Anak Krakatau eruption July 2009 - anatomy of an explosion

The crater with the new cone resembling a small lava dome has been inactive for many hours. The conduit is effectively sealed, only some fumaroles let small amounts of gas escape. (Photo: Tom Pfeiffer)
The crater with the new cone resembling a small lava dome has been inactive for many hours. The cond... [info]
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The first signs that something is happening inside are isolated rockfalls on the flanks of the cone. (Photo: Tom Pfeiffer)
The first signs that something is happening inside are isolated rockfalls on the flanks of the cone.... [info]
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Several minutes later, the rockfalls become more frequent and intense.  (Photo: Tom Pfeiffer)
Several minutes later, the rockfalls become more frequent and intense. (Photo: Tom Pfeiffer) [info]
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About 10 minutes after the onset, the rockfalls and the sliding of material are continous and whirl up a plume of ash. The whole cone, ready to explode, is now vibrating. (Photo: Tom Pfeiffer)
About 10 minutes after the onset, the rockfalls and the sliding of material are continous and whirl ... [info]
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The crater of the cone explodes. In a fragment of a second, a dense plume of ash and exploding rock is ejected at high speed; the picture is taken at the distance of reaction time... thousands of rocks have already left above the frame of the picture. A powerful detonation sound hits us a second later. (Photo: Tom Pfeiffer)
The crater of the cone explodes. In a fragment of a second, a dense plume of ash and exploding rock ... [info]
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Same view a fraction of seconds later. Rocks and ash continue to explode. (Photo: Tom Pfeiffer)
Same view a fraction of seconds later. Rocks and ash continue to explode. (Photo: Tom Pfeiffer) [info]
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After less than 1 second into the eruption, the dense mass of rocks and hot lava that had been plugging the conduit explodes and starts to form a rising ash plume. Many blocks ejected at high speed are advancing in all directions above and to all sides of the ash plume. (Photo: Jorge Santos)
After less than 1 second into the eruption, the dense mass of rocks and hot lava that had been plugg... [info]
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Zoom onto the expanding ejected plug of the explosion; only few of the blocks are actually glowing red. At night, this means that most blocks won't be visible! (Photo: Tom Pfeiffer)
Zoom onto the expanding ejected plug of the explosion; only few of the blocks are actually glowing r... [info]
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A fraction of a second later, the largest blocks are falling onto the slope of the cone, leaving dense trails of ash behind in the air, while the ash cloud expands, parts with a strong lateral component. (Photo: Jorge Santos)
A fraction of a second later, the largest blocks are falling onto the slope of the cone, leaving den... [info]
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The largest blocks fall leaving huge scary fingertrails of ash behind. At the base of the eruption, pyroclastic flows form. (Photo: Tom Pfeiffer)
The largest blocks fall leaving huge scary fingertrails of ash behind. At the base of the eruption, ... [info]
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The ash cloud expands and small pyroclastic flows develop from dense ash both ejected and whirled up by impacts on the upper flanks of the cone. (Photo: Jorge Santos)
The ash cloud expands and small pyroclastic flows develop from dense ash both ejected and whirled up... [info]
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After about 10 seconds, the first blocks impact on the water, while the ash could and the small pyroclastic flows on the flank of the cone expand and develop further. (Photo: Jorge Santos)
After about 10 seconds, the first blocks impact on the water, while the ash could and the small pyro... [info]
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About 15 seconds after the beginning of the eruption, most bombs and blocks have fallen, the ash cloud continues to rise and the pyroclastic flows have lifted off ground. (Photo: Jorge Santos)
About 15 seconds after the beginning of the eruption, most bombs and blocks have fallen, the ash clo... [info]
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Another explosion on 3 July has left the whole crater with dusty impacts of blocks and a rising ash plume above it. (Photo: Jorge Santos)
Another explosion on 3 July has left the whole crater with dusty impacts of blocks and a rising ash ... [info]
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After the first impact of the eruption is over, the ash plume continues to rise, often reaching more than 1 km in elevation. (Photo: Tom Pfeiffer)
After the first impact of the eruption is over, the ash plume continues to rise, often reaching more... [info]
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The ash plume has lost its turbulence and power and is now expaning at elevation by atmospheric diffusion and wind. Ash starts raining down... (Photo: Tom Pfeiffer)
The ash plume has lost its turbulence and power and is now expaning at elevation by atmospheric diff... [info]
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While it's raining ash from the explosion that just passed, another, smaller explosion takes place. it was typical to observe a series of weakening explosions after the first powerful blasts. Probably, this can be interpreted by downward progression of explosive pressure release inside the conduit. (Photo: Tom Pfeiffer)
While it's raining ash from the explosion that just passed, another, smaller explosion takes place. ... [info]
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The ash plumes from two explosions are now drifting high above us and illuminated by the evening sun. (Photo: Tom Pfeiffer)
The ash plumes from two explosions are now drifting high above us and illuminated by the evening sun... [info]
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A third, much weaker eruption takes place. In fact, only ash is exiting the crater rim.  (Photo: Tom Pfeiffer)
A third, much weaker eruption takes place. In fact, only ash is exiting the crater rim. (Photo: Tom... [info]
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The diffuse gray ash plume from the third eruption drifts far below the now very diffuse plume of the first and second explosion, colored red by the setting sun.  (Photo: Tom Pfeiffer)
The diffuse gray ash plume from the third eruption drifts far below the now very diffuse plume of th... [info]
(3528 Hits)
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