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  Moderator vrijdag 1 maart 2019 @ 11:27:28 #1
8781 crew  Frutsel
pi_185316902
registreer om deze reclame te verbergen
fuego-volcano.jpg


Overal in de wereld kom je vulkanen tegen. Onder water, in bergruggen of onder gletsjers. Ook zijn er vulkanen waar niemand het bestaan nog van weet of waar we pas sinds kort achter kwamen dat het daadwerkelijk een vulkaan is.

In dit topic kun je alle informatie kwijt over vulkanen, je kunt vragen stellen over vulkanen of uitbarstingen maar vooral kun je hier op de hoogte blijven van de recentelijke ontwikkelingen van vulkanen overal ter wereld.

Voel je vrij om mee te posten. Zie je ergens een interessant artikel, heb je een nieuwsbericht, post het hier en doe gezellig mee :)

Wat is een vulkaan

Waar bevinden zich de vulkanen dan?
De meeste vulkanen bevinden zich rondom de tektonische platen van onze planeet. Daar waar de aardplaten langs of onder elkaar schuiven vinden aardbevingen plaats of is er vulkanische activiteit.

Een uitzondering op deze regel zijn de zogenaamde 'hot-spots'. Dit zijn plaatsen op aarde waarbij magma uit de aardmantel door de aardkorst naar boven komt. Voorbeelden hiervan zijn de eilanden van Hawaii en de Canarische Eilanden groep. Maar er zijn er meer.

De meeste vulkanen liggen rondom de zogenaamde 'Ring of Fire'.

De zogenaamde Ring van Vuur is een bijna ringvormige keten aan vulkanisch actieve gebieden. Deze Ring "verbindt" zo de Zuidelijke Pacifische Oceaan nabij Nieuw_Zeeland met de klok mee over Kamtsjatka en Alaska tot aan zuid-Chili.

Ring van Vuur
ringfire.gif


Soorten vulkanen
Er zijn 6 verschillende soorten vulkanen.

De spleetvulkaan
Een lange scheur in de aardkorst waardoor magma naar buiten komt. Deze ontstaat als twee tektonische platen uit elkaar drijven. Je vindt deze vooral bij oceaanruggen.

De schildvulkaan
Dit is een brede, ondiepe vulkaankegel, die ontstaat doordat het lava dat eruit stroomt, dun en heet is en heel langzaam afkoelt.

De koepelvulkaan
Deze kent een steile, bolle helling die gevormd is door dikke snel afkoelende lava.

De slakkenkegel
Een vulkaan die naast lava ook veel as uitspuugt. De berg die door deze vulkaan gevormd wordt, is dan ook opgebouwd uit lagen as en lava die elkaar afwisselen.

De samengestelde vulkaan
Deze is net zo opgebouwd als de slakkenkegel maar heeft naast de hoofdkrater nog meerdere kleinere kraters op haar flanken.

De calderavulkaan
Dit is een oudere vulkaan met aan de bovenkant een grote brede krater. In deze krater hebben zich weer kleinere nieuwe kraters gevormd.

Hotspots
Doordat een zeer hete brandhaard (hot-spot) in de mantel, door de aardkorst heen brandt.

Overige vormen
Andere vormen van vulkanisme zijn de geisers en de hete bronnen. Die vind je vaak in de buurt van vulkanen waar de aardkorst dunner is en de warmte van het magma verder doordringt in de aardkorst. Een geiser is een holte in de aardkorst of een waterhoudende grondlaag, die door het onderliggende magma wordt verwarmd tot het kookpunt. Het water kan dan tot 500 meter in de lucht spuiten. Een hete bron werkt op dezelfde manier alleen wordt het water daar niet zo verhit, dat het onder druk van stoom eruit spuit.

Supervulkanen
Naast de 'reguliere' vulkanen hebben we op aarde ook 'supervulkanen'. Dat zijn vulkanen die in staat zijn om tot catastrofale uitbarstingen te komen die het leven op de hele planeet kunnen be飊vloeden. Zij kunnen bijvoorbeeld een nieuwe ijstijd in gang zetten. De laatste uitbarsting van een supervulkaan was die van Toba (Sumatra) zo'n 74.000 jaar geleden. De bekendste supervulkaan is vermoedelijk Yellowstone Park in de Verenigde Staten. De dichtstbijzijnde supervulkaan is de Campi Flegrei bij Napels

Heeft Nederland een vulkaan?
Jazeker! De naam ervan is Zuidwalvulkaan, en ligt 17 km ten westen van Harlingen
maar ... die is letterlijk allang dood en begraven. Deze ligt namelijk vele honderden meters onder de bodem van de huidige Waddenzee. De vulkaan was actief in het Laat-Jura, zo'n 152 miljoen jaar geleden.

Maar slapen vulkanen echt en zijn ze echt dood? Daar verschillen wetenschappers van mening over. Langere tijd werd ook gedacht dat bijvoorbeeld de supervulkaan in de Eifel dood en begraven was maar recente studies hebben uitgewezen dat deze zeker niet dood is. Sterker nog: Onlangs werd bekend dat de magmakamer van de Laacher See vulkaan zich weer langzaam aan het vullen is.

Actueel Actieve vulkanen
active-volcano-map.jpg
Met dank aan Volcano Discovery


Belangrijke Links
Status vulkanen Indonesie
Volcano webcams all over the world
BBC-How volcanoes work
Smithsonian / USGS Weekly Volcanic Activity Report
Volcano Discovery
Live Science - Volcanoes
vulkaan.startpagina.nl


Foto's
2018: The volcanic year in pictures

Actuele vulkaantopics in WKN
Aardbevingen en uitbarsting Etna
Uitbarstingen op Hawaii - Kilauea
Aardbevingszwerm bij Santorini
Centrale topic over de IJslandse vulkanen
Activiteit bij Mayotte neemt toe
Honderden doden bij uitbarsting Krakatau
Campi Flegrei - Supervulkaan bij Napels

Archief en Verzameltopics
Reeks: Vulkanen op Fok!
Krakatoa
Etna
Supervulkaan Yellowstone
Uitbarsting Merapi 2010
Mount St.Helens
Uitbarsting El Hierro Canarische Eilanden
Vulkaanuitbarsting Chili
Tungaruhua Ecuador
Vulkanen op IJsland

Interessante Twitter-accounts van Vulkanologen
https://twitter.com/johnseach
https://twitter.com/volcanologist
https://twitter.com/janinekrippner
https://twitter.com/kenhrubin
  Moderator vrijdag 1 maart 2019 @ 11:33:00 #2
8781 crew  Frutsel
pi_185316992
quote:
These ice-covered Chilean volcanoes could erupt soon

Stretching over 4,350 miles (7,000 km) across seven countries, the Andes are the world’s longest mountain range. They make up the southeastern portion of the Ring of Fire and are well-known for their abundant volcanoes.

The Chilean Andes are home to 90 active volcanoes, all monitored by the Chilean National Geology and Mining Service (Sernageomin). The agency categorizes volcanic activity using four distinct alert levels: green (normal level of activity), yellow (increased level of activity), orange (probable development of an eruption in the short term), and red (eruption is ongoing or imminent). Increased volcanic activity is associated with frequent earthquakes; plumes of gas, rocks, or ash; and lava flows.

Two areas monitored by Sernageomin are currently showing signs of increased activity: the Nevados de Chill醤 and Planch髇-Peteroa volcanic complexes. The agency issued orange and yellow alert levels for them, respectively.

Nevados de Chill醤 Volcanoes: Orange Alert

The Nevados de Chill醤 volcano complex is composed of several glacier-covered volcanic peaks. When these volcanoes erupt, the glacial ice sitting atop them melts and mixes with lava, which can result in dangerous lahars, or mudflows. Several small earthquakes and the formation of new gas vents led Sernageomin to issue a yellow alert on December 31, 2015.

On April 5, 2018, Sernageomin upgraded the Nevados de Chill醤’s yellow alert to an orange alert, following thousands of tremors and a thick, white column of smoke rising from the area. This signaled the likelihood of an eruption in the near future.

Sernageomin’s most recent volcanic activity report for Nevados de Chill醤, issued on February 11, 2019, cited persistent seismic activity, which is directly related to increased frequency of explosions, along with the growth and/or destruction of the lava dome that lies in the crater. The expected eruption is most likely to have moderate to low explosive power, but sporadic observations over the last year have shown higher-than-average energy levels.

On February 15, 2019, the Volcanic Ash Advisory Center in Buenos Aires documented a volcanic-ash plume reaching 12,139 feet (3,700 meters) high at Nevados de Chill醤, an example of the above mentioned “higher than average energy levels.”

Bottom line: Recent increased volcanic activity in the Nevados de Chill醤 prompted Chilean authorities to issue an orange alert in anticipation of an eruption.
  Moderator / Redactie Sport / Weblog vrijdag 1 maart 2019 @ 13:33:17 #3
17650 crew  rubbereend
JUICHEN
pi_185319059
_O_ voor deze reeks
DeLuna vindt me dik ;(
Op zondag 22 juni 2014 12:30 schreef 3rdRock het volgende:
pas als jullie gaan trouwen. nu ben je gewoon die Oom Rubber die met onze mama leuke dingen doet :)
  Moderator woensdag 20 maart 2019 @ 11:53:16 #4
8781 crew  Frutsel
pi_185734613
registreer om deze reclame te verbergen
quote:
Explosion at Mexico's Popocatepetl volcano hurls hot rock, ash

MEXICO CITY -- An explosion at the crater of Mexico's Popocatepetl stratovolcano has hurled incandescent rock about 1 1/2 mile down its slopes and sent ash into the night sky near the nation's capital.

The Mexican government disaster agency says ash was expected to fall on towns near the crater following the outburst at 9:38 p.m. Monday.

The 17,797-foot volcano has been particularly active in recent months, several times spewing out sprays of hot rock and towering clouds of ash

Some 25 million people live within about 60 miles of the mountain's crater.

pi_185908558
nrc twitterde op donderdag 28-03-2019 om 18:45:08 Inwoners van omliggende dorpen bij de #Popocat閜etl in #Mexico zijn gewaarschuwd: de #vulkaan spuwt as en rook.https://t.co/9Zp4n3kbQY reageer retweet
  Moderator vrijdag 29 maart 2019 @ 08:36:03 #6
8781 crew  Frutsel
  Moderator maandag 1 april 2019 @ 09:48:46 #7
8781 crew  Frutsel
pi_185965604
registreer om deze reclame te verbergen
quote:
Increased activity at Taal volcano, alert level raised, Philippines

The Philippine Institute of Volcanology and Seismology has raised the alert status of Taal volcano from Alert Level 0 to Alert Level 1 (abnormal) on March 28, 2019. The last eruption of this volcano took place in 1977. Powerful pyroclastic flows and surges from historical eruptions have caused many fatalities.

There has been a recent change in the condition of Taal Volcano based on the following observed changes in monitoring parameters:

Volcanic Earthquake Activity: A total of 50 volcanic earthquakes have been recorded by Taal Volcano’s seismic monitoring network since March 22, 2019. This recent earthquake swarm may indicate rock-fracturing beneath the edifice possibly associated with hydrothermal activity. Prior to this, the frequency of volcanic earthquakes was on average within the baseline levels (0-5 events/day) since 2016.
Ground Deformation: Cumulative elevation changes of the volcanic edifice based on precise leveling (PL) measurements this March 2019 indicate that it has slightly inflated relative to November 2018 after a period of general deflation since 2016. Slight inflation of the edifice starting in January 2019 was also recorded by continuous Global Positioning Systems (GPS) after a period of general deflation since 2016.
Gas Emission: Dissolved carbon dioxide (CO2) concentrations in Taal Main Crater Lake (MCL) based on continuous measurements have been gradually increasing since February 2019, indicating a slight increase in the input of volcanic CO2 degassing from the hydrothermal system into the lake.
In view of the above, DOST-PHIVOLCS has raised the alert status of Taal from Alert Level 0 to Alert Level 1. This means that the volcano is at an abnormal condition.

The public is reminded that the Main Crater should be strictly off-limits because sudden steam explosions can occur and high concentrations of lethal volcanic gases can be released.

The northern portion of the Main Crater rim, in the vicinity of Daang Kastila Trail, can also become hazardous when fumarolic or degassing activity along existing fissures suddenly increases.

Furthermore, the public is also reminded that the entire Volcano Island is a Permanent Danger Zone (PDZ), and permanent settlement in the island is strongly not recommended.

Taal Volcano’s seismic monitoring network recorded 3 volcanic earthquakes during the past 24 hours, PHIVOLCS reported 00:00 UTC (08:00 LT), March 29.

Field measurements on March 28, 2019 at the eastern sector of the Main Crater Lake yielded an increase in water temperature from 30.7 癈 to 31.7 癈 (87.2 - 89 癋), a decrease in water level from 0.46 m to 0.41 m (1.5 to 1.3 feet) and increase in acidity from pH 2.95 to pH 2.67.

Ground deformation measurements through precise leveling surveys from March 18 to 27, 2019 indicated slight inflation of the edifice consistent with recent results from continuous GPS data.
  Moderator woensdag 10 april 2019 @ 21:26:27 #8
8781 crew  Frutsel
pi_186145390
quote:
Increased seismicity and temperature at Te Wai ā-moe, Mount Ruapehu, New Zealand
GNS Science volcanologists are reporting another phase of high lake temperatures at Te Wai ā-moe (Crater Lake), Mount Ruapehu along with moderate levels of volcanic tremor. The Volcanic Alert Level remains at 1.

GeoNet is continuously recording the temperature of Te Wai ā-moe since 2009. Over this time, the temperature has often cycled between ~ 15 and 45 癈 (59 - 113 癋) over a period of about 12 months.

However, in September 2018 they recorded a departure from this, and for the following 6 months the lake temperature remained elevated (at ~ 30 癈 / 86 癋).

Over the last two weeks, the lake temperature has risen further, at a rate of around 0.5 癈 (0.9 癋) per day, to 42 癈 (107.6 癋) on April 9. To put this in context, only 1% of post-2009 temperatures have exceeded 42 癈 and a similar temperature last occurred in May 2016.

The level of volcanic tremor typically also increases when the lake temperature rises, and this has been the case in the last 2 weeks. The current tremor intensity is moderate. In previous heating cycles, this increased tremor lasted for a few days to several weeks.

In the past, eruptions at Ruapehu have occurred more often when the lake exceeded 45 癈 (113 癋). However, a temperature of 46 癈 (114.8 癋) was recorded in 2016 with no eruption.

While Volcanic Alert Level remains at one, which is a minor unrest, 'it is a useful reminder that eruptions can occur with little or no warning,' Duty Volcanologist Agnes Mazot said. GNS Science continues to closely monitor Mt Ruapehu and the country's other active volcanoes.

The last eruption of this volcano took place on September 25, 2007 - Volcanic Explosivity Index of 3. Its last major eruptive phase started on June 16, 1996, and lasted until September 1 of the same year (VEI 3).
pi_186161476
Een mooi animatiefilmpje over de uitbarsting van Anak Krakatoa en de daarop volgende tsunami van 22 december j.l.
Bij Hoevelaken linksaf
  Moderator donderdag 18 april 2019 @ 11:26:37 #10
8781 crew  Frutsel
pi_186291099
quote:
Increased seismicity and ground-deformation at Mauna Loa Hawaii
Activity at Hawaiian Mauna Loa volcano has risen to levels comparable to a higher period of activity between 2014 and 2017, HVO scientists said. The last eruption at the volcano took place in 1984.

While there is no cause for alarm, those signs of higher activity include increased earthquakes and ground deformation around the volcano's summit, HVO scientist-in-charge Tina Neal said, as reported by the Hawaiian Tribune-Herald.

The volcano has experienced up to 90 earthquakes a week since August, although most of the quakes have been mild, measuring 2.0 or less on the Richter scale, she said, adding that earthquakes on Mauna Loa dropped to less than five a week around early 2018.

Deformation rates appear similar to how they were in the volcano's more active period starting in 2014, but are not as high as the highest deformation during that time, when some parts of the volcano measured approximately 5 cm (1.9 inches) in a year.

The increased activity comes shortly after the cessation of significant volcanic activity at Kilauea whose eruption last year also began shortly after a decrease in activity at Mauna Loa.

While there is some geological basis to suggest a correlative pattern, this new activity will test the hypothesis.

"An eruption could be anywhere from months to years away," Neal said. "But we do know that it’s not days or weeks away."

Mauna Loa has not erupted with the frequency of Kilauea in recent years, but its 33 historical eruptions have, on average, generated much larger volumes of lava on a daily basis. Lava flows on Mauna Loa tend to travel much longer distances in a shorter period of time than those on Kilauea. Thus, warnings and notifications in the first few hours of an eruption are critical for public security.
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