19 Feb 2012

That felt like a fairly large jolt

Feb 19, 2012 3:06pm
The earthquake that occurred just now felt pretty large. No damage here though.

Near Ibaraki it was a 5- on the Japanese scale of 7 by the epicenter. The earthquake info page is running slowly. Actual magnitude was just 5.1, but it was very shallow: < 10 km.

doug

Earthquake
15 Feb 2012

5 more earthquakes today bring the total past 1,800

Feb 15, 2012 11:19pm
Since last year's 3/11 earthquake there have now been more than 1,800 aftershocks greater than magnitude 4, including 5 today.

doug

1802
14 Feb 2012

That was a 6.2. What is it with these quakes today?

Feb 14, 2012 3:34pm
Just had another long, rolling one. No damage or anything like that. Just rocking doors and light fixtures in my house in Shinkoiwa. But it was larger than the one a few hours ago: magnitude 6.2. Again off of Ibaraki, but closer to Tokyo.
doug
14 Feb 2012

Magnitude 5.5 earthquake

Feb 14, 2012 12:55pm
That earthquake about 20 minutes ago was a magnitude 5.5. No damage. Nothing falling from shelves. But the rolling motion seemed to go on for a while. The center was off of Ibaraki.

M55
doug
11 Feb 2012

The earthquake just now was just magnitude 4.7, but it really shook my house!

Feb 11, 2012 10:39am
Here's the strength level map. On the Japanese scale it was a 3 out of a maximum scale in Tokyo. It looks like the epicenter was in southern Ibaraki, but as you can see very close to Tokyo.

doug

Earthquake
28 Jan 2012

Woken up by earthquakes

Jan 28, 2012 9:56am
I tried to sleep in this morning, but got woken up by earthquakes. Two were within a few minutes of each other and the 2nd one was especially strong in my house.

doug@9:55 am

Earthquakes
24 Jan 2012

New 'Big One' forecast: four years - Japan Times

Jan 24, 2012 9:52am
Kyodo

The risk of the southern Kanto region including Tokyo being hit by a major temblor within the next four years could be as high as about 70 percent, according to a study compiled by Monday by a team of researchers at the University of Tokyo's Earthquake Research Institute.

The figure is the same as the 70 percent forecast given for a magnitude 7.0 temblor hitting the region in the ambiguous "next 30 years" that has been repeatedly issued by the government's Headquarters for Earthquake Research Promotion on the basis of intervals between large quakes in the past.

Naoshi Hirata, a professor at the institute and a member of the team, said the risk of a big quake may have risen due to the 9.0-magnitude earthquake that hit in March 2011 off the Tohoku region, spawning tsunami that wiped out wide stretches of the coast.

Since the March disaster, seismic activity has been intensifying in the southern Kanto region and quakes with a magnitude of more than 3.0 have occurred about five times more frequently than in usual years.

1 Jan 2012

It was a magnitude 7.0!

Jan 1, 2012 2:50pm
It was a magnitude 7.0, but very deep (370 km). So on the Japanese "Shindo" scale of 0-7 it was only a 4 in Tokyo (see screenshot). I don't think there was any damage. A couple of things did fall from shelves though.

What a way to start the new year.

doug

Earthquake2012-1
1 Jan 2012

Big earthquake right now!

Jan 1, 2012 2:31pm
House still shaking…

doug

28 Dec 2011

Japan update - 1,700 earthquakes since 3/11

Dec 28, 2011 12:22am
As of today there have been 1,700 earthquakes of magnitude 4 or greater since 3/11.

Today there were three: magnitudes 4.6, 5.4 and 5.2. All were far enough from Tokyo that I didn't feel them.

The number of quakes has definitely gone done a lot since the big one hit in March. The daily energy release from earthquakes has also gone way down.

This graph shows the daily release in energy since 3/11.

Energyrelease
The red line shows the daily release of energy.

On March 11, an almost incomprehensible 2.1 EJ (2.1 quintillion joules) of energy was released in the 78 earthquakes that hit that day. By comparison, the energy released in the nuclear bomb used at Hiroshima released 63 trillion joules, so the energy released by the 3/11 earthquakes was over 30 thousand times as large. It was enough to slightly tilt the earth on its axis and shift the entire continent of Honshu.

Since the number of earthquakes have dropped greatly (yellow line) the daily release of energy has also fallen greatly. But even today, 12.4 trillion joules of energy was released in the three earthquakes. Fortunately that was distributed in 3 quakes in three different areas of the country and there was no reported damage.

doug

Doug Lerner's Posterous

I'm an American and permanent resident of Japan living in Tokyo. I also have a residence in St. Louis, and family in Boston.

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