Japan Quake Lifted Seabed 16 Stories—Largest Recorded

Giant slip may have spawned deadly tsunami, study says.

The tsunami-devastated town of Minamisanriku, Japan, is seen in November 2011. Photograph by Greg Baker, AP

Richard A. Lovett
for National Geographic News
Published December 1, 2011

Japan’s devastating March 11 earthquake shifted the seabed by as much as 165 feet (50 meters)—the largest slip yet recorded, a new study says.

That’s considerably larger than in previous reports, which in May put the shift at 79 feet (24 meters).

This giant movement probably caused the massive tsunami that killed more than 15,000 people and crippled the Fukushima Daiichi nuclear power plant (pictures).

For the study, Toshiya Fujiwara and colleagues at the Japan Agency for Marine-Earth Science and Technology compared seabed maps made in 1999 and 2004 to those made only days after the March quake.

Their analysis also revealed the seabed may also have risen by as much as 33 feet (10 meters).

“This is a very important piece of work, in some ways that may not be obvious at all,” said Chris Goldfinger, a marine geologist at Oregon State University who was not part of the study team.

The earthquake was the first in a subduction zone—a place where one tectonic plate is diving under another—in which scientists have been able to look directly at movement of pieces of Earth’s crust right up to the edge of the fault line.

Japan Quake Study at a “New Level”

Because subduction-zone earthquakes occur deep beneath the ocean, they are invisible from land.

In the past, scientists have had to deduce seabed shifts via seismic waves emitted by an earthquake. But that requires computer modeling, and the results can be frustratingly uncertain, Goldfinger said by email.

For example, the results may be specific to the model and are unable to capture the shifts at high resolution or with great accuracy.

But the new research, to be published tomorrow in the journal Science, will “open up a new level” in understanding how subduction zones behave and generate tsunamis, he said.

Before-and-After Quake Picture Not Perfect

Even so, the before-and-after pictures of the seabed shift aren’t perfect, Goldfinger cautioned.

The Japanese team’s original surveys were taken several years before the earthquake, and the “after” surveys were taken nearly two weeks later.

“The displacement [of the seabed] included everything that occurred between the surveys,” he said.

That includes not only the devastating earthquake but its aftershocks, as well as any less destructive “creeps”—or small movements—that might have occurred before the March temblor.

Still, it’s a major find, he said, because few subduction zones have been mapped well enough to allow such before-and-after images to be compared at all.

via Japan Quake Lifted Seabed 16 Stories—Largest Recorded.


Newly Discovered NEO Asteroid 2011 WP4 to Graze Earth on November 24, 2011

Posted by Chris Monty on November 21st 2011 

On Thanksgiving Day, you may want to give thanks for the fact that we (hopefully) haven’t all been smashed to bits.

NASA has just discovered a new Near-Earth Object (NEO), dubbed Asteroid 2011 WP4 which will graze our planet on Thanksgiving Day here in the U.S.

The asteroid was just discovered on Friday, November 18, 2011 and will pass by us at a distance of 0.0038 AU (Astronomical Units). 1 AU is equal to 150 million kilometers.

For comparison’s sake, Asteroid YU55, which just passed by us a few weeks ago, did so at a distance of 0.0022 AUs, so this one will be a bit farther out…but not by much.

The “Condition Code” assigned to this asteroid is an 8. Basically, orbit determination codes are rated on a scale of 1 to 9. A 1 means NASA is fairly certain of the object’s orbit and a 9 means they basically have no idea.

This asteroid was just discovered on Friday, so scientists have not had much time to analyze its path, which is why the uncertainty code listed is so high.

This is a fairly new find so there isn’t much data available on it at present.

“The 12 – 27 metre wide asteroid 2011 WP4 will make a close pass (1.5 lunar distances, 0.0038 AU), travelling at 10.84 km/second, to the Earth-Moon system on the 24th November, 2011 @ 08:13 UT ±00:42.”

Either way, it looks like it’s going to miss Earth, but it will likely be making headlines within the next day or two…and if the NASA experts are wrong, well, it will make for quite the Thanksgiving Day light show!

You can follow along and plot the asteroid’s path for yourself at NASA’s JPL lab here.

via Newly Discovered NEO Asteroid 2011 WP4 to Graze Earth on November 24 2011 (VIDEO).

Huge Sunspot on November 3rd, 2011 [Spawns X Class Solar Flare]

Nov 4, 2011; 8:54 AM ET

As I have recently talked about, the sun is entering its active phase. One of the largest sunspots in years is rotating over the sun’s northeastern limb. NASA’s Solar Dynamics Observatory took this picture of AR1339 during the early hours of Nov. 3rd.

An image of the sunspot named AR1339 Thursday night, Nov. 3rd, 2011

This sunspot will be turning toward Earth in the next 24 hours. We will have to watch very carefully and see if it affects the Earth in any way. This massive sunspot is over 25,000 miles wide and has already spawned a X Class solar flare.

This site will show you images of the sunspot as it turns toward the Earth: spaceweather.com.

My experts will keep you up-to-date on this developing situation. Please feel free to share your opinions!

I am always looking for subjects to write about and encourage you to share any pictures of anything astronomy-related.

via AccuWeather.com – Astronomy | Huge Sunspot (Named AR1339).