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Earth of fire

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

actualites volcaniques

Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
NOAA and the University of New Hampshire will perform a mapping expedition of the  Mendocino ridge, off the Pacific coast of California, between September 23 and October 12.


Obtaining detailed framework should contribute to a better understanding of the geological processes at an active plate boundary.




 

The North American, the Pacific and the Gorda plates - the Mendocino Ridge in the white box - Doc. NOAA / CCOM

The North American, the Pacific and the Gorda plates - the Mendocino Ridge in the white box - Doc. NOAA / CCOM

The Mendocino Ridge is a narrow structure on the seabed, coupled with the Mendocino fracture zone, which stretches more than 5,000 km away. in the eastern Pacific Ocean. North of the Mendocino Ridge, the Gorda plate dives under the North American plate along the Cascadia subduction zone. Near Cape Mendocino, three tectonic plates, the Pacific Plate, Gorda plate and the North American plate, come together to form a "triple junction point" migrating northward.

 

The North American, Pacific and Gorda plates, with the direction and the speed of the  movement  - Doc.GVP

The North American, Pacific and Gorda plates, with the direction and the speed of the movement - Doc.GVP

Portion of the dorsal Mendicino, with volcanoes whose status is not yet known - Doc. NOAA ocean explorer

Portion of the dorsal Mendicino, with volcanoes whose status is not yet known - Doc. NOAA ocean explorer

Mendocino ridge - 3D view of the southwest side of a submarine unnamed volcano - Doc. Center for Coastal and Ocean Mapping. - NOAA

Mendocino ridge - 3D view of the southwest side of a submarine unnamed volcano - Doc. Center for Coastal and Ocean Mapping. - NOAA

The research vessel Atlantis, from the Woods Hole Oceanographic Institution, discovered around  the ridge an area rich in small volcanoes and mounds (smaller than Seamont structure, and between 500 and 1,000 meters).

Among these mounds, the bathymetry shows a round-shaped structure like an underwater volcano, 7 km from basal diameter, having slopes estimated at 40 °, located at 400 nautical miles NW of San Francisco. She has not been named yet.

Mendocino ridge - a rising gas plume from an structure in amphitheater - Image courtesy of NOAA-University of New Hampshire.

Mendocino ridge - a rising gas plume from an structure in amphitheater - Image courtesy of NOAA-University of New Hampshire.

In 2009, the NOAA's ship Okeanos Explorer  revealed, north of the Mendocino ridge , a methane plume rising about 1,400 meters above a large depression in amphitheater on the ocean floor.

 

Sources :

- Return to Mendocino Ridge: U.S Extended Continental Shelf Project, Exploratory Mapping Expedition - link

- Center for coastal and ocean mapping joint Hydrogrephic center  - Return to Mendocino Ridge - link

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques

According to the report of the Scientific Committee of Civil Defence on 10 October, during the past week, the eruption of Holuhraun continues with a similar intensity and the same lava flows than the previous week. Seismicity is low in the northern part of the dyke and the eruptive site.

The lava field now reaches more than 50 square kilometers. One radar image made by the SAR-X Terra satellite on October 7 gives us an accurate picture of the lava field, between the north-east of Vatnajökull and the caldera of Askja. The lava flow appear clear due to its rough structure, and the most active channel darker because a smoother surface.

Radar image of the lava field Holuhraun, taken on October 7 by the SAR-X satellite Terra - the Askja caldera in the upper left corner - Doc. (c) DLR / Fjarkönnun ehf. / IsViews 10/2014. / Via IMO.

Radar image of the lava field Holuhraun, taken on October 7 by the SAR-X satellite Terra - the Askja caldera in the upper left corner - Doc. (c) DLR / Fjarkönnun ehf. / IsViews 10/2014. / Via IMO.

The same day, the lava field map, based on previous observations and Modis image - 07.10.2014  - doc picture. IES

The same day, the lava field map, based on previous observations and Modis image - 07.10.2014 - doc picture. IES

The air pollution by sulfur dioxide affected the southwest of Iceland from October 7 to 9. It is expected on the same area Saturday. An interactive map is available on the website of the Met Office.

In addition to the measurements on the eruptive site by the scientists, others as part of the project FutureVolc, automatic stations make mesurements that show a strong increase between Reykjavik and the eruption site on 10 October, with a peak at 2400μg / m³ around 4:15 p.m..

All of the instructions remain the same: "if incomfort, it is advised to stay inside, with doors and windows closed, shutting off the air conditioning and heating more strongly, so as to create a pressure difference favorable. Ventilate the house during periods of good air quality. If difficulties, contact health centers ".

 

2014.10.10 - Sky of SO2 pollution - photo Lukas Gawenda / Der Spiegel

2014.10.10 - Sky of SO2 pollution - photo Lukas Gawenda / Der Spiegel

Map of pollution on the southwest of Iceland on 10/10/2014 / 13h - doc IMO

Map of pollution on the southwest of Iceland on 10/10/2014 / 13h - doc IMO

 2014.10.10 - rising rates of SO2 to Þjórsárdalur, SE of the eruption, from 11am, with a peak around 16h15 - doc.

2014.10.10 - rising rates of SO2 to Þjórsárdalur, SE of the eruption, from 11am, with a peak around 16h15 - doc.

2014.10.09 - "Red Sun over Reykjavik", due to the presence of sulfur dioxide in the atmosphere - photo © mbl.is - Golli

2014.10.09 - "Red Sun over Reykjavik", due to the presence of sulfur dioxide in the atmosphere - photo © mbl.is - Golli

To the Bárðarbunga, the subsidence of the caldera continues at the same rate.

Thirteen earthquakes above magnitude 3.0 have been recorded since Wednesday midnight in and around the caldera, the most important to 3:24 p.m. Wednesday and at 9:22 p.m. on 9 October.

Subsidence of the caldera Bárðarbunga between 8 and 10/10/2014 / earthquake magnitude over the same period - Doc. IES

Subsidence of the caldera Bárðarbunga between 8 and 10/10/2014 / earthquake magnitude over the same period - Doc. IES

Sources :

- Icelandic Met Office / IMO

- University of Iceland / IES

- Iceland Review

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques

The eruption of Gunung Sinabung, which has been ongoing since September 2013, seems to reactivate in October.

The BNPB reported four eruptive episodes, accompanied by pyroclastic flows on October 5. The first at 1h46 with a long cast of 4,500 meters and co-pyroclastic plume reaching 2,000 meters. The other three, respectively at 6h38,7h36 and 7h53, generated pyroclastic flows of a length between 2,500 and 4,500 meters, and plumes rising to 3,000 m. Press mentions two other episodes at 9h and 12 o'clock.


 

 2014.10.05 / 12:33 - Sinabung - photo Mbah Lewa

2014.10.05 / 12:33 - Sinabung - photo Mbah Lewa

The Jakarta MVO notes plume reaching 5,200 meters and drifting southward on October 7.

The corridor used by the pyroclastic flows is a little west of the previous lava flow; the topography is different in this place ... the steep slope allowing to a significant acceleration of the flows, likely fueled by a more gas-rich magma. The affected area extends further southwest, threatening the village of Payung at the boundary of the area of 5 km.

The press reports of consecutive evacuations these pyroclastic flows.

The webcam of the VSI and Twitter regularly provides images of the pyroclastic flows of 8 and 9 October.

 

Map of areas at risk from 2013 to Sinabung - in red: impactable area by pyroclastic flows ( to extend) - in pink: touchable area by falling ash - in yellow: areas at risk of lahars. - Doc. BNPB

Map of areas at risk from 2013 to Sinabung - in red: impactable area by pyroclastic flows ( to extend) - in pink: touchable area by falling ash - in yellow: areas at risk of lahars. - Doc. BNPB

 Pyroclatic flow of the Sinabung 07.10.2014 / 2:08 p.m. - photo Mbah Lewa

Pyroclatic flow of the Sinabung 07.10.2014 / 2:08 p.m. - photo Mbah Lewa

Sinabung - locals seem indifferent to the volcanic activity - photo 2014.10.08 Martin Ledanto Sinulingga

Sinabung - locals seem indifferent to the volcanic activity - photo 2014.10.08 Martin Ledanto Sinulingga

 Sinabung 8 October 2014 - Photo REUTERS - YT Haryono

Sinabung 8 October 2014 - Photo REUTERS - YT Haryono

Sinabung on 08.10.2014 / 10:44 p.m. - starting of the flow and formayion of the co-pyroclastic plume - photo Mbah Lewa

Sinabung on 08.10.2014 / 10:44 p.m. - starting of the flow and formayion of the co-pyroclastic plume - photo Mbah Lewa

Sinabung on 08.10.2014 / 10:47 p.m. - heat and turbulence of the pyroclastic flow - photo Mbah Lewa

Sinabung on 08.10.2014 / 10:47 p.m. - heat and turbulence of the pyroclastic flow - photo Mbah Lewa

Sinabung - two images of the webcam 09/10/2014, 6:38 ET 10:24 respectively - one click to enlarge - doc. VSISinabung - two images of the webcam 09/10/2014, 6:38 ET 10:24 respectively - one click to enlarge - doc. VSI

Sinabung - two images of the webcam 09/10/2014, 6:38 ET 10:24 respectively - one click to enlarge - doc. VSI

Pyroclastic flow of the Sinabung 2014.10.09 / 11:05, from Payung ...it approaches dangerously of this area - Photo Yudhi - volcano observatory staff / via Twitter.

Pyroclastic flow of the Sinabung 2014.10.09 / 11:05, from Payung ...it approaches dangerously of this area - Photo Yudhi - volcano observatory staff / via Twitter.

Ash fallout disrupts the city of Berastagi, located 23 km from the volcano. The rural economy is paralyzed and many traders have closed their shops for fear of their goods and fruits / vegetables are covered by ashes. The administration and schools continue to operate, staff and students wearing masks.
 

MAS, AirAsia and Firefly airlines of Medan canceled flights this 09.10. because of the ash  emitted by the volcano.

The alert level remained at 3, despite this increase in activity. According to Mr Putra, head of the observation post to Sinabung, the transition to the next level would result in forced evacuations.

 

Sources :

- Badan Nasional Penanggulangan Bencana  - BNPB – link

- Global Volcanism Program - Sinabung / weekly report - link

- médias : Jakarta Post / Jakarta Globe 

- réseaux sociaux : Twitter et Facebook

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
For the first time, a correlation was established between tephra found in northern Germany - tephra "AD860B" - and North America - "The White River ash".


These tephra were previously identified in Greenland, Norway, Scotland and Ireland in other studies.

 Mount Bona-Churchill, in the St. Elias mountains in Alaska - photo Skimountaineer.

Mount Bona-Churchill, in the St. Elias mountains in Alaska - photo Skimountaineer.

Volcanoes and glaciers of the Wrangell / St. Elias in Alaska group

Volcanoes and glaciers of the Wrangell / St. Elias in Alaska group

The White River Ash :

Ash, that belong to the same eruption, refer to that of Mt Bona-Churchill, located in the St. Elias Mountains in Alaska, and dating from the year 843.

The ash deposits, bilobed, of the White River covers over 340,000 square kilometers in Alaska and Canada (Yukon and Northwest). These deposits correspond to two rhyodacitic Plinian eruptions, different, under the influence of strong unidirectional winds, dated by the GVP of 60 AD +/- 200 years and  800 AD +/- 100 years.

Both eruptions are classified as an explosive 6 The last issue, here index, is more important for the volume of tephra emitted: 30km³ for the East lobe, issued in winter and prevailing winds eastward direction. The north lobe is estimated to correspond to a volume of 20 cubic kilometers of tephra, issued in the summer, when winds northward dominates (from West, KD & Donaldson, JD -2000).

Source and location of deposits of pumice from the "White River ash" - Doc. Yukon Geological Survey - Top inset : the two lobes corresponding to the two Plinian eruptions - Bottom inset: location of the zones of proximal pumice and pumices terraces along the Klutlan glacier.

Source and location of deposits of pumice from the "White River ash" - Doc. Yukon Geological Survey - Top inset : the two lobes corresponding to the two Plinian eruptions - Bottom inset: location of the zones of proximal pumice and pumices terraces along the Klutlan glacier.

White River ash eastern lobe - Tectonic - Doc. Natural Resources Canada / Blast from the past

White River ash eastern lobe - Tectonic - Doc. Natural Resources Canada / Blast from the past

White River ash eastern lobe / Yukon: left, very vesiculated ash particle (. Gross 1200 x) extended by the violence of the conditions at the time of the eruption in the year 800 - Doc. Yukon Geological Survey - right : road embankment exposing a clear layer of 10 cm. thickness of the White River ash - A click to enlarge - photo P. Sinclair / Natural Resources Canada.White River ash eastern lobe / Yukon: left, very vesiculated ash particle (. Gross 1200 x) extended by the violence of the conditions at the time of the eruption in the year 800 - Doc. Yukon Geological Survey - right : road embankment exposing a clear layer of 10 cm. thickness of the White River ash - A click to enlarge - photo P. Sinclair / Natural Resources Canada.

White River ash eastern lobe / Yukon: left, very vesiculated ash particle (. Gross 1200 x) extended by the violence of the conditions at the time of the eruption in the year 800 - Doc. Yukon Geological Survey - right : road embankment exposing a clear layer of 10 cm. thickness of the White River ash - A click to enlarge - photo P. Sinclair / Natural Resources Canada.

The study of Britta Jensen, a geologist at Queen's University in Belfast, and his team (in GEOLOGY 2014.07- Transatlantic Alaskan distribution of the White River Ash) shows that the ash from an only eruption of VEI 6 are able be spread out over 7000 km., according to records and analyzes made in marine, terrestrial and ice.

Such "small eruptions" can therefore have a significant impact on our technological society, and severely disrupt transatlantic air routes ... so that such distribution of ashes was regarded up to now as exceptional and in conjunction with supereruptions.

Map of locations of samples analyzed in 2014 (stars) and other  during previous studies (circles) -- Crawfish Inlet (Alaska; Addison et al., 2010), Nordan’s Pond Bog (Newfoundland; Pyne-O’Donnell et al., 2012), and sites S1 and S2, two examples of a more comprehensive list of sites in Europe from Lawson et al. (2012). Est.—estimate; NGRIP—North Greenland Ice Core Project; NEEM—North Greenland Eemian Ice Drilling; QUB—Queen’s University Belfast; JAM—Jardelunder Moor; DOM—Dosenmoor. The lack of sites between proximal samples and eastern Canada reflects the absence of cryptotephra studies in this region. / doc. in Jensen B.& oth.

Map of locations of samples analyzed in 2014 (stars) and other during previous studies (circles) -- Crawfish Inlet (Alaska; Addison et al., 2010), Nordan’s Pond Bog (Newfoundland; Pyne-O’Donnell et al., 2012), and sites S1 and S2, two examples of a more comprehensive list of sites in Europe from Lawson et al. (2012). Est.—estimate; NGRIP—North Greenland Ice Core Project; NEEM—North Greenland Eemian Ice Drilling; QUB—Queen’s University Belfast; JAM—Jardelunder Moor; DOM—Dosenmoor. The lack of sites between proximal samples and eastern Canada reflects the absence of cryptotephra studies in this region. / doc. in Jensen B.& oth.

Sources :

- Geology - Transatlantic distribution of the Alaskan White River Ash - by Britta Jensen & others - link

- Global Volcanism Program - Churchill

- AVO-USGS - Mt. Churchill

- Mt. Churchill, Alaska : source of the late holocene white River Ash - by D.H. Richter & al.

- Evidence for winter eruption of the White River Ash (eastern lobe) Yukon territory Canada - by K.D. West & J.D. Donaldson

- Natural Resources Canada - Blast from the past 

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques

These fossilized footprints were discovered accidentally in 1919 by a geologist, Ruy H. Finch, working at the Hawaii Volcano Observatory, in the desert ash Ka`ū.

The area was nominated to the National Register of Historic Places in 1974 :  these structures are not found anywhere else in Hawaii, and are associated with a unique event in human history and Volcano Island.

Footprints in the Desert of Ka`ū - photo USGS

Footprints in the Desert of Ka`ū - photo USGS

The geological evidence:

The volcanic ash and sand overlying the lava flows belong to the geological formation called Keanakāko`i Ash, in Hawaiian "The Falling sands", in an area near the Kilauea.

Initially connected to a one-time event dated 1790, it appears now that the formation started from the 1500s, with the last major event in 1790. The Keanakāko`i ashes are more correctly defined as layers of pyroclastic materials deposited between 1500 and 1790.
These ashes come from a time when the summit crater was very very deep, so that the level of its crater floor was below the level of the water table. Water leaked into the crater, where they formed a lake. The eruptions were of phreatomagmatic nature and the fragmentation of magma by the explosion was maximal. A pyroclastic surge swept everything at the over 150 km / h speed. covering the victims, likely died by suffocation in a hurricane of hot gas, and sulfur rather than because of falling ash. Accretionned apilli  found are an evidence of stormy conditions during eruptions.


The footprints are commonly called "fossilized", but they are not old enough to be real fossils. Fine dust turned to a tick mud under the rain during the eruption. Solidified under the tropical sun and preserved by an arid desert climate, they are held until today.



Footprints in the Desert of Ka`ū - these traces are fragile and should not be trampled - photo NPS / Volcanoes NP
Artist proof relating the assumption warriors killed by the pyroclastic surge in 1790 - Doc. NPS

Desert of Ka`ū : Blocks of lava expelled in an explosive series in 1924 covering the ash deposits of Keanakako`i issued between 1500 and 1790- the block on the bottom left is 50 cm. diameter - photo S.R.Brantley / 08.1998

Desert of Ka`ū : Blocks of lava expelled in an explosive series in 1924 covering the ash deposits of Keanakako`i issued between 1500 and 1790- the block on the bottom left is 50 cm. diameter - photo S.R.Brantley / 08.1998

Footprints in the Desert of Ka`ū - these traces are fragile and should not be trampled - photo NPS / Volcanoes NP

Footprints in the Desert of Ka`ū - these traces are fragile and should not be trampled - photo NPS / Volcanoes NP

Human history :


The footprints in the ashes were attributed initially to a part ofthe warrior in retreat after a battle, by Thomas Jaggar in 1921.
Recent studies attribute the footprints of human activities in the region during the 1500-1790's cycle of volcanic activity. Radiocarbon dating, and the discovery of many homes sites and roads are in line with an human occupation, including the harvest of chips for making tools. In 2008, it has been proven that most footprints belong to women and children, not adults men / warriors.

 

Sources :

- National Park Service  - Hawaii NP -  Keonehelelei - The Story of the Footprints Area - link

- Hawai`i Volcanoes National Park / Cultural Resources – Archeology / Keonehelelei -  “The Falling Sands” - link1 - link 2

- Pacific islands - link

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques

This week, from October 3 to 12, the Volcanoes National Park in Hawaii is celebrating ! Ceremonies and visits are planned during the week of the Hawaiian archeology.

Two sites are particularly emphasized, containing on one hand petroglyphs, secondly  fingerprints old over two hundred years.

 

 Pu'u Loa Petroglyphs - photo Love Big Island

Pu'u Loa Petroglyphs - photo Love Big Island

Pu'u Loa's Petroglyphs :

Pu'u Loa, meaning in Hawaiian "long hill" or "hill of long life," is a sacred place, located on the south flank of Kilauea volcano, which has more than 23,000 petroglyphs.

Hawaiians call this rock art "Ki'i pohaku" or stone image ... which corresponds to the Greek etymology of the name petroglyph, petros / petra or for stone, and glyphein for engraving.

They are mentioned for the first time in 1823 by the Reverend William Ellis, a missionary. They will be analyzed in 1914 by the anthropologist Martha Beckwith.

 

  Pu'u Loa Petroglyphs, anthropomorphic figures - photo Staecker

Pu'u Loa Petroglyphs, anthropomorphic figures - photo Staecker

  Pu'u Loa Petroglyphs, anthropomorphic figures - photo HVNP

Pu'u Loa Petroglyphs, anthropomorphic figures - photo HVNP

The center of Pu'u Loa is actually a volcanic dome surrounded by pahoehoe lava field, dated between 1200 and 1450.

Whatever the interpretation given to them, these petroglyphs have not only an aesthetic function, but also an esoteric function. They could be interpreted as the record of a journey around Hawaii, as an expression of the well-being and the human life, as a means of communication of past or current events, or as boundary marks or territories paths.

The patterns of the petroglyphs
consist mainly of units containing holes or wells. Other shapes are geometric, patterns in circles, or encrypted drawing, or represent the sails of canoes, headdresses sometimes with feathers, or anthropomorphic forms.

Wells are present in numbers: according to scientists, there placed the umbilical cord of newborns and then covered with a stone ... in order to ensure a long life for the child.

 

The trail to the Pu'u Loa Petroglyphs pass in the fields of pahoehoe lava. - Photograph by Christopher Elliott - Nat Geo

The trail to the Pu'u Loa Petroglyphs pass in the fields of pahoehoe lava. - Photograph by Christopher Elliott - Nat Geo

Pu'u Loa Petroglyphs - circles, aligned holes and other figures - photo National Park volcanoes of Hawaii

Pu'u Loa Petroglyphs - circles, aligned holes and other figures - photo National Park volcanoes of Hawaii

Other sites with petroglyphs can be visited on the Big Island: Waikola petroglyph preserve and Pukao petroglyph field.

The administration of the National Park protected petroglyphs building pontoons raised, and no longer using that modern breeding techniques, illustration and measures in direct response on the ground, minimizing contacts that could exacerbate the erosion phenomenon.

Tomorrow : the footprints of the Ka`ū desert.

 

Sources :

- Pacific islands parks - Hawai‘i Volcanoes National Park Events Celebrate Archeology & Hawaiian Culture - link

- National Park Services - Hawaii volcanoes / Pu'u Loa petroglyphs - link

- Love Big Ismand - the Pu' Loa petroglyphs - link

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
Nearly seven months after the unexplained disappearance of flight MH370 of Malaysia Airlines, new submarine research will be initiated in early October in the Indian Ocean where the aircraft would have crashed. The Boeing 777-200 of the Malaysian company disappeared March 8 shortly after taking off from Kuala Lumpur to Beijing. It was carrying 239 passengers and crew.


A reconstruction of  its probable trajectory to the falling into the sea was made following the "hooks" of communication systems by satellites. After an initial phase of research in March-April 2014, further research will be undertaken in early October.

Map of searches zone, past (in yellow) and future (grey) - posted by Geoscience Australia on 1/10/2014

Map of searches zone, past (in yellow) and future (grey) - posted by Geoscience Australia on 1/10/2014

The seabed were scanned over nearly 110,000 square kilometers from the study Chinese, Zhu Kezhzn and Australian Fugro Equator ships.

The Institute of Geoscience Australia has developed a 3D map from these bathymetric data, which reveals a rugged terrain around the Broken Ridge plateau, located west of the Australian continent.

These new structures are formed by seamounts, remnants of underwater volcanoes, ridges more than 300 meters high and a trench, deep more than 1,400 meters above the surrounding seafloor.

New seamounts discovered on Broken Ridge.

Broken Ridge is an oceanic plateau, located northeast of the southeast Indian Ridge, formerly attached to the oceanic plateau Kerguelen-Heard.

This plate consists of outpourings of basaltic lava, called LIP'S - Large igneous Province, produced by the Kerguelen plume. The lava is largely covered with mud sediments called foraminifera, consisting of dead plankton compacted due to the enormous pressure of the water column above them.

Location of Broken Ridge and the Kerguelen Plateau - cores drilled by ODP correlate to the map - one click to enlarge - doc. odp.tamu.eduLocation of Broken Ridge and the Kerguelen Plateau - cores drilled by ODP correlate to the map - one click to enlarge - doc. odp.tamu.edu

Location of Broken Ridge and the Kerguelen Plateau - cores drilled by ODP correlate to the map - one click to enlarge - doc. odp.tamu.edu

Separation of the oceanic plateaus Kerguelen from Broken Ridge / oceanic ridges in red :  West Indian ridge to the left,  Carlsberg to the center anf East Indian ridge to the right.

Separation of the oceanic plateaus Kerguelen from Broken Ridge / oceanic ridges in red : West Indian ridge to the left, Carlsberg to the center anf East Indian ridge to the right.

Although this is not the goal of this new research campaign, we expect that the data collected by the three ships involved will yield valuable information about this little explored area.

 

Sources:

- Australian government / Geoscience Autralia - Vol MH370 - cartes bathymétriques 3D - link

- L'express - Vol MH 370 : Trois navires entament de nouvelles recherches  - link

- Mantle sources and the highly variable role of continental lithosphere in basalt petrogenesis of the Kerguelen plateau and Broken ridge L.I.P. - by C.R. Neal, J.J. Mahoney and W.Chazey.

- L’Archipel de Kerguelen : les plus vieilles îles dans le plus jeune océan
par André Giret, Dominique Weis & al.

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques

According to media reports, including The Japan Times, Tha Japan News and CNN, the death toll from the eruption of Ontake September 27 continued to widen. Emergency services have just found 12 more bodies, bringing the death toll to 48.

Although the review of most of the victims is still ongoing, the official cause of death of the latter is recorded as "injury from direct impact by volcanic volcanic cinders (bombs) "
.

 2014.10.02 - Tokyo Fire Department rescue workers carry injured hikers down Mount Ontake on Sunday - picture Tokyo fire dept. / Japan News.

2014.10.02 - Tokyo Fire Department rescue workers carry injured hikers down Mount Ontake on Sunday - picture Tokyo fire dept. / Japan News.

It is noted that during the sudden eruption Saturday, hikers who managed to reach shelter in lodges near the top survived !

A survivor said: "I was busy taking a break, along with 18 other hikers near Lake Ninoike north side of the summit when the eruption occurred we rushed to a remote cottage of one. twenty meters. when the group reached the shelter, the rocks began to rain on the roof, and we saw numbers splashed in the lake Ninoike (impacts bombs) ...
“If we hadn’t had any place to escape, we could have been hit by the rocks and lost our lives. "

On Mount Ontake, there are 16 mountain huts and unnammed shelters, usually used as shelters during snow storms or bad weather ... but most are made of wood, unable to bear the weight of the ash in case of eruption. The lodge near the top saw its roof pierced by bombs and smashed windows, allowing the ashes to engulf.

No shelter in reinforced concrete exists on the Ontake volcano, and officials regret: "No injuries were criticized in previous eruptions, so we did not consider it necessary to build such shelters.
We’ve equipped mountain lodges with helmets and walkie-talkies [for use] in the event of a sudden eruption. However, it would have been possible to reduce injuries if there had been reinforced shelters and other facilities "(translated from an interview in the Japn News / The Yomiuri Shimbun)
 

Damage on the shelters of the summit of Ontake, by ash and rock fall (bombs) - photos Japan Times
Damage on the shelters of the summit of Ontake, by ash and rock fall (bombs) - photos Japan Times

Damage on the shelters of the summit of Ontake, by ash and rock fall (bombs) - photos Japan Times

The Japan News regrets the lack of such shelters on many Japanese volcanoes yet visited by many hikers and tourists.

Of the 47 volcanoes monotoring by the J.M.A., only twelve are equipped with anti-fallout shelter. Mount Fuji, which was attended by 280,000 hikers this summer, has no shelter of this type.

At Mount Aso, where three tourists were killed in 1979, 14 anti-fallout shelters are built close to the vent.

On the Asama, where eruptions occurred in 2004 and 2009, three semicircular arches are present within 500 meters of the crater, and another halfway. Together, they can accommodate a total of 300 people on sudden eruption.

 

Bunkers atop the Aso - photo Von Tasha

Bunkers atop the Aso - photo Von Tasha

Asama - shelters built at 500 m. of the crater - Courtesy of Komoro municipal government in Nagano Prefecture / The Japan News

Asama - shelters built at 500 m. of the crater - Courtesy of Komoro municipal government in Nagano Prefecture / The Japan News

Mr. Tadahide Ui, at the Crisis and Environment Management Policy Institute, says "Shelters built with consideration of the direction entrances face and other factors are useful in protecting people from cinders or ash deposits. In addition, it is important to make adequate preparations, such as equipping such facilities with helmets and other materials". It is also important to equip these shelters with helmets and survival equipment. Information on volcanic hazards should be expanded and distributed widely to nearby populations and hikers or other visitors.

 

Sources :

- The Japan News - Volcanoes nationwide lack livesaving shelters - link

- The Japan news - Raining rocks killed Mt.Ontake climbers - link

- Japan Times - Rescue teams suspend search on Mount Ontake as tremors worsen

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
 Mt. Rainier, the highest volcano in the Cascade Range - photo Walter Siegmund

Mt. Rainier, the highest volcano in the Cascade Range - photo Walter Siegmund

Mount Rainier, the highest point of the volcanic Cascade Range, is a stratovolcano which rises to 4,392 meters. Its current vertex is wearing two partially overlapping craters.

The Global Volcanism Program describes an extensive active hydrothermal system, which causes periodic melting glaciers covering its sides and place, in the summit ice cap, an elaborate network of ice caves. Hydrothermal alteration of the upper parts of the volcano contributes to its structural weakness.

 

The ice caves of Mt Rainier, a volcano in the Cascade Range.
Summit Ice caves of Mt Rainier - Doc. Seattle Times / Mark Rowlin

Summit Ice caves of Mt Rainier - Doc. Seattle Times / Mark Rowlin

The first description of the caves apical is made in 1870 by H.Stevens and Ph.Van Trump. "At dusk, we were delighted by jets of vapor amount rocky edge. Heat had dug an opening in the snow " . They settled in for the night ..." and spent a miserable night, frozen on one side, and in a bath of sulphurous fumes of the other. "

Twin brothers Whittaker ventured into the caves in 1954, but quickly made a U-turn for fear of toxic fumes.

Lou Whittaker returned in 1970 with a respirator used by firefighters, crawling "through the eye of the needle", a small opening on the south side of the crater. For several decades, the Whittakers guided visitors through the caves under the Paradise Glacier ... but describe the apical caves as "dark and smoky, with a hint of sulfur, but with a breathable air."

In the 70s, during an expedition called Project Crater, Lokey and a team of young climbers and scientists camped for weeks at the top, where they found the remains of the expedition of the 19th century.

Mt Rainier - Zoe Harrold, specialist microbes in extreme environments, takes water samples from the lake recently discovered - photo Francois-Xavier De Ruydts / Special to The Seattle Times - more great photos on the site references.

Mt Rainier - Zoe Harrold, specialist microbes in extreme environments, takes water samples from the lake recently discovered - photo Francois-Xavier De Ruydts / Special to The Seattle Times - more great photos on the site references.

The Seattle Times reports the expedition of 2004, by Lokey and his team, this time equipped with modern means of survival and monitoring.

A storm will force a part of the team to enter the nearest summit cave ... the air is heated to 40 ° C by the fumarole
but harmful gases not detected, and they set up camp. A map is established by means of lasers and inclinometers, and a lake is discovered, not yet listed ... he was named Lake Adélie because the azure water reminds to Eddy Cartaya the blue eyes of the penguin of the same name. A team member shows signs of pulmonary edema and the expedition should be discontinued. At the size and complexity of the passages, another mapping expedition is planned for 2015.

Lokey's group, on its side, is sampling gas, particularly the helium contents, missing data for Rainier, and could indicate possible magma movements.Samples taken from lake water taken, from surrounding mud, and ice are also performed.

Interesting benefits are expected from samples examinations, the combination of heat and volcanic gas, cold water and frozen ground would be similar to the conditions for the emergence of life on Earth.

 

Stack of lenticular clouds on Mt.Rainier - National Geographic Photo / Arco images.

Stack of lenticular clouds on Mt.Rainier - National Geographic Photo / Arco images.

Sources :

 - The Seattle Times- Under Rainier’s crater, a natural laboratory like no other - link

 - Science direct - Fumaroles in ice caves on the summit of Mount Rainier—preliminary stable isotope, gas, and geochemical studies – by D.R. Zimbelman, R.O. Rye, G.P. Landis. - link 1 - link 2

- USGS - Living with an active volcano in your backyard - An educator guide with emphasis on Mt. Rainier.

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
 The "mud volcanoes" - photo MeteoWeb

The "mud volcanoes" - photo MeteoWeb

The tragic deaths of two children occurred during a visit to the Parco del Maccalube near Agrigento in Sicily on September 27, reminds us that mud volcanoes are dangerous, although secondary phenomena facing the risk generated by volcanic eruptions.

Maccalube di Aragona - the emergency services mobilized by the incident of 27.09.2014 - photo MeteoWeb

Maccalube di Aragona - the emergency services mobilized by the incident of 27.09.2014 - photo MeteoWeb

General view of the area Maccalube di Aragona - Doc. Google 2014

General view of the area Maccalube di Aragona - Doc. Google 2014

An article by the INGV - Palermo explains the phenomenon of formation of mud volcanoes, resulting in intermittent gas emissions, water and sediments.

Sedimentary volcanism is a typical geological phenomenon of sedimentary basins, characterized by compressive tectonics, expressed in surface by mud volcanoes.

In central and western Sicily, especially in Caltanissetta and Aragona, we notice a  degassing of mantle fluids, despite the absence of a near volcanic system.

In recent years, an intense and sudden explosive activity is characterized by the emission of large amounts of mud. Researchers have demonstrated a correlation between the explosive activity and seismic activity at the local level, requiring further interdisciplinary studies (in the fields of structural geology, geochemistry, seismology).

 

Maccalube di Aragona - "Vulcanelli" - photo ASSI / via Geovol

Maccalube di Aragona - "Vulcanelli" - photo ASSI / via Geovol

The mechanism governing the sedimentary volcanism is related to periodic lifts of gases, including methane, and water to the surface. During the percolation, the fluids encounter argillaceous levels, which tend to liquefy and to come out with gas and water. The clay layers may be temporary an "impermeable cap" , that will suddenly give way under gradually increasing pressure, leading to an explosion, accompanied by a column of liquid and gas up to 10-25 meters high.

 
In Maccalube di Aragona, the outputs of mud can be done simply at centimeter cracks, or occur in basins metric size, or form small mud cones concentrated on a small hill ... hence their dénominantion "Vulcanelli" / small volcanoes.

Volumes issued mud can reach thousand cubic meters.

The final paroxystic event was held on May 5, 2012, around 2am, where the Maccalube hill was brutally transformed by the explosion of mud mixed with gas and salt water, which destroyed the present cones. On several occasions, these paroxistic events are accompanied by inflammation of the gas, giving fiery fountains fed continuously by the flow of gas emitted during paroxysms.

Evolution of Maccalube di Aragona between 2003 and 2013 - Image credit Franco Ortolani (www.geologi.it) / MeteoWeb

Evolution of Maccalube di Aragona between 2003 and 2013 - Image credit Franco Ortolani (www.geologi.it) / MeteoWeb

Sources :

- Meteoweb - Tragica eruzione di fango in Sicilia: era già successo negli anni scorsi, ecco le prove - link

- INGV News – Il vulcanismo sedimentari della Maccalube - link / http://193.206.213.9/intranet/gest_news/uploads/4250Articolo_Macalube_rivisto_con_figure.pdf

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