends were the first day of each month in the Roman calendar), which corresponds to October 17 of the modern calendar.

It supports another discovery: calcified branches bearing berries, normally present in autumn.

This discovery was presented by the head of the Pompeii site, in the presence of the Minister of Culture.

Sources: Antigua Roma: El grafito cambió the fecha of the destruction of Pompeya

Activity on Kadovar in Papua New Guinea is relatively little documented by the observatories.

Since September, it seems to concern only the summit, no plume coming out of the coastal dome.

The Sentinel 2 images show white top degassing on September 12, and on September 22, more intense.

On the images of September 22, September 27, and October 10, it is found that the west side of the island, which had greened, is covered with ashes.

A notice of ash dispersal is issued on 28 September by VAAC Darwin.

On October 12, the plumes of ashes succeed one another, leaving a rosary of clouds towards the west, always coming from the summit.

Thermal anomalies are reported by Mirova on 14 and 15 October, respectively 17 and 22 MW.

It should be noted that the Rabaul volcano Observatory reports an increase in activity on 21 September, remaining high until 26 September; Gray and brown plumes are observed several hundred meters above the summit crater, drifting to the northwest. Incandescence is reported from the main crater, southeast costal vent and other areas.

Small amounts of ash fell on Blup Blup Island.

On October 1, a plume rises to 900 meters asl, drifting westward; and on October 3, a cloud of ash is observed by satellite, drifting westward at an altitude of 2,100 meters asl. (in GVP)

Sources: Sentinel 2, VAAC Darwin and RVO / Global volcanism Program weekly report 

The Ovsicori reports an eruption on October 15 at 5:42 am at Turrialba, lasting a few minutes and accompanied by a plume of gas and ash rising to 1,000 meters above the crater.

The seismographs recorded another explosion signal at 6:16.

Subsequently, passive emissions at a hundred meters above the crater occurred.
 

Source: Ovsicori

The assessment of the Sulawesi / Palu earthquake of September 28 has been revised ... still on the rise, unfortunately.

As of 15 October, there are 2,100 dead, 4,612 seriously injured, 680 missing, and 78,994 displaced persons.

Source BNPB

The eruption started a month ago at Piton de La Fournaise continues. The intensity of the volcanic tremor (indicator of eruptive intensity at the surface) is still very slightly decreasing.
Gas pistons  ("gas flushes" or "tremor puffs") at the eruptive site are always recorded by the OVPF seismometers.

Inflation (swelling) of the building is always recorded. This inflation reflects the pressurization of a localized source beneath the summit craters (Bory-Dolomieu) at a depth of 1-1.5 km, related to the recharge of the superficial reservoir by deeper magma.

A field reconnaissance was completed today. In the maintenance program and repairs of measuring stations, and samples of lava at 600m from the front of the casting.
Most of the activity is still conducted in lava tunnels, no major channel was observed and only small and rare resurgences were visible. No projections were observed at the eruptive cone and the level of the lava lake inside the vent was relatively low. A strong degassing was still present at the level of the vent as well as at the level of the main lava tunnel located just downstream

Many visitors have waited until the lava flows are visible since the Grand Brûlé, but today it is a huge disappointment that its flows on the heights of the big slopes have frozen.Il should surely a new rise of the flow of lava or a new eruption lower to see this magnificent show.

An image of the Sentinel 2 satellite of October 14 shows, thanks to the filters used, a hot spot in the active cone and another at the casting front, near the rampart

The flow front has not evolved since the last sightings and was this morning still 500m from the Great Slopes, the latter was completely frozen.

Source: OVPF - Find all the information related to the activity of the Piton de la Fournaise on the different media of the OVPF-IPGP:

- the website (http://www.ipgp.fr/fr/ovpf/actualites-ovpf),

- the Twitter account (https://twitter.com/obsfournaise?lang=en),

- and the facebook account (https://www.facebook.com/ObsVolcanoPitonFournaise/)

The information in this document may not be used without explicit reference.

On 14 October, the Etna seismic network recorded an increase in the level of the volcanic tremor and seismic signals from the INGV-OE station.

The weather conditions did not allow to have a vision on the current activity.

On the morning of October 15th, the images of the LAVE webcam allow to see fumaroles under the summit, probably in connection with a small lava flow.

Correction: The steam seen on the LAVE webcam was not due to a new lava flow, but well produced by the rain falling on an old lava flow lane cooling (thanks to Pippo Scarpinati for this clarification) 

Sources: INGV seismograms and LAVE Webcam

The Sangeang Api, which forms a small island 13 km wide in the Lesser Sunda islands, off Sumbawa, is in episodic activity.

Beautiful photos of his Strombolian activity between 28th and 30th September have just been put on line on the page Volcanoes and volcanism / Facebook by Martin Rietze ... superb as always!

Source: Martin Rietze / Volcanoes and volcanism

The eruption started at Piton de La Fournaise on September 15th at 4:25 am local time continues. The intensity of the volcanic tremor (indicator of eruptive intensity on the surface) is always slightly lower.
Gas pistons ("gas flushes" or "tremor puffs") at the eruptive site are always recorded by the OVPF seismometers.

No volcano-tectonic earthquake was recorded during the day of 12 October, nor of the 13th.
Inflation (swelling) of the building is still recorded even though it seems to have slowed down for three days. This inflation reflects the pressurization of a localized source beneath the summit craters (Bory-Dolomieu) at a depth of 1-1.5 km, related to the recharge of the superficial reservoir by deeper magma.
Surface flow rates could not be estimated today because of poor surface flow and cloud cover on site.
Observations made on the evening of October 12th from the observatory's webcams (aiming in particular at the base of the Tremblet's Nez Coupé), during a gap in the cloud cover, showed that the flow front did not seem to have progressed significantly since the last observations of October 08 (before the deterioration of weather conditions on site) and was maintained at the top of the Great Slopes.

Some beautiful images of the lava flows, filmed in the rain on September 30, ... in the absence of photos of the last days due to bad weather.

Sources:

- OVPF - 

Retrouvez l’ensemble des informations relatives à l’activité du Piton de la Fournaise sur les différents médias de l'OVPF-IPGP:

- le site internet (http://www.ipgp.fr/fr/ovpf/actualites-ovpf),

- le compte Twitter (https://twitter.com/obsfournaise?lang=fr),

- et le compte facebook (https://www.facebook.com/ObsVolcanoPitonFournaise/)

Les informations de ce document ne peuvent être utilisées sans y faire explicitement référence.

- Video from Ced Northman, whom I thank for sharing.

Beautiful lava flows ... we want more !

The "Caverne Gendarme" lava tunnel, located at the Brûlé from the table to the Îlet aux Palmistes / commune of St Philippe, constituted the framework of tests of Comex space with a view to lunar expedition. This tunnel developed in a casting dated 18th century outside caldera.

A summary of these tests is visible on the Imazpress / Objectif Lune website: the island could host astronauts.

The growth of the Merapi dome is continuing ... on 11 October, the volume of the dome was 158,000 m³, with a daily growth rate of 3,100 m³, a little higher than at the end of September.

The dome is described as stable, although there is a slight outpouring on the north side.

It is marked by a thin, white fumarole 70 meters above the summit.

The activity level remains at 2 / waspada, with a prohibited area of ​​3 km.

Sources: PVMBG & Magma Indonesia

In Fuego, the rise in activity level has no duration.

The RSAM shows a decrease on 13 October, and weak to moderate explosions with a lower ash column, then relayed by a white degassing from a height of 1,000 meters above the summit, and a lava flow in the Barranca Seca of reduced length to about 200 meters according to the Conred.

Evolution to follow

Sources: Insivumeh 13,10,2018 / 10h local and Conred

At Turrialba, the Ovsicori reports an eruption on October 13 from 7:50 am, accompanied by a plume of ash 500 meters above the active crater. The activity is in progress.

Source: Ovsicori