After reading the recent news about Chile’s Puyehue-Cordon Caulle volcanic eruption I was struck by the obvious omission of “why” this volcano may have erupted after lying dormant for over fifty years and how this could be highly relevant to the people of Japan and the global community:

Smoke over the border … fire in the sky

June 7, 2011

SANTIAGO: Southern Chile’s Puyehue volcano is now calm after raining down ash and forcing thousands to flee on Saturday. The cloud of soot, estimated to be 10 kilometres high, darkened skies as far away as Argentina.

A light drizzle rained down on the volcano on Sunday, helping to mitigate the effects of the airborne ash somewhat, while the mountain appeared to go quiet one day after having rumbled to life.

Puyehue is 870 kilometres south of the capital Santiago, in the Cordon Caulle complex nestled in the Andes mountains. Its last major eruption was in 1960, following an earthquake.  MORE

You will note that the above article, like so many others, does mention that this volcano erupted in 1960 “following an earthquake.” What has been omitted is that on May 22, 1960, the most powerful earthquake ever recorded on Earth, rating 9.5 on the moment magnitude scale struck Chile, and the volcanic eruption occurred two days later.  The 1960 Great Quake was a mega-thrust quake and unlike other earthquakes which strike on an everyday basis – subduction zone earthquakes are quite different than strike-slip quakes. There are other types of earthquakes, however, in my opinion, those are not relevant to this eruption. Keep this information in mind on you continue to read. 

To complicate matters for the casual observer, some Internet Sites are remarking that this eruption was strange for two different reasons:

Something Strange With Volcano Eruption in Chile

(Excerpts)

The thing is, for some unknown reason, as of this writing, eight earthquakes near magnitude 5 have shook the earth near the Puyehue volcano. The problem is, the earthquakes are located 20 to 40 miles away from the eruption! Very Strange Indeed. (Strange because one would think that the earthquakes associated with a given erupting volcano would be very close to the volcano itself. Instead, these strong quakes are apparently tectonic.)

There’s something brewing or interacting quite a distance from the eruption, but is quite obviously directly related. We’re talking about enormous energies here.

In addition, apparently the volcano itself has not erupted from it’s old caldera. Instead, it has ripped a huge gash into the surface of the earth 6 miles long by 3 miles wide, 2.5 miles away! Amazing.  MORE

In order to understand why volcanoes oftentimes erupt after subduction zone earthquakes it is necessary to look into the geophysics of these types of eruptions:

SUBDUCTION ZONE VOLCANISM

The most volcanically active belt on Earth is known as the Ring of Fire, a region of subduction zone volcanism surrounding the Pacific Ocean. Subduction zone volcanism occurs where two plates are converging on one another. One plate containing oceanic lithosphere descends beneath the adjacent plate, thus consuming the oceanic lithosphere into the earth’s mantle. This on-going process is called subduction. As the descending plate bends downward at the surface, it creates a large linear depression called an oceanic trench. These trenches are the deepest topographic features on the earth’s surface. The deepest, 11 kilometers below sea level, is the Mariana trench, which lies along the western margin of the Ring of Fire. Another example, forming the northern rim of the Ring of Fire, is the Aleutian trench shown here:

The Pacific plate descends into the mantle at the site of the Aleutian trench. Subduction zone volcanism here has generated the Aleutian island chain of active volcanoes. Courtesy of NOAA.

The crustal portion of the subducting slab contains a significant amount of surface water, as well as water contained in hydrated minerals within the seafloor basalt. As the subducting slab descends to greater and greater depths, it progressively encounters greater temperatures and greater pressures which cause the slab to release water into the mantle wedge overlying the descending plate. Water has the effect of lowering the melting temperature of the mantle, thus causing it to melt. The magma produced by this mechanism varies from basalt to andesite in composition. It rises upward to produce a linear belt of volcanoes parallel to the oceanic trench, as exemplified in the above image of the Aleutian Island chain. The chain of volcanoes is called an island arc. If the oceanic lithosphere subducts beneath an adjacent plate of continental lithosphere, then a similar belt of volcanoes will be generated on continental crust. This belt is then called a volcanic arc, examples of which include the Cascade volcanic arc of the U.S. Pacific northwest, and the Andes volcanic arc of South America.

Island arc formed by oceanic-oceanic subduction	Volcanic arc formed by oceanic-continental subduction

LINK

Yes, it’s the water that’s drawn into the earth’s crust that causes volcanic eruptions following subduction type earthquakes, and these eruptions can occur immediately after an eruption or days, weeks, months, or even after one or two years. That said, we have to remember that Japan’s recent earthquake(s) was also a mega-thrust type earthquake and we should expect volcanic eruptions of some, possibly more than one, of Japan’s many volcanoes sometime in the near future. (It is unusual, but not unheard of to witness the simultaneous eruption of two or more volcanoes.) It is also noteworthy that some of the aftershocks of Japan’s 2011 “Great Quake” were magnitude 6-7, extremely powerful themselves. Yes, the Shinmoedake volcano in Japan did experience a minor eruption in Japan on March 13, 2011 – and scientists are not sure that this eruption was directly related to the March 11th quake.

The question we have to ask ourselves is just how much water was drawn into the earth’s crust during each of these quakes and what, if any, will be the effects on the global community if Japan experiences a volcanic eruption(s) directly related to their recent mega-thrust earthquake. We know that one volcanic eruption has already occurred, however, after said eruption there were several 6-7 magnitude “aftershocks” that also could have contributed to the volume of water drawn into the crust and no one can say whether or not more volcanic eruptions could be in store for a country that is already coping with the worst natural disaster in their history.

Finally, there is one more burning question that I’m posing to our readership and any Vulcanologist/Geophysicist that might care to comment on this article. We know that the public has not been fully apprised of the danger that the Fukushima nuclear power plant poses to the global community. In fact, we do know that the United States has attempted to minimize the actual threat that it poses to our own citizens and it’s my contention that in the interest of money, greed and the future of nuclear power plants being built in our own country – we have not been told that Americans may be experiencing levels of radiation that are wholly unacceptable!

Radiation risks from Fukushima ‘no longer negligible’

The risks associated with iodine-131 contamination in Europe are no longer “negligible,” according to CRIIRAD, a French research body on radioactivity. The NGO is advising pregnant women and infants against “risky behaviour,” such as consuming fresh milk or vegetables with large leaves.

In response to thousands of inquiries from citizens concerned about fallout from the Fukushima nuclear disaster in Europe, CRIIRAD has compiled an information package on the risks of radioactive iodine-131 contamination in Europe.

The document, published on 7 April, advises against consuming rainwater and says vulnerable groups such as children and pregnant or breastfeeding women should avoid consuming vegetables with large leaves, fresh milk and creamy cheese.

The risks related to prolonged contamination among vulnerable groups of the population can no longer be considered “negligible” and it is now necessary to avoid “risky behaviour,” CRIIRAD claimed.

However, the institute underlines that there is absolutely no need to lock oneself indoors or take iodine tablets.

CRIIRAD says its information note is not limited to the situation in France and is applicable to other European countries, as the level of air contamination is currently the same in Belgium, Germany, Italy and Switzerland, for instance.

Data for the west coast of the United States, which received the Fukushima radioactive fallout 6-10 days before France, reveals that levels of radioactive iodine-131 concentration are 8-10 times higher there, the institute says. MUCH MORE

Please note that the above article was written on April the 11th, and finding updated information has been extremely hard. In the comment section of the story I linked to on the Fukushima nuclear power plant, “lottakatz” provided this information:

“The best place for radiation projections over Europe and the US was the Norwegian Institute for Air Research (NILU) but a couple of weeks ago they stopped posting the data and maps and scrubbed their site of the archived images. They don’t seem to be in that business anymore. At whose request or demand, one might wonder? Some of those maps were scary to say the least.”  LINK

I did research whether or not this comment was correct – and it was! (We need to demand that our own government provide it’s citizens with honest data and information on what we should eat, or not eat, whether rainwater has contaminated our crops, and what the overall health risks are to the general population.) For detailed information please read this excellent article and a re-posting of the NILU data:

Secret NILU Radiation Charts, North America

Here’s the question for a Vulcanologist/Geophysicist to answer; Based on several articles I’ve read, some which are linked to herein, there is an extreme danger that one of the reactors at the Fukushima nuclear power plant could (or already has) experienced a complete meltdown. The fault lines and convergence of the tectonic plates in Japan is very complex, possibly the most intricate on the planet. If they have or do experience a complete meltdown and it contaminates groundwater/seawater (remember, it’s right on the coast of Japan) without causing an extremely powerful explosion – could radioactivity be present in a subsequent volcanic eruption? The science of a complete meltdown, to the best of my knowledge and belief is wholly theoretical, as one has never occurred in the history of nuclear power plants – so one cannot state with certainty that when the melting fuel hits groundwater an explosion will reach the surface, or even that an explosion will occur.  That said, is there a risk of nuclear contamination worse than what we have so far experienced if a volcanic event happens after a nuclear meltdown – and could a complete meltdown cause even more deadly earthquakes in Japan as it enters the groundwater at different levels which could significantly affect the pressure on the very faults that caused Japan’s most recent spate of earthquakes????

Editor’s Note:

The 2010 Great Great of the coast of Chile was an 8.8 on the moment magnitude scale – which was obviously huge. A mega-thrust quake of this magnitude (The quake ripped the subduction zone for 430 miles) has the potential of drawing a huge amount of seawater into the earth’s crust which could have caused the “gash into the surface of the earth 6 miles long by 3 miles wide” due to the enormous amount of strain that so much water and the subsequent amount of pressure this water would cause as it instantly turned to steam as it reached depths that are extremely hot.  I do not find it “strange” that earthquakes have been rattling the area 45 to 50 miles away – But do believe that this could be an indication of more volcanic eruptions to follow. When you consider that Japan’s quake was a 9.0 on the moment magnitude scale, which is considerably stronger, it is not beyond anyone’s imagination that understands these quakes to believe that Japan and the global community could be affected by what could be a spate of volcanic eruptions that may occur in Japan sometime in the near future. Let’s hope I’m wrong…