Chaitén Climax
After several weeks of Plinian eruption, Chile’s Chaitén volcano showed major seismic changes today. Emergency authorities released a lengthy bulletin. The Volcanism Blog has done a superb job with timely translations from the Spanish. I have viewed the Chilean sources, but my Spanish is too rudimentary for reading them, and translation programs would probably have difficulty with the geological terms. Here is a key passage:
Over the past two days marked changes have been witnessed in the seismic activity [of the volcano]. A swarm of earthquakes, mainly of the HB [hybrid] type, has occurred, which is interpreted as related to a fracturing of the main conduit with subsequent ascent of magmatic fluids by the conduit and also through the dome. The later predominance of LP type earthquakes confirms the seismic instability of the system, the origin of which is related to the evident movement of magmatic fluids. In consequence there remains a certain possibility of future major explosions causing the destruction, in whole or in part, of the dome and the generation of pyroclastic flows through the collapse of the column. Nor can the possibility of new lateral explosions be disregarded.
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 released 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.
Update: 9:30 PM EDT: I can see it on the satellite image now. Plume height is building rapidly. The next image should be released around 11 PM EDT. US images are updated every 20 minutes, but South America gets short shrift. I’ll stay up and add another update.
Update 2: 11:30 PM EDT: New image out. It is ambiguous. There is a massive upper level moisture plume over the region. Enhanced returns are present around the volcano, but I can’t be sure what is cloud, what is ash. Tomorrow the weather should begin a slow clearing trend, and we’ll get a better look. Meanwhile, welcome to the end of Al Gore’s fantasy world.








