Eruption of Stromboli Volcano, Italy

The mild eruptions of Italy’s Stromboli Volcano are so frequent and numerous that an entire style of volcanism—strombolian—is named after the volcano. Strombolian eruptions are characterized by nearly continuous lava fountaining, accompanied by emissions of gas, ash, and volcanic bombs. The sight of that lava spraying into the sky at night has led people to nickname Stromboli the “Lighthouse of the Mediterranean.”
This natural-color satellite image shows the island of Stromboli, the volcano’s cloud-covered summit, and a thin volcanic plume on January 13, 2011. The image was acquired by the Advanced Land Imager aboard Earth Observing-1 (EO-1).
The volcanic island has been building, according to geologists, for nearly 200,000 years. Historical records of eruptions at Stromboli date back 2,400 years, and carbon dating suggests that the volcano has been almost continuously active for at least 1,400. The current eruption has been going on uninterrupted since 1932. For most of the past 5,000 years, eruptions and venting have sprung from the Sciara del Fuoco (Stream of Fire), a large collapse scar on the northwest side of the island.
The peak of the island volcano stands 924 meters (3,030 feet) above sea level, but in fact the entire structure rises more than 2,000 meters (6,500 feet) from the sea floor. The volcano is a result of the subduction of the African tectonic plate as it collides with and slides under the Eurasian plate.
Today, a few hundred people call the island home, though past populations counted in the thousands. In Jules Verne's novel Journey to the Center of the Earth (Voyage au Centre de la Terre), Axel and Otto Lidenbrock finish their journey by climbing out through Stromboli.
References
Geology.com (n.d) Stromboli, Italy. Accessed January 18, 2011.
Global Volcanism Program. (2010). Stromboli. Accessed January 18, 2011.
Rosi, M., Bertagnini, A., Landi, P. (2000). Onset of the persistent activity at Stromboli Volcano (Italy). Bulletin of Volcanology, 62 (4), 294–300.
Stromboli online. (2010). Stromboli - the volcano. Accessed January 18, 2011.
Nasa Earth Observatory del 22 gennaio 2011

A Clear View of the Alps

The Alps form a crescent stretching from the Mediterranean coasts of Italy and France to Vienna, Austria. On January 17, 2011, clear skies afforded the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite an uninterrupted view of the mountain range. This natural-color image shows snow-capped mountains interspersed with vegetated valleys. Clouds snake through valleys in the north and west, and a nearly continuous cloud bank fills the Po Valley in the south, but skies over the mountains are clear.
The Alps’s began forming tens of millions of years ago, when the African tectonic plate slowly collided with the European plate. The plate collision helped close the western part of the ancient Tethys Sea and lifted up the massive European mountain chain that persists today.
Across the Earth, some mountain ranges are gaining elevation through tectonic uplift, while others are losing elevation through erosion. A study published in Tectonophysics in 2009 found that the Alps are doing both. The actions of glaciers and rivers scrape away fine sediment, which is carried away by water and wind. As this happens, the mountain range loses weight, lightening the load for the Earth’s crust. So just as ice and water scrape off the top, deeper rock layers push up from below. In the Alps, these processes appear to be in equilibrium, keeping the mountain range at a near-constant elevation.
In the Alps region, the valleys have attracted as much scientific attention as the peaks. Over hundreds of thousands of years, advancing Pleistocene glaciers ground away massive quantities of rock, leaving broad, U-shaped valleys. In between glacial advances, rivers carved deep, V-shaped gorges in many valley floors. Geologists long differed about how the steep, river-carved gorges could persist once the glaciers re-advanced. Many thought each new advance would wipe out the underlying gorge, and that the gorges seen today must have been carved since the last glacial episode ended.
But a study published in Nature Geoscience in 2011 argued that many of the steep gorges at the bottoms of the Alps probably persisted through multiple glacial episodes. After mapping more than 1,000 gorges, and calculating the rate at which rivers could have eroded bedrock since the last glacial episode, the researchers concluded that rivers could not work fast enough to carve such deep gorges. The depths of the gorges indicate much older formations. As glaciers re-advanced, the researchers concluded, sediment filled the deep gorges and preserved them below glacial ice. After the glaciers retreated again, fresh rivers cleaned out the sediments and continued carving away at the bedrock.
References
Champagnac, J.-D., Schlunegger, F., Norton, K., von Blanckenburg, F., Abbühl, L.M., Schwab, M. (2009). Erosion-driven uplift of the modern Central Alps. Tectonophysics,474, 236–249.
Dixon, J.L. (2011). Deceptively old Alpine gorges. Nature Geoscience, 4, 8–9.
Encyclopedia Britannica. (2011). Alps. Accessed January 19, 2011.
Lamb, M.P., Fonstad, M.A. (2010). Rapid formation of a modern bedrock canyon by a single flood event. Nature Geoscience, 3, 477–481.
Montgomery, D.R., Korup, O. (2011). Preservation of inner gorges through repeated Alpine glaciations. Nature Geoscience, 4, 62–67.
Romans, B. (2011, January 8). Rapid canyon formation and uniformitarianism. Clastic Detritus. Accessed January 21, 2011.
Science Daily. Science Reference: Geology of the Alps. Accessed January 19, 2011.
Science Daily. (2009, November 6). Are the Alps Growing or Shrinking? Accessed January 19, 2011.
Stricherz, V. (2010, December 5). New research shows rivers cut deep notches n theAlps’ broad glacial valleys. EurekAlert. Accessed January 21, 2011.
Wikipedia. (2011, January 16). Alps. Accessed January 19, 2011.
NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.
Instrument: Terra - MODIS
Nasa Earth Observatory del 21 gennaio 2011

Activity at Mt. Etna

In mid-January 2011, Europe’s largest and most active volcano rumbled with new energy and lit up the Sicilian night with a fountain of lava. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image of the east coast of Sicily and of Mount Etna as it was spewing ash or steam on January 11, before the lava eruption.

According to news reports from Italy, tremors were detected around Mount Etna on the evening of January 11; by the next evening, lava was shooting hundreds of feet into the air and flowing toward the western wall of the Valle del Bove. An ash plume from the eruption shuttered Fontanarossa Airport in nearby Catania (Sicily’s second-largest city) for much of January 12, with flights diverted or canceled. To date, there have been no reports of injuries.

The massive 3,350-meter-high volcano is one of the most consistently active volcanoes in the world, and accounts of its rumblings go back to 1500 B.C. Since at least October 2010, the volcano was showing signs of unrest that slowly built to the January 12 eruption.

An ongoing collection of ground-based photos and webcams of the eruption can be viewed online.

1.
References
2. Global Volcanism Program (n.d.) Etna. Accessed January 14, 2011.
3. Global Volcanism Program (2011, January 12) Weekly Volcanic Activity Report. Accessed January 14, 2011.
4. MSNBC/Our Amazing Planet (2011, January 13) Mount Etna blasts lava, ash into the sky. Accessed January 14, 2011.
5. Volcano Live (n.d.) Mount Etna Volcano. Accessed January 14, 2011.

NASA image courtesy of the MODIS Rapid Response Team, Goddard Space Flight Center. Caption by Michael Carlowicz.

Instrument:
Terra - MODIS

Nasa Earth Observatory del 15 gennaio 2011