miércoles, 16 de marzo de 2011

Terremoto y tsunami del Mega


Enviado por Gonzonet a través de Google Reader:


vía Dark Roasted Blend de Avi Abrams el 16/03/11

Link - article by Avi Abrams

Help Japan now. Donate at Google's Crisis Response Center.

We've briefly touched on this topic in Future Plate Tectonics, yet with another huge wake-up call earthquake (and continuing swarm of smaller quakes) in Japan, we feel we should cover this kind of apocalyptic natural disasters more broadly, as well as raise awareness about horrific conditions for people in North Japan right now.

(a house drifts the ocean after being swept away by tsunami, image via)

Thousands of people are left without shelter and means of transportation in the wake of combined earthquake/tsunami disaster - in freezing cold, with dwindling supplies (many stores display empty shelves, which is quite unusual sight for Japan). Please keep Northern Japan in your thoughts, and help by donating through a respectable company - Google - at this link.

(images via)

Earthquake in Japan was so strong (the fifth strongest since 1900) that it even sped up the Earth's rotation by 1.6 microseconds, causing a day to get slightly shorter - more info

And the earthquakes continue in this "Ring of Fire" zone. It almost became a non-event to feel 6.0 aftershocks in Japan today... However, remember that a 9.0 earthquake is 1000 times worse than a 6.0 scale earthquake - the Richter Scale is logarithmic.

(images via)


Historical Shakings

The great Alaska's quake and accompanying tsunami aftermath in 1964 (shown here is the 4th Avenue in Anchorage):

(images via)

The aftermath of the Great San Francisco Earthquake in 1906:

(photo via 1937 issue of LIFE Magazine)

Mega-size earthquakes usually happen when the ocean tectonic plate slips under the continent plate (in a process called "subduction") and catches there: the gradual movement of plates is then stopped (plates are locked together) and a huge amount of energy starts accumulating, resulting in a sudden release and a minimum 8.0 mega-quake.

(image via)

Here is an interesting graphic showing correlation between the motion of plates and releases of pressure, leading to major earthquakes:


Building codes are paramount

Compared to building standards in Japan, Canadian cities like Vancouver and Montreal (built on some of the most earthquake-prone areas in Canada) definitely have a problem. In case of similar disaster scenario, most of the older buildings will crumble... and newer buildings may not fare much better.

Even in modern Vancouver current building standards are only meant to withstand 6.0 earthquake, definitely not a 9.0 mega-quake. What's more, Vancouver airport and Richmond will be entirely covered by water in case of tsunami, making rescue operations difficult - source.

All these concerns are quite troubling, as the subduction zone near Vancouver Island is due to produce a mega-quake similar to Japanese one some time in the future - these quakes happen on average once in 300-500 years, and the last one was about 300 years ago, recorded by aboriginal tribes of Pacific Northwest.

Some photos of earthquakes in China, Afghanistan and Chile:

(images via)

Earthquake damage in Beichuan, China... see more here (warning: graphic images!) -

(image via)

The effects of ground "liquefaction", when the soil becomes almost fluid and bucks up in waves (you can see this effect spectacularly shown in the 2012 movie earthquake sequence):

(images via)


Roads Turning into Roller Coaster

Upswelling makes for a bumpy ride:

Going into the cracks after New Zealand earthquake in 2010:

(image via)

This road was "unzipped" by recent Japan earthquake (producing almost a meter of displacement):

(image via)

After 1995 earthquake in Kobe, Japan:

(image via)

Now this unique paving pattern was not caused by any earthquakes - but id did create an interesting urban landscape:

(original unknown)

Don't blame this on earthquake, either - this is a collapsed coal mine in Victoria, Australia:

(image via)


Tsunami is not over in an instant... it just keeps coming, and coming...

This is the strangest thing about this calamity: it just builds in in strength - at first the amount of water seems almost insignificant and comparable to river flood. But then more and more water arrives, and it gathers strength: consider that one cubic meter of water weighs 1,000 kilograms, or one tonne (a metric ton)! Such force is going to sweep everything in its path, making escape in a car or on a building rooftop quite questionable.

(simulation of a nightmare tsunami, from a Japanese movie)

There is never one single wave either. Helicopter footage clearly shows a row after row of deadly waves.

(images via)

Check out this huge maelstrom in the wake of tsunami... note how it dwarfs a boat near its center:

(image via)

See "before" and "after" aerial photos of the affected areas here. Also, perhaps the most harrowing videos of tsunami are collected on this page.


Yellowstone Time Bomb

Sometimes an earthquake swarm can signify a much worse development, like a full-scale eruption of volcano. The recent investigation into the earthquake swarms at Yellowstone - see here - paints a picture of magma chamber unrest and significant ground-swelling, which may or may not lead to a Supervolcano explosion in a few hundred years.

(image via)

Combined with the Cascadia Subduction Zone proximity, all this makes life in the American (and Canadian) Northwest very interesting.


Canine Earthquake Rescue Jacket

"Daschunds, the breed, was created to crawl through rabbit holes to chase out rabbits and groundhogs, but their size and shape makes them useful to crawl through rubble and collapsed buildings and locate victims... and bring them a small bit of food while they wait for rescuers to lift debris and rescue them"

(image via)





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