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could help researchers provide earlier warnings

During their study

scientists underwent a 50-day expedition on the Japanese drilling vessel Chikyu

They then drilled three holes in the Japan Trench area in order to study the rupture zone of the 2011 earthquake

a fault in the ocean floor where two of Earth's major tectonic plates meet deep beneath the surface of the Pacific Ocean.

The conventional view among geologists

has been that deep beneath the seafloor, where rocks are strong, movements of the plates can generate a lot of elastic rebound

Closer to the surface of the seafloor, where rocks are softer and less compressed, this rebound effect was thought to taper off

In fact

the largest displacement of plates before the 2011 tsunami occurred in 1960 off the coast of Chile

That's when a powerful earthquake displaced seafloor plates by an average of 20 meters

The Tohoku earthquake, in contrast, displaced its own plates by 30 to 50 meters.

So what caused this unexpectedly violent slip

the fault itself is very thin--less than five meters thick in the area sampled.

makes it the thinnest plate boundary on Earth.

In addition, clay deposits that fill the narrow fault are made of extremely fine sediment, which makes it extremely slippery

these findings don't just show researchers a bit more about the past; they also have implications for the future

Other subduction zones in the northwest Pacific where this type of clay is present--from Russia's Kamchatka peninsula to the Aleutian Islands--may also be capable of generating similar, huge earthquakes

This is part of the messy business of breaking up a plate. … This is a geologic process

will take millions of years to form a new plate boundary

likely, it will take thousands of similar large quakes for that to happen."

All four faults

were strike-slip faults, meaning ground on one side of the fault moves horizontally past ground on the other side

great quake of last April 11 "is possibly the largest strike-slip earthquake ever seismically recorded

although a similar size quake in Tibet in 1950 was of an unknown type

2012 quakes likely were triggered, at least in part, by changes in crustal stresses caused by the magnitude-9.1 Sumatra-Andaman earthquake of Dec. 26, 2004

the 8.7 and 8.2 quakes were generated by horizontal movements

not by vertical motion

explains why they didn't generate major tsunamis

8.7 quake caused small tsunamis, the largest of which measured about 12 inches in height at Meulaboh, Indonesia

Indo-Australian plate is breaking into two or perhaps three pieces

happening because it is colliding with Asia in the northwest, which slows down the western part of the plate, while the eastern part of the plate continues moving more easily by diving or "subducting" under the island of Sumatra to the northeast

subduction zone off Sumatra caused the catastrophic 2004 magnitude-9.1 quake and tsunami

ruptured along a roughly 90-mile length

seafloor on one side of the fault slipped about 100 feet past the seafloor on the fault's other side

second fault, which slipped about 25 feet, began to rupture 40 seconds after

extended an estimated 60 miles to 120 miles north-northeast to south-southwest – perpendicular to the first fault and crossing it.

third fault was parallel to the first fault and about 90 to the miles southwest

started breaking 70 seconds after the quake began

along a length of about 90 miles

slipped about 70 feet

The fourth fault paralleled the first and third faults

began to rupture 145 seconds after the quake began

fault rupture was roughly 30 miles to 60 miles long.

fault slipped about 20 feet past ground on the other side

a new study also points to a more earthbound culprit: the presence of a land bridge connecting Asia to North America.

debated whether the climate swings were driven by sharp variations in solar activity or simply by unstable climatic processes

Earth's climate has been relatively stable since the end of the last ice age

temperatures were fairly stable, too, after the ice age began in earnest about 100,000 years ago

20,000 years later, things became unhinged

global sea level dropped to about 50 meters lower than it is today

As the ice sheets that covered North America and northern Eurasia snatched up more and more of Earth's water

exposed a broad strip of land that connected what is today Alaska and Siberia

Ancient animals used the land bridge, which measured as much as 1500 kilometers wide in spots, to roam back and forth between Asia and North America

also huge consequences for Earth's climate

two sets of climate simulations

one in which the Bering Strait was open

one in which it was blocked

each set of simulations, the researchers gradually added large amounts of fresh water to the North Atlantic between the latitudes of 20° and 50

researchers propose, this swath, which spans the latitudes from southern Cuba to southern England, would have received large amounts of meltwater from Northern Hemisphere ice sheets during warm spells that occasionally punctuated the ice age

Today, the surface waters in this swath affect the temperature and salinity of water even farther north in the Atlantic

a region where surface waters cool, sink to the seafloor, and then flow southward—a critical link of the worldwide conveyor belt of ocean circulatio

Gulf Stream, which brings climate-warming waters from the equator to the North Atlantic, comes to a halt.

If waters of the far North Atlantic don't sink, says Hu, much of the large-scale ocean circulation worldwide temporarily collapses

surface waters became so fresh that they never got denser than the underlying salty water, and therefore never sank

shutting down ocean circulation and plunging areas around the North Atlantic, including Greenland, into a cold spell

researchers noted a critical difference between the sets of simulations: When the Bering Strait was closed, it took as many as 1400 years for ocean circulation to recover; when the strait was open, the circulation rarely took more than 400 years to recuperate

sign that ocean circulation is stable when the strait is open

Whenever the ocean circulation shut down in the simulations, temperatures in Greenland suddenly dropped by 12°C—a decrease similar in magnitude to many abrupt cold snaps chronicled in the Greenland ice core records

A team led by oceanographer

bounced sound waves off the deep-sea mountain to measure its size

Tamu Massif forms a broad, rounded dome rising 4 kilometers from the seafloor and stretching 450 by 650 kilometers across

Core samples that the researchers extracted from the volcano’s slopes showed that, during its prime 145 million years ago, the ancient mound spewed lava sheets 23 meters thick.

The fossils were discovered in 1909. Since then, several other fossil sites have been found in the Burgess Shale, but none as rich as the original.

The fossils are extraordinary because they preserve soft parts of ancient animals in exceptional detail

soft parts are less likely to be imprinted in stone than harder parts, like bones

More than 200 animal species have been identified at the 1909 fossil site

The new site is also in the Burgess Shale formation, and seems to rival the 1909 original in fossil diversity and preservation

In just two weeks, the research team collected more than 3,000 fossils representing 55 species. Fifteen of these species are new to science.

there is a high possibility that we'll eventually find more species here than at the original Yoho National Park site, and potentially more than from anywhere else in the world

The new fossils were spotted in a mountain cliff, in Marble Canyon, about 26 miles (42 kilometers) southeast of the original Burgess Shale site

The newly discovered rocks are probably about 100,000 years younger than those at the first Burgess Shale site

Many of the fossils at the new site are better preserved than their quarry counterparts

The new fossils reveal the internal organs of several different arthropods, the most common type of animal in both the new and old Burgess Shale locations.

Retinas, corneas, neural tissue, guts and even a possible heart and liver were found.

the first time we're seeing these details

About half of the 55 species discovered at Marble Canyon so far are also found at the original Burgess Shale site

Some of the original site's rare species are more abundant in the canyon

Some species at Marble Canyon are also found in China's Chengjiang fossil beds, which are 10 million years older than the Burgess Shale

Until now, researchers thought these Cambrian animals went extinct by the time the Burgess Shale formed.

Their discovery in Canada means that many Cambrian life forms were more widespread and longer-lived than previously thought

Located off Australia, China, North America and South Africa, the newly discovered fresh water reserves can be used to supply water to coastal cities

this water resource is a hundred times greater than the amount we've extracted from the Earth's sub-surface in the past century since 1900

groundwater scientists were very well aware of the presence of the freshwater reserves beneath the seafloor, but have assumed it to occur during unusual and extraordinary situations

this latest study reveals that the fresh and brackish aquifers under the seabed are a common phenomena

formed hundreds to thousands of years ago when the sea level was lower than what it is currently

rainwater penetrated into the ground and filled up the water tables in regions that are currently under sea

Nearly 20,000 years ago, the sea levels rose, the ice caps began melting and the areas were covered by oceans

Most of the aquifers today are protected from seawater by blankets of clay and sediments that are piled on top

These aquifers are not different from those found below land. Their salinity is low due to which they can be easily converted into drinking water

researchers propose two ways to gain access to these freshwater reserves

either be by constructing a platform and drilling into the seabed, which is expensive

Or drill from the mainland that is at a closer distance from the aquifer

Freshwater under the seabed is much less salty than seawater

it can be converted to drinking water with less energy than seawater desalination

also leave us with a lot less hyper-saline water

freshwater offshore should remember is that the water reserves are non-renewable and should be used carefully

disappeared from the fossil record around 540 million years ago, just around the time the Cambrian Explosion of evolutionary history

"Ediacaran fossils are extremely perplexing: they don't look like any animal that is alive today, and their interrelationships are very poorly understood," said Lucas V. Joel

Hemiscyllium halmahera, named after the eastern Indonesian island of Halmahera where it was found

Of all known

walking sharks, six of nine species hail from Indonesia

The animals lay eggs under coral ledges, after which the young sharks lead relatively sedentary lives until adulthood

These sharks do not cross areas of deep water and are found in isolated reefs