earliest stages of massive eruption

[jose v]

ORIGINAL CAPTION: An amazing new picture from space reveals a volcanic eruption in its earliest stage, with a huge plume of ash and steam billowing skyward and creating a shock wave in the atmosphere. Sarychev Peak on Matua Island is one of the most active volcanoes in the Kuril Island chain, northeast of Japan.
The new photo was taken June 12 from the International Space Station. NASA says volcano researchers are excited about the picture "because it captures several phenomena that occur during the earliest stages of an explosive volcanic eruption."

The main plume appears to be a combination of brown ash and white steam, according to a NASA statement. The vigorously rising plume gives the steam a bubble-like appearance. The surrounding atmosphere has been shoved up by the shock wave of the eruption, scientists said. 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 is probably a transient feature, scientists say, with the eruption plume is starting to punch through. The cloud casts a dark shadow to the northwest of the island.

Often, winds high in the atmosphere sheer a volcano's plume and flatten it out. That didn't happen with this one.

The photo also shows a ground-hugging plume of light gray ash, probably a mix of hot gas and ash in what volcanologists call a pyroclastic flow, descending from the volcano summit. Pyroclastic flows — deadly to anything or anyone in their paths — are known to be up to 600º and rush across the land at 130 mph.

Commercial airline flights are being diverted away from the region to minimize the danger of engine failures from ash intake. The last explosive eruption from Sarychev Peak was in 1989. (NASA/ISS/Earth Observatory, text Imaginova)