7.7 Earthquake In Siberia

Elaine Meinel Supkis

Another major quake, the earth continues to be unusually active after the Great Boxing Day Quake. The least active plate is the one sitting over the North Pole. For some reason, the plates surrounding the South Pole are all moving relentlessly north. I also wonder about the volcano arcs along the north and west rim of the Pacific Plate.

AP:

A major earthquake hit a distant, sparsely populated region of Russia's Far East early Friday, causing unknown damage and possible casualties, an emergency official said. The U.S. Geological Survey and Japan's Meteorological Agency estimated the quake's magnitude at 7.7.

The quake hit at around 12:30 p.m. local time in the Koryak region, nearly 4,350 miles east of Moscow and some 625 miles north of the largest city in the area Petropavlovsk-Kamchatsky, said Oleg Kotosanov, a duty officer with the regional emergency situations ministry.

Kotosanov told The Associated Press by telephone that there were reports of damage in some villages of the Pacific region, and that emergency officials were flying by helicopter to several locations. Federal emergency officials in Moscow said they had no information about the quake.

Russian news agencies said buildings had been damaged in the coastal village of Tilichiki, including a school, a hospital and an airport. The agencies said there were also some injuries.

Russia's north Pacific coast sits along a major tectonic plate and is frequently hit by earthquakes and volcanic eruptions.

Most of the time, if an earthquake doesn't hit a city, few bother to notice it. But just like the series of tremblors that hearlded the great quake a year and a half ago, these sorts of quakes are still important if one wishes to know what is going to happen next.

The plate that sits over the Arctic is the one that is moving the least. Indeed, for some reason we still don't fully understand, the general movement of the plates is mostly to the north. The continents are like in a college prank, trying to stuff themselves into a Volkswagen. The Mid Atlantic Ridge is forcing Europe and America apart, unlike the Pacific which is being relentlessly shoved against the Eurasian, North and South American plates.

It is interesting that the juncture where the Pacific Plate pushes against the slowest moving plate up at the Arctic has caused a long arc of volcanoes to form, the Aleutian Island chain. Here is a webpage that discusses the myster of why there are these strange looking volcano arcs, nearly all of which are in the ocean:

The Aleutian Arc abuts the Alaskan mainland behind a deep fiord penetrating the coast to the city of Anchorage. The arc is about 3200km long with approximately 100 volcanoes of which 40 are active giving rise to 170 eruptions in the last 100 years. Flying into Anchorage from Japan one passes one massive snow-covered volcano (to 2800m) after another, some at least emitting steam.

The fore-arc trench is up to 7000m deep, which, while less than the 10,000m of the Tonga Trench, is still a major geographic feature.

This poses a question. Why an arc? The old solution was that a flat shear plane intersects a globe along an arc sector, but a subducting section of oceanic crust is not a flat plate, it has the same curvature as the sector being underthrust? So an arc should follow a great circle. Something to ponder on.
Again we see some tendency for islands away from the continent and closest to Asia to be the least potassic, eg Piip seamount. The variation diagrams below illustrates what now seems to be the invariable wide range of K2O seen in a mature arc.

Scientists studying the chemical and mineral composition of these arc volcanoes see interesting patterns. What this means in the end is still evidently not totally understood. We have many assumptions about the lower levels of the earth but precious little hard data. One reason it pays off to study Mars' geology is, because it is now nearly a "dead" planet, it's past lies open to us to read since it isn't changing constantly. On the other hand, the urgency to study this planet, the most wonderful and important one in the universe, rises, doesn't it?

Yesterday's earthquake is still ongoing. 17 major tremblors in the last 24 hrs. 6.1 on down in severity. The first one was at 47 km deep. The "aftershocks" range from 10 km to 53 km deep. This is a major disturbance. It happened at the point where two volcano arc join. Sort of like this drawing of a traditional Romanesque arch. The event that triggered all this activity, down in Sumatra, was a great tearing in the crust whereas this event is a scrunching of the crust event. This is why California and the entire West Coast shouldn't be lackadaisical about their own situation. The Aleutian chain is responding to direct force. The complex tectonic actions which are at work in the North American west are less direct so it will probably be the last point on earth that will release the energy stored from sudden jerking of the earth last year.

The Mediterranean has been very busy this last week but nearly all the quakes were offshore so they were little noticed. Even the Mediterranean has a number of volcanoes! Indeed, several volcanoes are active, world-wide, it is as if they are whispering and sighing in unison, all of them are troubled in their slumbers and we wonder, which one will Mother Earth use to discharge her vast energy after she has been shrugging and tugging at her robes so much?

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Comments

[jsmith]

If you're going to have a 7.7 earthquake... a distant, sparsely populated region of Siberia is certainly a great place to have it! (Unless a yak falls on you. Then you're hosed.)

The next-to-last paragraph has an illustration. What is it an illustration of?

[Big Al]

The Earth has geology, Mars has areology.

[Elaine Meinel Supkis]

Architecture.

As for yurts or other tents falling: they don't hurt. Rock, cement or brick walls hurt. Japanese light houses caught on fire but they didn't crush like adobe which is the worst thing to be in during an earthquake.

[Elaine Meinel Supkis]

Yes, big Al!

And Venus has aphrodology! Sounds like a neat thing!