ISS020-E-9048
This detailed astronaut photograph is exciting to volcanologists because it captures several phenomena that occur during the earliest stages of an explosive volcanic eruption. The main column is one of a series of plumes that rose above Matua Island on June 12. The plume appears to be a combination of brown ash and white steam. The vigorously rising plume gives the steam a bubble-like appearance.
In contrast, the smooth white cloud on top may be water condensation that resulted from rapid rising and cooling of the air mass above the ash column. This cloud, which meteorologists call a pileus cloud, is probably a transient feature: the eruption plume is starting to punch through. The structure also indicates that little to no shearing wind was present at the time to disrupt the plume. (Satellite images acquired 2-3 days after the start of activity illustrate the effect of shearing winds on the spread of the ash plumes across the Pacific Ocean.)
By contrast, a cloud of denser, gray ash - probably a pyroclastic flow - appears to be hugging the ground, descending from the volcano summit. The rising eruption plume casts a shadow to the northwest of the island (image top). Brown ash at a lower altitude of the atmosphere spreads out above the ground at image lower left. Low-level stratus clouds approach Matua Island from the east, wrapping around the lower slopes of the volcano. Only about 1.5 kilometers of the coastline of Matua Island (image lower center) are visible beneath the clouds and ash.
ISS020-E-9861
The Fold is a geologic structure called a monocline—layers of generally flat-lying sedimentary rock with a steep, one-sided bend, like a carpet runner draped over a stair step. Geologists think that monoclines on the Colorado Plateau result from faulting (cracking) of deeper and more brittle crystalline rocks under tectonic pressure; while the crystalline rocks were broken into raised or lowered blocks, the overlaying, less brittle sedimentary rocks were flexed without breaking.
The portion of the Waterpocket Fold illustrated in this image includes layered rocks formed during the Mesozoic Era (about 250 – 65 million years ago). The oldest layers are at the bottom of the sequence, with each successive layer younger than the preceding one going upwards in the sequence. Not all of the Fold's rock layers are clearly visible, but some of the major layers (units to geologists) can be easily distinguished.
The top half of the image includes the oldest rocks in the view: dark brown and dark green Moenkopi (Trm) and Chinle (Trc) Formations. Moving toward the foot of the mesa, two strikingly colored units are visible near image center: light red to orange Wingate Sandstone (Jw) and white Navajo Sandstone (Jn). Beyond those units, reddish brown to brown Carmel Formation (Jc) and Entrada Sandstone (Je) occupy a topographic bench at the foot of a cliff. The top of the cliff face above this bench—Big Thomson Mesa—is comprised of brown Dakota Sandstone (Kd). This sequence represents more than 100 million years of sediments being deposited and turned into rock. Much younger Quaternary (2-million- to approximately 10,000-year-old) deposits are also present in the view.
The area shown in this astronaut photo is located approximately 65 kilometers (about 40 miles) southeast of Fruita, Utah, near the southern end of Capitol Reef National Park.
ISS020-E-16279
The islets of Millennium Island are readily visible in this astronaut photograph as irregular green vegetated areas surrounding the inner lagoon. The shallow lagoon waters are a lighter blue than the deeper surrounding ocean water; tan linear “fingers” within the lagoon are the tops of corals. The two largest islets are Nake Islet and South Islet, located at the north and south ends of Millennium Island respectively. The ecosystem of Millennium Island is considered to be relatively pristine despite periods of human habitation, guano mining, and agricultural activities, and the island has been recommended as both a World Heritage site and Biosphere Reserve.
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This detailed astronaut photograph depicts the summit caldera of the volcano. The huge caldera—6 kilometers in diameter and 1,100 meters deep—formed when Tambora’s estimated 4,000-meter-high peak was removed, and the magma chamber below emptied during the April 10 eruption. Today the crater floor is occupied by an ephemeral freshwater lake, recent sedimentary deposits, and minor lava flows and domes emplaced during the nineteenth and twentieth centuries. Layered tephra deposits are visible along the northwestern crater rim. Active fumaroles, or steam vents, still exist in the caldera.
In 2004, scientists discovered the remains of a village, and two adults buried under approximately 3 meters of ash in a gully on Tambora’s flank—remnants of the former Kingdom of Tambora preserved by the 1815 eruption that destroyed it. The similarity of the Tambora remains to those associated with the AD 79 eruption of Mount Vesuvius has led to the Tambora site’s description as “the Pompeii of the East.”
ISS020-E-9011
The eastern side of the river is dominated by industrial development associated with the Pohang Iron and Steel Company (POSCO) steelyard. This development (image center) includes large factory and storage buildings with striking light blue and light red rooftop. Green vegetated hills and mountains border the urban area to the east, west, and south, and several vegetated hills remain within the industrial area. Numerous boat wakes are also visible to the east-northeast of the POSCO steelyard docks.
While the Pohang area has been occupied by small fishing villages since approximately 1500 BC, development of an urban area only began in 1930 when harbor facilities were constructed. POSCO began construction of a large steel mill and associated facilities in 1968, with production of steel products commencing in 1972. The steel industry is still a major component of the city’s economic base, but recent efforts to lessen dependance on heavy industry has fostered new interest in environmentalism and culture within Pohang.
ISS020-E-21140
Sinuous flow levees marking individual lava flows are perhaps the most striking volcanic features visible in the image. Flow levees are formed when the outer edges of a channelized lava flow cool and harden while the still-molten interior continues to flow downhill. Numerous examples radiate outwards from the peaks of both Pico de Teide and Pico Viejo. Brown to tan overlapping lava flows and domes are visible to the east-southeast of the Teide stratovolcano. Increased seismicity, carbon dioxide emissions, and fumarolic (gas and smoke) activity within the Las Cañadas caldera and along the northwestern flanks of the volcano were observed in 2004. Monitoring of the volcano to detect renewal of activity is ongoing.
ISS020-E-26195
The concentric ring structure of the Aorounga crater—renamed Aorounga South in the multiple-crater interpretation of SIR data—is clearly visible in this detailed astronaut photograph. The central highland, or peak, of the crater is surrounded by a small sand-filled trough; this in turn is surrounded by a larger circular trough. Linear rock ridges alternating with light orange sand deposits cross the image from upper left to lower right; these are called yardangs by geomorphologists. Yardangs form by wind erosion of exposed rock layers in a unidirectional wind field. The wind blows from the northeast at Aorounga, and sand dunes formed between the yardangs are actively migrating to the southwest.
ISS020-E-28123
While hot springs and steam vents are still active on Mount Hood, the last eruption from the volcano occurred in 1866. The volcano is considered dormant, but still actively monitored. Separate phases of eruptive activity produced pyroclastic flows and lahars that carried erupted materials down all of the major rivers draining the volcano. Gray volcanic deposits extend southwards along the banks of the White River (image lower left) and form several prominent ridges along the southeast to southwest flanks of the volcano. The deposits contrast sharply with the green vegetation on the lower flanks of the volcano.
The Mount Hood stratovolcano—a typically cone-shaped structure formed by layered lava flows and explosive eruption deposits—hosts twelve mapped glaciers along its upper flanks. Like other glaciers in the Pacific Northwest, the Hood glaciers have been receding due to global warming, and they have lost an estimated 61 percent of their volume over the past century. The predicted loss of glacial meltwater under future warming scenarios will have significant effects on regional hydrology and water supplies.
ISS020-E-28072
This astronaut photograph highlights the jagged coastline of the southern Crimean Peninsula and the various docking areas of Sevastopol. The urban area is light gray, and it is bounded to the north and west by the Black Sea, to the south by vegetated (light green) and fallow (tan) agricultural fields, and to the east by the city of Inkerman and vegetated uplands (deep green). The city of Balaklava, to the south, houses another relic of the Cold War—an underground Soviet submarine base that is now open to the public as a monument. The Chernaya River issues into the Black Sea near Inkerman, flowing into the Sevastopol Inlet to the west.
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The two largest valley glaciers in the image, Silverthrone Glacier and Klinaklini Glacier, both flow towards Knight Inlet to the south (not shown). Several moraines—accumulations of rock and soil debris along the edges and surface of a glacier—are drawn out into long, dark lines by the flowing ice, and they extend along the length of both glaciers. The confluence of the two glaciers at image center illustrates how a moraine located along the side of a glacier can become a medial moraine, in the center of the joined ice mass. Smaller valley glaciers are visible near Mount Silverthrone.
