The Plinian Eruption of 4 April 2009 of Redoubt VolcanoAt the end of March 2009, Redoubt Volcano started a period of explosive eruptions, most of them sending Plinian ash columns into the stratosphere reaching altitudes of 15km and more. At dawn of 4 April, Norbert Fischer and Marco Fulle observed a particularly powerful Plinian eruption from Ninilchik, 75km SE of the volcano. The reported times are local (GMT - 8hr). The associated seismic signal can be seen here (courtesy Alaska Volcano Observatory) | |||
 5h55m, f=50mm. Moonset just five minutes before the onset of the eruption (lower panel). A view taken on 5 April (same orientation and lens, upper panel) helps to exactly localize Redoubt Volcano (center). |  6h06m, f=50mm. The plinian ash cloud reaches the stratosphere (the frame covers a height of 25km at the volcano). Lightning in the ash cloud and red glow (possibly from lava) on the opposite volcano flank at left. |  6h07m, f=50mm. As the ash cloud rises, lightning increases in strenght. Note the fixed position of the red glow at the left of the volcano, possibly due to incandescence from pyroclastic flows, reflected by clouds, on the volcano's north flank. |  6h12m, f=50mm. The red glow on the volcano's flanks fades, whereas lightning continues within the entire ash cloud; the latter expands as quickly as expected in case of major eruption... |
 6h19m, f=20mm. Strong northwesterly winds shift the Plinian ash cloud towards our position on the other side of Cook Inlet (exposure time 4 seconds). |  6h20m, f=20mm. A longer exposure time of 15 seconds clearly shows the rapid expansion of the cloud. Lightning at the cloud base (right), 70 km distant. |  6h24m, f=10mm. The ash cloud reaches Ninilchik, and moves so fast that a 15 sec exposure shows its movement also in an extreme wide angle photo. |  6h40m, f=10mm. Dawn starts north of Ninilchik, while a dark night continues just south of the town where a strong ashfall occurs (left). |
 7h03m, f=10mm. While the ground remains in darkness, the rising sun illuminates the ash cloud which has reached the stratosphere; the landscape assumes an unreal purple colour. |  7h05m, f=10mm. Norbert (right) cannot believe such celestial light may fall on Planet Earth. |  7h47m, f=30mm. A huge lahar reaches the snow-covered plains along Cook Inlet's shore generating dense steam clouds drifting south; the Alaska Range disappears from our view. |  10h, f=85mm. After the ash cloud has dissipated, an unobstructed view from Kenai shows that the volcano is still erupting a dense column of steam and ash. |
| Photos by Marco Fulle. The lens focal length helps to understand the scale; digital camera with 18x24mm sensor. | |||
