Another earthquake has hit Japan, what is going on?

Is it too late to be an aftershock?

It is most likely an aftershock. Today’s was large compared to most activity, but not in relation to the big one 10 days ago.

Can we get some details on the numbers? Is it another 9 or something like a 6? I remember reading that larger 6–7 point aftershocks were expected in the following days.

How large was it? Japan has had daily aftershocks in the 6–6.5 range since the 9.0.

This map shows earthquakes around the world for the past 24 hours. Click on the icon for earthquakes (it’s to the right). You might find it interesting. I’ve looked at it daily since the big quake. I’m a map nerd.

Seismic activity does seem to be increasing.

CNN says it’s 6.5

@jlelandg It was 6.5, so you’re probably right about it being an aftershock. However, the thing that confuses me is that there were reports of two size 6 earthquakes a few days after the 9.0. If I can find the article that started that (it was BBC news so a reliable source) then I’ll share.

Can there be many aftershocks after a large earthquake? My friend who was there experienced a few small aftershocks (for lack of better word?) for an hour.

@Nullo It does. Although amusing to see people’s theories on the beginning of “2012” because of it.

Aftershocks can happen for quite a while, on the order of months.

@zenvelo I’ve heard they could last a year since the earthquake was so large. I’d like to say I’m glad I live in the Midwest, but I don’t live too far from the New Madrid fault line. Tornadoes and earthquakes. I’m screwed. lol

@jonsblond I’d rather be in an earthquake than a tornado or hurricane. You can build buildings to earthquake code. But a tornado? But I live in earthquake country so I’m used to them.

@Rarebear I lived on a concrete slab for the past 16 years. We finally live in a home now with a basement. You wouldn’t believe how much safer I feel now. Tornadoes are scary.

@jonsblond As a plus, the basement is typically cooler than the rest of the house in summertime, so you can save on the A/C.

@Nullo The downside, the basement is directly under our 16 year old’s bedroom. He likes to play drums on Rock Bank. It can be loud down there. ;)

@mazzkat, This article is quite informative. Aftershocks can go on for months afterwards.

@BarnacleBill Thank you kindly!

I think I heard that there can be up to 1,000 aftershocks after some quakes.

Here’s a seismic-activity monitoring map that shows global events over the last 5 years: http://www.iris.edu/seismon/

Aftershocks can continue to happen for a long time. I can’t find the stats but I’m pretty sure, as long as the 2nd (or 3rd, 4th, etc…) is smaller than the original large quake, it is considered an aftershock and these can happen for up to a year after the original quake. If there was an ‘aftershock’ that was larger than the 9.1 one that hit two weeksish ago, it would be considered the earthquake and the 9.1 would be considered a foreshock.

The aftershocks occur in a power law sequence. Because the original quake was so large, the aftershocks are also large. Because they are large, they are more noticeable.

I have a friend who lives about 50km from Tokyo, and he told me on Saturday that the aftershocks are still happening all the time, and that they’re still pretty powerful. He says that it’s gotten to the point where he’s almost used to them.

I agree with most and say its an aftershock although Im no USGS senior seismologist. A good enough comparison is the 1964 Alaska earthquake which maintains as the second strongest recorded quake ever, registering 9.2, or 2.5 gigatons equivalent. (2010 Sendai quake registered 9.0, or 476 megatons).. Point being in this analysis is that it took more than a year for the epicenter region around Anchorage to cease recording aftershocks.
As to whether this is a developing trend toward global annihilation, maybe.. 9.0 megathrusters average only about every 20 years, and Japan is already the second since the 2004 Indian Ocean quake/tsunami (mag ~9.1–9.3, deathtoll ~250K). <both Asiatic The other anomalous period of two plus 9.0’s would be the Alaska (1964) and the 9.5 magnitude 1960 Valdivia Chilean Earthquake (strongest recorded) <both Americas

According to http://en.wikipedia.org/wiki/Strongest_earthquakes#Largest_earthquakes_by_magnitude , one of the busiest periods for 8.5+ quakes was 1950–1965, when there were 7 quakes in that range.

The next 8.5+ quake after the the Rat Islands quake on February 4, 1965, occurred almost 40-years later.

So as of now, I don’t think that there’s necessarily going to be a continuously accelerating pattern of mega quakes

Pretty interesting, and the 8.8 Chilean quake last year may show a reemergence of heavy activity in the range. ..might not be most relevant picture, but i sinisterly found humor in “departamentos” 1 & 2 x’ed out.

@toaster – there’s a paper that seems relevant here.

Still very normal. In fact Japan was lucky that none of the aftershocks were 7.0 or more.

@the100thmonkey great article

i don’t now,

#2012