Chaiten is not a “normal” volcano. It is a crater amid hills. There is no mountain. Chaiten does not have “sides. If you look at the Landsat photos, you will see only irregular upland, with a crater in the midst. Why is there no mountain? Because on the rare occasions when Chaiten erupts, it ejects straight up like a cannon, with immense force. So far there have apparently been no major pyroclastic collapses of the eruption plume. If there were, the town of Chaiten might be destroyed. It has only been dusted with ash. Apparently the cannon shots end as abruptly as they begin. Very little of the ejecta falls nearby. This is why there is no mountain. Do you see the significance? Chaiten is designed for maximum impact on global climate. Its ash goes straight into the stratosphere.

Fortunately Chaiten is located at a high latitude in the southern hemiphere, not on the equator like Pinatubo — site of the last eruption big enough to affect world climate. After Pinatubo girdled the tropics with haze, there was a drop in temperature and an increase in precipitation on a global scale. The effect faded within a couple of years. Initially Chaiten’s plumes will feed into the southern hemisphere polar vortex. In winter the South Pole is dark for months — no sunlight to block. But eventually Chaiten’s plume will mix globally. Now the key question is how long will the explosions continue? Last night I saw a long streamer on weather satellite imagery. It originated near Chaiten, and I don’t think it was a cirrus cloud.

The plume of smoke fired into the troposphere shows up beautifully on the satellite image:

--

Manish Ghosh