Sunday, September 28, 2014

Volcanoes in the News: From Bardarbunga to Ontakesan

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Ontakesan Volcano

There are so many active volcanoes around the world right now it is hard to keep track of them.

Yesterday, Mt. Ontakesan in Japan blew up without warning, and it has been a tragedy for hikers and climbers who were on the mountain. Searchers have rushed to the area to try and rescue people in the area, now covered in volcanic ash. But the volcano remains dangerous and is still erupting. I hope they find some survivors, but it's a grim situation.

Ontakesan Live Webcam

The past few months, I've become addicted to the Iceland livecam for Bardarbunga, a significant volcano that is close enough to Europe to really cause trouble if it were to blow up suddenly. Bardarbunga is still significant for it's immense cloud of deadly sulfur dioxide that is already causing health concerns there in Iceland. And the Holuhraun lava field is growing by leaps and bounds. At night you can see the hot lava glowing as it streams away towards the sea. The main caldera of Bardarbunga seems to be sinking with every earthquake, and at night glows like the Eye of Sauron from Tolkien's tales - inspired by the old Icelandic sagas.

Bardarbunga Cam 1
Bardarbunga Cam 2

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This video shows a volcano called Mt. Tavurvur that recently exploded in Papua New Guinea. Brace yourself for the boom! You can almost see the sound wave, and certainly can see the large boulders hitting the water. The people who caught this on camera were lucky not to be closer.

A report came out this weekend that Mt. Saint Helens in Washington State is possibly coming back to life. In fact, scientists don't really know why it ever stopped erupting.

From King5 News
Geologists were surprised that the mountain stopped erupting in 1986. "Many of us were expecting it to continue a while," said USGS seismologist Seth Moran.

The second lava dome, which started appearing in 2004, appeared at a different spot in the crater. Lava that appeared from 2004-08 was much more solid than during the earlier phase.

Even though the lava dome hasn't erupted since 2008, its shape still is changing.

"As it cools, it fractures and settles and falls apart," said Dan Dzurisin, a USGS geologist. Rockfall has also been changing the shape of the crater rim.

And 5 miles below the volcano, there are signs that the magma chamber that fueled both eruptions is recharging. Dzurisin said the USGS is focusing on the rate of recharging and whether the magma can compress in the chamber, rather than flowing toward an outlet to the earth's surface.
Mt. Saint Helens in Washington
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Then there was an earthquake swarm this weekend under Mammoth Lakes, an ancient dormant volcano near the California/Nevada border. The USGS put out a warning that the movement had volcanic traits, while other experts believe it is merely shaking due to pressure from hot springs. (Of course hot springs go along with volcanoes, so....)

From UPI
The quakes struck the region between 9 a.m. Thursday and 1:49 a.m. Friday.
The USGS said it's because Mammoth Mountain, a lava-dome complex, lies along the rim of the Long Valley Caldera.
"Recent volcanic unrest, including seismicity, gas emission, and tree kill, is thought to be related to a dike intrusion beneath Mammoth Mountain in 1989," the USGS website said. "Both Long Valley Caldera and Mammoth Mountain have experienced episodes of heightened unrest over the last few decades (earthquakes, ground uplift, and/or volcanic gas emissions). As a result, the USGS manages a dense array of field sensors providing the real-time data needed to track unrest and assess hazards."

LA Times
The earthquakes may have been triggered by water pressure from area hot springs shifting through the ground surface, stressing tectonic plates. Scientists, Shelly said, are closely watching the earthquake swarm, but don’t believe it's connected to any magmatic activity.
Shelly said seismic analysts plan to review the swarm and update locations and magnitudes of the quakes, but the activity is not nearly on the size and scale of what was measured in the 1980s and 1990s.
. . . The Long Valley caldera is one of the most seismically active regions in the state, and is part of a quiet network of 17 volcanoes throughout California. Many of the older volcanoes haven't been active for thousands of years.
The last time the Long Valley caldera erupted was 50,000 years ago.

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