May 23, 2008

Things could get much worse...

I've been meaning to post on this very important possibility, but I've been as distracted as usual. Alan Sullivan has been following the ongoing eruption of the volcano at Chaitén. This is from a couple of weeks ago...

....Let’s recall the onset of the eruption. One significant earthquake on April 30 preceded the first explosions; four more accompanied them on May 2. Epicenters were arrayed radially around the caldera. Their locations implied that a very large magma chamber might be released by the eruptive process. After the initial blasts, the eruption settled into a near steady-state, sustained so long that a vast amount of material must have been spewed by now — perhaps doubling the two cubic kilometers of ejecta estimated in the first phase. (Caveat: that’s just a guess.) But the plume has not been punching high enough to matter, in the global scale.

That may change very soon. If the magma conduit is breaking up, and the capping lava dome explodes away, a Tambora-sized event could happen in the next few days. It is plausible that the blowout could be even greater. The tragedies of China, Burma, or Sumatra are trivial in comparison with what may be about to occur. Global climate is already cooling; food supplies are already tight. The Four Horsemen have been stabled for many years. Tonight I can hear their mounts champing...

So what is a "Tambora-sized event?" Tambora exploded in 1815. From Wikipedia: The Year Without a Summer:

The Year Without a Summer, also known as the Poverty Year, The Year There Was No Summer or Eighteen hundred and froze to death, was 1816, in which severe summer climate abnormalities destroyed crops in Northern Europe, the American Northeast and eastern Canada.[1][2] Historian John D. Post has called this "the last great subsistence crisis in the Western world".[3] It appears to have been caused by a volcanic winter.

Chaitén is quiet at the moment, but:

...The Chilean government issued a new statement today. The Volcanism Blog has yet to post one of its elegant translations. I ran the text through Babelfish and got comical results. It’s not geared for science. But there’s nothing funny about what’s happening at the volcano. It is exactly as I suspected. Major dome building is now underway. The geologists were astonished by their flyby yesterday. Seismic signals indicate continued magma movement. The authorities remain worried about a catastrophic blowout. This event is not over. It may continue for weeks or even months before a climactic phase ensues...

I remember "dome building" before Mt St Helens blew. But this seems to be something considerably bigger.

Posted by John Weidner at May 23, 2008 6:49 AM
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