On the shoulder of a giant: Precursor volcano to the island of O'ahu discovered
21 hours ago
Researchers from the University of Hawai'i – Mānoa (UHM), Laboratoire des Sciences du Climat et de L'Environment (France), and Monterey Bay Aquarium Research Institute recently discovered that O'ahu actually consists of three major Hawaiian shield volcanoes, not two, as previously thought. The island of O'ahu, as we know it today, is the remnants of two volcanoes, Wai'anae and Ko'olau. But extending almost 100 km WNW from Ka'ena Point, the western tip of the island of O'ahu, is a large region of shallow bathymetry, called the submarine Ka'ena Ridge. It is that region that has now been recognized to represent a precursor volcano to the island of O'ahu, and on whose flanks the Wai'anae and Ko'olau Volcanoes later formed.
Prior to the recognition of Ka'ena Volcano, Wai'anae Volcano was assumed to have been exceptionally large and to have formed an unusually large distance from its next oldest neighbor - Kaua'i. "Both of these assumptions can now be revised: Wai'anae is not as large as previously thought and Ka'ena Volcano formed in the region between Kauai and Wai'anae," noted John Sinton, lead author of the study and Emeritus Professor of Geology and Geophysics at the UHM School of Ocean and Earth Science and Technology (SOEST).
In 2010 scientists documented enigmatic chemistry of some unusual lavas of Wai'anae. "We previously knew that they formed by partial melting of the crust beneath Wai'anae, but we didn't understand why they have the isotopic composition that they do," said Sinton" Now, we realize that the deep crust that melted under Waianae is actually part of the earlier Ka'ena Volcano."
This new understanding has been a long time in the making. Among the most important developments was the acquisition of high-quality bathymetric data of the seafloor in the region. This mapping was greatly accelerated after UH acquired the Research Vessel Kilo Moana, equipped with a high-resolution mapping system. The new data showed that Ka'ena Ridge had an unusual morphology, unlike that of submarine rift zone extensions of on-land volcanoes. Researchers then began collecting samples from Ka'ena and Wai'alu submarine Ridges. The geochemical and age data, along with geological observations and geophysical data confirmed that Ka'ena was not part of Waianae, but rather was an earlier volcanic edifice; Wai'anae must have been built on the flanks of Ka'ena.
"What is particularly interesting is that Ka'ena appears to have had an unusually prolonged history as a submarine volcano, only breaching the ocean surface very late in its history," said Sinton. Much of our knowledge of Hawaiian volcanoes is based on those that rise high above sea level, and almost all of those formed on the flanks of earlier ones. Ka'ena represents a chance to study a Hawaiian volcano that formed in isolation on the deep ocean floor.
Despite four different cruises and nearly 100 rock samples from Ka'ena, researchers say they have only begun to observe and sample this massive volcanic edifice. While this article was in press, SOEST scientists visited Ka'ena Ridge again – this time with the UH's newest remotely operated vehicle, ROV Lu'ukai – and collected new rock samples from some of its shallowest peaks. With these new samples Sinton and colleagues hope to constrain the timing of the most recent volcanism on Ka'ena.
Provided by University of Hawaii at Manoa 
Friday, May 16, 2014 |
US scientists explore Grenada's huge underwater volcano
Kick'em Jenny volcano has erupted 10 times since 1939, with the most recent eruption in 1990.
NEW YORK, (CMC) -- A team of scientists from the United States has travelled to Grenada, exploring the darkest corners of a huge underwater volcano off the island's coast hoping to better understanding the mysteries of earthquakes and tsunamis, and ultimately saving lives.
President of US Ocean Exploration Trust, Robert Ballard, famous for discovering the Titanic 12,000 feet below the surface of the icy North Atlantic in 1985, has set his sights on exploring the volcano, 'Kick'em Jenny', studying its eruption history and learn more about how underwater volcanoes can pose a threat.
Ballard, who is also director of the Centre for Ocean Exploration at the University of Rhode Island's Graduate School of Oceanography, said the Kick'em Jenny volcano has a history of explosive eruptions, which could have the potential to trigger tsunamis, the effects from which could be felt as far away as the northeastern United States.
According to the US Geological Survey (USGS), the Kick'em Jenny volcano has erupted 10 times since 1939, with the most recent eruption in 1990.
"This is the most hazardous part of our planet, where (tectonic) plates are head-on," said Ballard, noting that the devastating 2011 Japanese earthquake and the 2004 Indian Ocean earthquake and tsunami were both underwater earthquakes.
The American television network, ABC TV, said reporters from its 'Nightline' programme accompanied Ballard and his team of 40 explorers aboard their exploration vessel Nautilus during the final 48 hours of their 90-day voyage, which was documented for an upcoming National Geographic special, 'Caribbean's Deadly Underworld', which premieres Sunday on the US network, Nat Geo WILD.
The conditions around the Kick'em Jenny volcano are so dangerous to humans that Ballard and his team relied on the Remotely Operated Vehicle (ROV) 'Hercules', a 5,000-pound submersible, to be their "eyes and ears inside the volcano," ABC TV reported.
It said as Hercules descends into the volcano, Ballard and his team watch the robot's live cameras from a control room aboard the Nautilus.
After hours of searching, the team made a startling discovery.
"It means that places that we thought there was very little life existing on our plant, we've just opened up a whole other area where life seems to be thriving," Ballard said, adding "a lot of the deep sea is sort of like you know you can think of it as a desert. We just found an oasis in that desert."
On its journey, Hercules took pictures of its surroundings, made maps and collected samples, including organisms living inside the volcano and even reaching inside the volcano's bubbling plume to gather materials, ABC TV said.
It said such discoveries on Ballard's trip could allow scientists to better understand the threats posed by underwater volcanic eruptions.
"And there's no reason to stop, there's 72 per cent of the planet hardly explored. I like to tell children that their generation is the generation that will explore more of earth than all previous generations combined," Ballard said.
http://www.jamaicaobserver.com/latestnews/US-scientists-explore-Grenada-s-huge-underwater-volcano
World's Only Drop-In Volcano, Thrihnukagigur, Opens For Third Season Of Tours (Many oversized images)
http://www.huffingtonpost.com/2014/05/16/thrihnukagigur_n_5309987.html?utm_hp_ref=travel~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Alaska Volcano Quiets Down After Shooting Ash 28,000 Feet
Alaska's Pavlof Volcano, 590 miles southwest of Anchorage, has quieted down after its strongest eruption of the year, but the Alaska Volcano Observatory (AVO) says low-level tremors continue.
The volcano erupted overnight on Monday into Tuesday, sending ash 28,000 feet into the air and…
Alaska's Pavlof Volcano, 590 miles southwest of Anchorage, has quieted down after its strongest eruption of the year, but the Alaska Volcano Observatory (AVO) says low-level tremors continue.
The volcano erupted overnight on Monday into Tuesday, sending ash 28,000 feet into the air and disrupting local flights.
The eruption was the strongest the volcano has emitted in 2013. Scientists first started to see signs of activity on May 16, and they say it's intensified over the past six weeks.
"For some reason we can't explain, it picked up in intensity and vigor," Tina Neal, an observatory geologist, told Reuters.
According to the AVO, as of Thursday, the volcano's activity was still continuing, but at much lower levels than earlier in the week.
"Periods of continuous tremor are likely associated with lava fountaining and minor ash production, but at this level, emission rates are probably very low," the AVO said in its daily volcano update.
But it also noted, "It is possible for conditions to change at any time."
A second Alaska Peninsula volcano continued a low-intensity eruption, the observatory said. Ash from Veniaminof Volcano, 485 miles southwest of Anchorage, has been limited to the area around its 8,225-foot summit, the observatory said.
The eruptions at Pavlof and Veniaminof are unrelated, scientists say.
A third, more remote, Alaska volcano remained restless but was not currently spouting lava or ash, the observatory said.
Cleveland Volcano, 940 miles southwest of Anchorage, began an on-and-off eruptive phase in mid-2011 but has not produced an explosive eruption since May 6, according to the observatory.
http://earthchangesmedia.com/alaska-volcano-quiets-down-after-shooting-ash-28000-feet
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