Mahasen formed as a tropical storm over the northern Indian Ocean on May 10, 2013. On May 13, the U.S. Navy’s Joint Typhoon Warning Center (JTWC) reported that Mahasen was moving northward over the Bay of Bengal, headed in the direction of Bangladesh and northeastern India. The storm had maximum sustained winds of 50 knots (95 kilometers per hour) and gusts up to 65 knots (120 kilometers per hour). Within 72 hours, the JTWC reported, sustained wind speeds were expected to increase to 70 knots (130 kilometers per hour).
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image on May 13, 2013. Mahasen lacked a distinct eye, but still sported a rough apostrophe shape typical of strong storms. Clouds extended along the coast of India and over Sri Lanka.
The JTWC reported that the storm was located roughly 630 nautical miles (1,170 kilometers) south-southwest of Kolkata (Calcutta). The JTWC forecast map showed Mahasen moving northward over the Bay of Bengal before turning slightly toward the northeast, making landfall around May 16.
With a history of eruptions throughout the past century, Volcán Copahue showed new signs of life in late 2012 and early 2013. Copahue awoke on December 22, 2012, with a steady volcanic tremor and a few brief explosions.
SERNAGEOMIN, the Chilean National Service of Geology and Mining, reported that the eruption was likely caused by water vaporizing as it interacted with magma rising inside the volcano. (Called a phreatic eruption by volcanologists.) Since then, SERNAGEOMIN described intermittent steam and gas plumes, accompanied by continuing earthquakes. The earthquakes suggest that magma is fracturing rock as it rises from beneath the volcano.
Volcán Copahue is a composite volcano located in the Andes, on the border of Chile and Argentina. This natural-color satellite image shows a blue-tinted gas plume streaming toward the east. The nearest settlement is Caviahue, an Argentinian ski resort. The image was acquired by the Advanced Land Imager (ALI) on Earth Observing-1 on January 5, 2013.
Numerous volcanoes contribute to the landmass of the island of New Britain, the largest in the Bismarck Archipelago of Papua New Guinea. One of the most active of these volcanoes – Ulawun – is also the tallest, with a summit elevation of 2,334 meters (7,657 feet).
This astronaut photograph was taken during the most recent phase of volcanic activity at Ulawun. A plume of white steam and ash extends from the summit crater of the stratovolcano towards the northwest. The plume begins to broaden as it passes the southwestern coast of Lolobau Island, approximately 23 kilometers downwind. Note that the image is oriented such that north is towards the lower left.
Ulawun is also known as “the Father,” with the Bamus volcano to the southwest also known as “the South Son.” The summit of Bamus is obscured by white cumulus clouds (not of volcanic origin) in this image. While Ulawun has been active since at least 1700, the most recent activity at Bamus occurred in the late 19th century. A large region of ocean surface highlighted by sunglint – sunlight reflecting off the water surface—is visible to the north-northeast of Ulawun.
Tolbachik Volcano on Russia’s Kamchatka Peninsula showed signs of unrest in late November 2012. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite detected unusually high surface temperatures and an apparent ash plume on November 29 .
The red outlines in the image approximate the areas with high surface temperatures associated with volcanic activity. The volcanic peaks cast long shadows to the north, thanks to the low angle of the Sun. By the time MODIS observed the region on November 29, the volcano had released a dark brown ash plume that settled on the snow.
Tolbachik is a shield volcano—a low-profile, broad structure with a shape resembling an ancient warrior shield. The volcano has a complex configuration, and the eruptive activity in late November reportedly occurred around the southern cone. Reports described eruptions from two fissures, a volcanic ash plume reaching 3 kilometers (9,800 feet) in altitude, and emissions of sulfur dioxide.
From the ground, the lava lakes on Vanuatu’s Ambrym volcano look something like J.R.R. Tolkien’s Mount Doom. Roiling pools of lava glow a deep orange, spewing fountains of lava and seemingly endless plumes of steam and gas.
From space, the view is more subtle. The Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite captured this natural-color image of activity within Ambrym’s caldera on December 13, 2012. Twin lava lakes on Ambrym’s Marum cone are visible. The larger of the two, which is gray, lies within Mbuelesu crater; to the southwest, Mbuelesu has a secondary crater that contains a pinkish-gray lava lake.
Active lava lakes often have a partly-solid, shiny gray crust that forms as the atmosphere cools their surfaces. The crust is rarely more than 5 to 30 centimeters (2 to 12 inches) thick and usually lasts just a few hours because it continually circulates, breaks, and sinks into the molten lava below. The pink color of the smaller lake suggests that surface was especially agitated and the crust was absent or in the process of sinking back into the lake.