Fuego volcano (Guatemala): increasing lava flows
At the same time, explosive activity at the summit crater remained at low to moderate levels, with strombolian explosions that produce ash plumes of up to 800 m height and incandescent jets visible from distance. Some of the explosions generate shock waves that can be felt and heard in up to 15 km distance, causing roofs, doors and windows of houses to rattle.
Fine ash fall occurred in Panimaché, Morelia abd Sangre de Cristo.
http://www.volcanodiscovery.com/fuego/news/38911/Fuego-volcano-Guatemala-increasing-lava-flows.html
Two volcanoes erupt in Indonesia
Posted by Saravanan Jawahar on November 19, 2013
Jakarta, Nov 19 (TruthDive): Mount Sinabung and Mount Merapi, the active volcanoes in Indonesia erupted Monday, officials said.
The 2,911-metre high Mount Merapi, the most active volcano in Indonesia, located in Yogyakarta province, part of central Java, emitted volcanic material and thick smoke on Monday morning at around 04:52 a.m. local time, which enforced hundreds of residents from three nearby villages to flee. The mountain ejected a cloud of black ash about 2,000 metres high, officials said. Authorities have asked travellers and tourists to stay away from the volcano.
Mount Merapi's most violent eruption was in 2010, which killed about 350 people and displaced thousands of others. Sutopo Purwo Nugroho, chief of the National Disaster Mitigation Agency said the eruption, which was triggered by small earthquakes, prompted around 600 families to rush to evacuation posts but they were returning home as there was no imminent threat.
Meantime, the 2,475-metre-high Mount Sinabung, located in North Sumatra province, also erupted on Monday morning, shooting a column of ash about 8,000 metres high. Agus Budianto, the head of volcano observation at the country's volcanology agency said this eruption is the biggest since the volcano first rumbled back to life in September after being dormant for three years.
Ministry spokesman Bambang Ervan said in a statement that the transport ministry was redirecting flights away from a certain path because of Mount Sinabung's latest eruption.
Budianto said the ash with volcanic material emitted towards the southwest direction. Indonesian transport ministry spokesman Bambang Ervan said the volcanic ash was found to have shot up to 25,000 metres in the air that would endanger flights. Over 6,000 people have been displaced since the beginning of this month as Mount Sinabung erupted occasionally.
Indonesia, a vast archipelago with 17,500 islands has 129 active volcanoes and connects major tectonic fault lines known as the "Ring of Fire" between the Pacific and Indian oceans.
http://truthdive.com/2013/11/19/two-volcanoes-erupt-in-indonesia-2.html~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
http://englishrussia.com/2013/11/19/the-live-volcano-of-kamchatka/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Why Does Italy's Mount Etna Keep Erupting?
 |
| A spectacular eruption at Italy's Mount Etna on the night of March 5, 2013. A lenticular cloud is passing in front of the fountaining lava. Credit: Boris Behncke/© INGV - National Institute of Geophysics and Volcanology |
Another evening, another eerie glow atop Italy's Mount Etna. The eruptions rocketing from volcanic craters atop Etna's summit suffuse dark nights with a fiery aura as lava jets into the air.
The volcano erupted again this past weekend, tossing lava bombs that looked like fireworks from afar. The blast from Etna's New Southeast Crater is the latest in a string of spectacular eruptions.
Mount's Etna's busy pace produces enough lava each year to fill Chicago's Willis Tower (the former Sears Tower), a 2012 study found. Whether it's a few fast-flowing lava flows or a fiery fountain, the volcano's outbursts have been a constant companion for Sicilians for more than 2,000 years.
Yet geoscientists are still trying to figure out why Etna erupts so frequently, and in so many different ways. Nearly every kind of eruption has appeared at Etna over the millennia — quiet lava streams, sputtering fire fountains and even deadly pyroclastic flows, the superheated mix of ash, lava fragments and gases that race down steep volcanic slopes.
The working explanation boils down to indigestion: how volcanic gases build up inside Etna's underground plumbing.
Tiny bubbles
As with all volcanoes, the magma inside Etna holds gas bubbles, such as carbon dioxide, sulfur dioxide and water.
Etna is one of the gassiest volcanoes on Earth, pumping out more carbon dioxide than any other volcano, said Keith Putirka, an igneous petrologist at California State University, Fresno, who has studied Etna's deep magma system.
"Even though Etna isn't a massive volcano, it puts out massive amounts of carbon dioxide," Putirka told LiveScience's OurAmazingPlanet. "If you threw several more Mount Etnas onto the planet, you could really drive climate change in a serious way."
Scientists think that when magma deep below a volcano rises toward the surface, the difference between speedy or slow ascents can influence the type of eruption. When magma moves quickly, gas stays trapped in the molten rock and explodes when it's suddenly released at a volcanic vent, similar to opening a fizzy-drink bottle. But slowly traveling magma has time to lose its bubbles, leading to lots of lava but little to no explosions.
Magma viscosity (a fluid's resistance to flow) also plays a role in how Etna and other volcanoes erupt, Putirka said. Thick, sticky magma can hold on to gas bubbles longer than low-viscosity magma, such as the basalt now erupting at Etna and other volcanoes such as Hawaii's Kilauea.
The first recorded Etna eruption dates back to 1,500 B.C., but the volcano is much older, with the first lava flows pouring out 500,000 years ago. Thanks to geologic detective work, such as dating older lava flows, scientists know the volcano has had times of sleep. But a simple observation helps, too.
"There must have been periods when the volcano shut down, because otherwise, it would be a lot taller," Putirka said. "There has been a really detailed work to understand the stratigraphy, and careful age dating, to sort that out."
An outlier
Etna's location is another geologic mystery. One of the world's largest continental volcanoes, rising more than 10,900 feet (3,330 meters), Etna sits near the collision of two tectonic plates — near, but not on top of, the collision zone. Etna's unusual location has confounded scientists for decades.
Unless they're sitting on top of hot spots — plumes of superheated rock rising from deep in Earth's mantle — most volcanoes on Earth occur where tectonic plates move apart or crash together, with one plate sliding down under the other (called a subduction zone). In the Mediterranean, the African plate is bashing into Europe, and part of it is descending beneath the eastern Mediterranean Sea.
Etna is too far from its local subduction zone to explain the volcano's magmatism, most researchers agree, though small fragments of crust caught up in the plate boundary near Etna make the collision zone complex.
But thanks to recent, detailed looks at the deep structure of the collision zone, scientists now think the African crust sinking near Etna tore, letting hot rock escape and punch through the crust underneath Sicily.
"What they're seeing in the geophysics is a huge tear in the slab," Putirka said. "That sets up a convection current in the mantle that drives volcanism further inland."
Etna's value as a natural volcanic laboratory earned the peak a World Heritage Site designation this past June. Yet even after being observed constantly for more than 2,000 years, the mountain still holds many mysteries, Putirka said.
"At a fundamental level, there's a lot we still don't understand in terms of eruptions," Putirka said.
http://www.livescience.com/41368-why-mount-etna-erupts.html--
__._,_.___
No comments:
Post a Comment