Monday, December 12, 2011

Quakes Stop At El Hierro, But Eruption Continues

Earthquake activity has all but ceased at El Hierro volcano in the Canary Islands, however the eruption is ongoing. There has been much speculation as to whether or not the cessation of earthquakes indicates that the eruption might be dying down. This is not the case. As many seismologists and volcanologists have pointed out, earthquakes typically precede volcanic eruptions, and sometimes stop when the vent or eruption reaches a more stable phase. New data indicates that the submarine vent at El Hierro has grown in size, and webcams still show strong 'jacuzzi' action.

This eruption, in my opinion, looks like it will be a long term one. The many thousands of earthquakes that preceded the eruption indicate a large magma chamber. Earthquakes are caused when rock breaks apart, slips, or fractures. Given the size, depth, and other locational data, it appears that the magma chamber is at least as large as the island itself, although without more advanced analysis, this is just speculation on my part.

The characteristics of this eruption are similar to the volcano Loihi in Hawaii. Loihi is periodically active off of Hawaii's South coast, and will eventually build a new island. The main difference between Loihi and El Hierro are the depths at which they are located. El Hierro's new vent is much shallower than Loihi and has a much better chance of breaching the surface of the ocean in our lifetime, and possibly during this current eruption, than Loihi. Loihi is assumed to breach the surface at some point within the next 10,000 years (too bad we won't be around to see it!). El Hierro's vent is much closer to the surface- within 100 meters, and given the pace of the eruption, it is still quite likely some lucky people will be able to see it born.

So long story short, the eruption continues even though earthquakes have pretty much stopped. Harmonic tremor does continue to register a steady stream of underwater explosions, and the vent is still quite active. At this pace, I would theorize that the volcano would break the water's surface in the next month or so, but of course, that's up to the volcano.

A lot of speculation is also taking place regarding El Hierro that has no basis in fact whatsoever. The blog suggested that a NASA satellite photo showed a 'plume' originating from the vent area. This is incorrect. Clouds do form over volcanoes, as they form over pretty much anything else. This cloud over the vent is a COINCIDENCE, nothing more, nothing less. The same dangerous sort of speculation has occurred on other blogs before, namely the blog of a guy who calls himself "Dutchsinse", a sensationalist doomsayer. He incorrectly reported an eruption at the Pisgah Crater using the same erroneous methods. When he saw a cloud on NASA satellite images over the volcano, he assumed the cloud actually came from the volcano, which is impossible since it is a monogenetic cinder cone with no historical activity.

The publicity Dutchsinse got on the web actually prompted the USGS to issue a statement denying his claim, to which he actually chose to start a war of words with the professional government agency. This sort of speculation is damaging to the credibility of bloggers, and to scientists who are actually doing all the work. Just remember, there are two types of bloggers in regards to volcanoes: Those that know what they're talking about, like Jon Frimann, myself, or other enthusiasts, and then there are those that just want to generate hype to get more ad revenue, at the expense of your intelligence.

Keep it real, keep it scientific, and get the facts straight!

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