Satellite Data Yield New Understanding Of How Galápagos Volcanoes Are Formed And May Erupt In The Future
Courtesy Hawaii Volcano National Park
HAWAI`I ISLAND, Hawaii — The chance transit of a satellite over the April 2009 eruption of Fernandina volcano — the most active in South America's famed Galápagos archipelago — has revealed for the first time the mechanism behind the characteristic pattern of eruptive fissures on the island chain's volcanoes, according to a new study by University of Miami (UM) and U.S. Geological Survey (USGS) scientists. Their model not only sheds light on how Galápagos volcanoes grow, which has been a subject of debate since Darwin's time, but may also help in forecasting the locations of future eruptions, adding to the vast scientific knowledge acquired by study of this iconic island chain.
In the study, Marco Bagnardi, a doctoral candidate at the UM Rosenstiel School of Marine & Atmospheric Science (RSMAS) and visiting scientist at USGS' Hawaiian Volcano Observatory, analyzed surface deformations on Fernandina from European Space Agency (ESA) ENVISAT satellite images acquired just two hours before the 2009 eruption. He sought to explain why Hawaiian and Galápagos volcanoes, while similar in some respects, show different eruptive patterns. Eruptions from Hawai'i's volcanoes tend to occur along narrow rift zones that extend radially from the summit, while the shields of western Galápagos volcanoes have eruptive fissures that circle the summit near the calderas but are oriented radially on the flanks below.
Bagnardi found that magma began moving away from Fernandina's reservoir as a sill, or horizontal feature, before rotating vertically and erupting in a fissure perpendicular to the summit on the volcano's southwest flank. A sill also fed the 2005 eruption at Fernandina, but that magma moved upward to form a fissure circling the volcano's summit closer to the top. These data suggest that sills feed all eruptive activity in the Galápagos but that they rotate in different ways as they propagate toward the host volcano's surface.
"Our findings have literally turned our perspective by 90 degrees," Bagnardi said. "For decades, we thought that eruptions in the Galápagos were starting with the intrusion of vertical blade-like bodies. We now know this is not the case."
"Without knowing why the fissures are arranged the way they are, we had no way to infer the geologic history of the volcanoes and how they evolved over time," said USGS geophysicist Mike Poland, a co-author of the study. "This research allows scientists to better model how the volcanoes grow and behave, especially with respect to past and future activity," Poland said. "You can't move forward with solving the puzzle because you are missing a key part of the story. This work fills in a major missing piece and will allow better interpretations of a multitude of parameters about Galapagos volcanoes."
UM RSMAS is part of a long-term satellite-based monitoring program of the Galápagos volcanoes using Interferometric Synthetic Aperture Radar (InSAR), a technique that uses repeat satellite observations to measure millimeter-scale ground displacements. Bagnardi credited the "extremely fortunate" timing of data collected by the ENVISAT satellite, which passed over the island just when magma was already on its way toward the surface. Fernandina erupts every four to five years, on average, and the satellite passed over the archipelago only once every several days, he said.
The team theorizes that Hawaiian and Galápagos volcanoes behave differently because neighboring volcanoes of the Galápagos grew concurrently and did not affect one another as they formed. Hawaiian volcanoes, however, grow sequentially, meaning that older volcanoes control the structural development, including eruptive patterns, of younger edifices.
Based on the relations between deformation and eruptions at Fernandina in 1995 and 2005, the authors argue that the next eruption of Fernandina will be from a fissure circling the volcano's summit on the southwest side of the caldera in the area uplifted by the 2009 sill intrusion.
"Unfortunately, we are still not able to predict the timing of future eruptions in the Galápagos," Bagnardi said. "However, providing a forecast for the location and type of eruption is a step in the right direction."
Satellite imagery used in the study was also provided by the Japanese Space Exploration Agency (JAXA). This research was supported by the National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF).
The paper in Earth and Planetary Science Letters, "A New Model for the Growth of Basaltic Shields Based on Deformation of Fernandina Volcano, Galápagos Islands," by Marco Bagnardi, Falk Amelung and Michael P. Poland, is available online.
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Lava flows still active, burning forests north of Puu Oo
POSTED: 04:57 p.m. HST, Oct 23, 2013
LAST UPDATED: 01:44 a.m. HST, Oct 24, 2013
The northeast spatter cone in Kilauea Volcano's Puu Oo vent continues to feed the Kahaualea 2 lava flow, which is burning through forests to the north, the Hawaiian Volcano Observatory reports.
On Monday, observatory geologists found active breakouts in the northern half of the flow, with a narrow finger extending northeast into the forest.
The Kahaualea 2 flow was also burning forest at other contact points along its northern edge, the scientists said Wednesday.
Meanwhile, the so-called Peace Day flow was weakly active above the pali. Geologists on Monday mapped a small breakout consisting of two lobes from the Peace Day tube about 1.9 miles southeast of Puu Oo that had minor pahoehoe activity.
The eruption in Kilauea's middle east rift zone started with a fissure eruption on Jan. 3, 1983, and has continued with few interruptions at Puu Oo, or temporarily from vents within a few kilometers to the east or west.
A fissure eruption on the upper east flank of Puu Oo on Sept. 21, 2011, drained the lava lakes and fed the Peace Day flow, which advanced southeast through the abandoned Royal Gardens subdivision to the ocean inside Hawaii Volcanoes National Park.
Since late December 2011, the flows have remained intermittently active on the pali and the coastal plain and finally re-entered the ocean on Nov. 24.
The Kahaualea flow, which started from the spatter cone/lava lake at the northeast edge of the Puu Oo crater floor in mid-January, was dead by late April, But a new flow, Kahaualea 2, became active in the same area in early May.
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Kamchatka Volcano Spews Ash 5km Into Air
Zhupanovsky volcano (archive)
© RIA Novosti. S. FedorenkoMOSCOW, October 24 (RIA Novosti) – A volcano on the east of Russia's Kamchatka Peninsula has thrown ash five kilometers (3.1 miles) into the air, the Emergencies Ministry said Thursday.
The Zhupanovsky volcano spurted the ash Wednesday night, with the resultant trail spreading 40 kilometers southeast, the ministry's local office said in a statement.
The layer of ash was up to one millimeter thick. No residential areas affected, the ministry added.
The volcano was given an aviation color code yellow, indicating an alert level that means the "volcano is exhibiting signs of elevated unrest above known background levels."
According to scientists, the volcano's last major eruption happened around 800 to 900 AD but low-level eruptions have since occurred periodically. The last one was in 1959.
http://en.ria.ru/russia/20131024/184330061/Kamchatka-Volcano-Spews-Ash-5km-Into-Air.html
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Indonesia's Mount Sinabung Volcano Erupts, Villages Covered In Thick Ash
10/24/13 
MEDAN, Indonesia -- MEDAN, Indonesia (AP) — A volcano in western Indonesia erupted on Thursday, unleashing a column of dark volcanic material high into the air weeks after villagers were returning home from an earlier eruption, officials said.
The explosion at Mount Sinabung, located in North Sumatra province, shot black ash 3 kilometers (nearly 2 miles) into the air, but there were no reports of injuries or damage, said National Mitigation Agency spokesman Sutopo Purwo Nugroho.
He said villages, farms and trees around the 2,600-meter (8,530-foot) -high rumbling volcano were covered in thick gray ash, prompting authorities to evacuate more than 3,300 people. Most were from two villages within 3 kilometers (nearly 2 miles) of the mountain in Karo district.
No lava or debris spewed from the volcano, and nearby towns and villages were not in danger, but authorities warned tourists to stay away from the danger zone located 1.5 kilometers (1 mile) from the crater, Nugroho said.
Last month, more than 15,000 people were forced to flee when the volcano rumbled to life after being dormant for three years, belching ash and smoke and igniting fires on its slopes.
The volcano's last major eruption in August 2010 killed two people and forced 30,000 others to flee. It caught many scientists off guard because it had been quiet for four centuries.
Mount Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin.
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