E-mail updates
Follow on Twitter
Subscribe to RSS
AP Photo / Lee Jin-man
Hotel guests check their mobile phones for earthquake news after they evacuated the building following an aftershock, in Ichinoseki, Iwate Prefecture, Japan, Friday, April 8, 2011. Japan was rattled by a strong aftershock and tsunami warning Thursday night nearly a month after a devastating earthquake and tsunami flattened the northeastern coast.
The news today that Japan was hit by a magnitude 7.1 aftershock nearly a month after a magnitude 9.0 earthquake and tsunami devastated the northeast coast is grim, but not shocking to experts.
"It is not surprising as part of the aftershock sequence to see a magnitude 7 plus," John Bellini a geophysicist with the U.S. Geological Survey told me today.
Generally, he said, for each lower magnitude you expect to see ten times the preceding magnitude. So, in this case, experts expect to see one magnitude 8 earthquake, up to 10 magnitude 7s, and many, many 6s, 5s, and 4s.
Hundreds of aftershocks
Indeed, hundreds of aftershocks have hit Japan since the March 11 earthquake, but few have been above 7.0. According to the USGS, an aftershock about 30 minutes after the main shock was a 7.9. There has been one other greater than 7.0 aftershock and many smaller ones. An 8 is still possible.
"You can still have it," Bellini said, "but as time goes by it is less and less likely each day and we would expect to see fewer 7s and fewer 6s." In fact, he added, "we've been seeing a lot less aftershocks for the last week than two weeks ago."
John Rundle, an expert on earthquake dynamics at the University of California at Davis, said a large aftershock, especially near a major city such as Tokyo, was among his largest worries when we spoke about earthquake clustering last month.
More to come?
The 7.9 aftershock about 30 minutes after the main shock, which was about 100 kilometers from Tokyo, could have been the 8 he was worried about, he told me today, but he doesn't think the city is in the clear.
"Tokyo has had a lot of seismic activity in the last month," he said. "The thing I worry about is one of those events being significantly larger than the ones they've been having."
New to his list of worries based on probability analysis is the southwestern Japan town of Nagasaki, which he says "has an elevated probability for a magnitude 7 earthquake in the next 12 months or so because it's had two magnitude 7s in 1968 and since the last one it has had about 10 magnitude 6s. So it would be about for a magnitude 7."
More on Japan earthquakes:
- Is Japan's quake part of a cluster?
- Vast devastation, search for survivors after Japan quake
- Photoblog: How the quake shifted Japan
- Japan earthquake aftershocks
John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).
Leave a Comment:
If you haven't figured it out yet, they are probably going to have another big one in the next few days.
Get your cameras ready so you can further exploit their suffering! Oh wait.. that'd be unethical.
But they're exploitations have worked, haven't they? After all, you did read the article...
Of course, they will have more..........probably for years. We are still feeling aftershocks from last year's Easter Sunday quake in Guadalupe Victoria.
Dumbest story line ever. It's called plate tectonics. Look it up. It doesn't just go away.
It is a story to inform those people who don't know much about plate tectonics that high magnitude aftershocks are a normal part of the process. Not everybody knows about the topic. The article is an attempt at teaching them.
People learn from different sources. Articles like this help. They also provide backup information for those of us who know what is happening and who are trying to explain it to others.
'Dumb' would be ignoring the topic and letting conspiracy theory types claim that information is being withheld.
Yes, we're at 350+ aftershocks here in Tokyo and counting.
Heck those aftershocks aren't anything. Tokyo is still waiting for "the Big One" to hit. The 9.0 last month was not on the fault line that is overdue for a major quake.
Does a Bear live in the woods?
jim
That's $hit in the woods
The aftershock mentioned on March 11th that occurred at 15:15 local time was NOT a M7.9! it was a 7.4 which is about 16 times LESS powerful. On the Japanese shaking intensity scale, most places in and around Tokyo registered between a 4 and 5- (strong shaking but minimal damage). Prior to March 11th, Tokyo had a 26% chance of a major seismic event in the next 30 years (M 7.5 to M 8.3) - Because the M 9.0 transferred new stress to faults near Tokyo, my guess is the city will get hit with a M 8.0 class earthquake between now and May 2012 - the odds are about 20% of this happening. For years scientists in Japan have been saying there is a possibility of TWO M 8.0 class quakes hitting near or under the city within days of each other. (Faults ready to go are: Tokyo Bay, Tokyo Metro, Toukai) all these faults are over due. Toyko metro is 20 years over due... Toukai is 157 years)
If you take a close look at the aftershocks, you can see they are migrating closer to shore and moving south closer to Chiba, Ibaraki and Tokyo Bay. A major quake hit Shizuoka on March 15th at 22:31 local time and registered as a M 6.0 - Shizuoka is much closer to Tokyo and those dangerous faults (Suruga Bay included).
As of March 29th, there were 3x M7.0+ , 61 M6.0+ and 355 M5.0+ aftershocks. For a M9.0 class event, one would expect 2x 8.0+, 10x M7.0+, 100x M6.0+ and 1000 M5.0+ aftershocks within the days and months afterward. So we can expect a couple of 8s, a half dozen more 7s, about 40 more 6s and hundreds more 5s over the next few months.
It should also be noted that this quake has caused aftershock activity to be 3 times more active than would be expected after a large quake, yet we are not even half way through the cycle.
Anyone in Tokyo, Kantou, Tohoku regions need to be very careful over the next year. I warned friends and family days and weeks before the 9.0 event that an unprecedented event was going to occur within a week of me leaving Japan (it hit 36 hours after I left). Im really afraid that people in Tokyo will think things are finally settling down and then at that moment disaster will strike the city when it least expect it. The city is living on borrowed time... these cycles of seismic activity repeat themselves every 300+ years. The last round of mega quakes in the pacific was around 1700 and Mt Fuji erupted in 1707. Its FAR from over... its only begun.
Interesting comments. I'm curious whether you have some kind of scientific background in this area or are just an interested and informed layperson.
A combination of both. I have access to information and resources in Japan that american scientists would only dream of having. This and many years of research and some intuition play a part in my forecasts being generally accurate.
My scientific areas of interest include geology with special focus on earthquakes (being japanese) and astronomy.
A bit of an update for my comments back in April .. it appears what Ive been saying has now been confirmed by other scientists and is now appearing on Japanese news channels and documentaries. Near the epicenter of the March 11th event, there is a very high likelihood of a MAG 8.0 event occurring very soon ... which is in line with what I said about a minimum of 2 aftershocks in the 8 range. As well the Nankai troff (南海トラフ) is projected to have a quake registering at least a 9.0 on the richter scale which is on par with last years event. Furthermore, the odds of a earthquake occurring directly under tokyo (東京直下型地震) have increased from a 70% chance in 30 years to a 70% chance within 4 years according to official data. Over the past few days there has been quite a few moderate earthquakes near mount fuji (富士五胡) and there are signs that the mountain is waking up such as old hot springs coming to life, flooding from underground etc.
To summarize, we can expect at least THREE massive earthquakes with a minimum magnitude of 8.0 or higher with one being either directly under Tokyo or occurring within 50 km from the city. If these quakes occur relatively close together than its extremely likely that Mt Fuji will erupt within 60 days of those events. The timeline is fairly compact .. my guess is an aftershock of 8.0+ near the march 11 epicentre first, then the nankai event of 9.0+ second, then either tokai or tokyo with a magnitude of 7.5-8.5 third, plus at least one or two other major seismic events elsewhere in Japan followed by an eruption of Mt Fuji. Japan will be externally geologically active at least until 2014 or 2015 as indicated by past cycles.
Ive got updated stats on aftershocks as of April 7th - 4x M7.0 (Largest being 7.4) - 66x M6.0+ and 394x M5.0+ with 90 of those quakes registering on the Japanese intensity scale of 4-6+ (Strong to violent shaking, minor to moderate structural damage). the "Shindo" scale goes as high as 7 (more than 30% of building partially or completely destroyed).
As a point of referrence, a M7.0 releases 1000x more energy than a M5.0 event. This means that the M9.0 event of March 11th released 520x more energy than todays aftershock of 7.4 !! An a million times more energy than a M5.0 (considered a moderate quake).
A similar geological situation to that which is present along Japan’s east coast is found on the western margin of the United States and Canada along the Cascadia Subduction Zone. As shown here, the risk of a magnitude 8 to 9 earthquake over the next 30 years is substantial, not to mention the major risk of a massive earthquake along the San Andreas fault:
http://viableopposition.blogspot.com/2011/03/earthquakes-living-on-fault-line-and.html
Check my article on the readiness of the Pacific North West and it's relation to the Cascadia Subduction Zone, which starts at Mendocino CA and goes up to the top of Vancouver Island.
Mother nature does what she wants,when she wants and where she wants..nothing can stop that lady!
It's an awful thing to not be able to help people when they are in such a tragic situation. I pray all will be safe.
It's an awful thing to not be ale to help people when they are in such a tragic situation. I pray all will be safe.
It is really nice to see comments by people who have some experience in geology and obviously are educated in the processes currently happening below the crust. Thank you TFUTAKI and CATHY BERNARD. I would ask them and anyone else in a position to know, a question: is the fact that the moon has been closer to the earth than at anytime in the past eighteen years a contributing factor? We know the effects the moon has on the tides, might it be doing the same to the plates? The stress points were obviously building up and the pressure had to be released, perhaps the moon's effects caused that to happen sooner rather than later? It could have been worse. From Yokosuka, Japan -JJM
Hey jjmarold,
it is kinda hard to say, but it is more than possible, but most earthquakes are due to shock waves hitting the crust from the molten area between the crust and core of the earth. Magnetic flux can can the pattern of these shock waves and intensify them in theory, so you could very easily be correct!
All my life I have been hearing they are working on being able to predict earthquakes but so far there has not been one accurate one, We are in a position of being prepared or suffering the consequences. I do hope this a sign that things are stabilizing for a while tectonically speaking so they can get help to people and stabilize the nuclear plants. I hope we all learn from this that the crust of the earth in the long run is liquid and changes, most of the time slowly, but some of the time fast, very fast. The 1964 Alaska quake moved Texas an average of 4''! May the people of Japan recover and those that lost homes and businesses rebuild, those that lost loved ones find peace.
jjmarold...I believe that the moom has an influence on helping trigger earthquakes, but recent research is also noting that many major quakes are also happening, within days of major solar flare (sun spot) activity (impacting on magnosphere, which may be causing pressure points). So more likely to be a combination of sun/moon, than just the moon. There were major solar flares just days before the Christchurch Feb 22nd and Japan Mar 11th quakes.
It's very sad to hear that people don't take such things seriously, most people.
Wheather its a 7.4 earthquake or 9.0 earthquake, it's still devastating enough to cause damage, and fatigue among people. We should be right on their side and help, and put more money in helping then building personal things. Ever remember that they also helped us and other parts of the world?
I guess you have to be "an expert" to not consider a 7.1 shocking. I grew up in L.A., a 7.1 there would be considered more than shocking....... it would be a "holy sh**!!!"
It would have been shocking a month ago, but we've had more than 350 earthquakes in less than a month.
jjmarold - I believe that when the moon is at full moon and its closest approach in years that it will have a very minor impact on earthquake frequency. Billions of years ago the moon was 15x closer to earth than it is today, and in those times everyday would have tsunamis of 100 meters or more according to the latest research. The rule with gravity is 1/2 the distance equals 4x the gravitational pull. This is a rough calculation but the average distance from the moon to earth is 384,000 KM - we will call that G 1.00 if the moon was at 356,500 km like it was on March 19th - then the gravitational pull would be about 28% stronger that at its farthest point of 404,000 km - again these are very rough figures.
You also have to remember January 4th is call perihelion - this is when the earth is closest to the sun. The suns gravitational pull would be about 3-6% stronger than in July which is Aphelion.
Id say on March 11th the moon was at 387,489 KM away from earth (very near average distance). Therefore its unlikely the moon had any bearing on this earthquake occurring.
There are other factors too like variances in earths gravity depending on location. Gravity is much stronger on the Japanese islands compared to the deep trenches near the epicenter.
With earthquakes, many scientists can tell you roughly WHERE and with what probability an earthquake will happen. But even I was surprised that event came in at M9.0 - I was expecting near 8.4 seeing the largest one in recent history was an 8.2 in 1933 and another one hit （貞観地震/Jougan Quake) in 869 AD with a rough magnitude of 8.4 - prior to March 11th, a 9.0 mega-thrust event was considered very unlikely to occur in that area. We now know better. This truly was a "once in a thousand year event" for Japan.
IS JAPAN DUE FOR MORE AFTER SHOCK?
Really, really, this is your headline? My first reaction was to pass this by as stupid beyond all reason but instead I had to click on the story. Oh no, not to read it but to vent over that headline.
I get emails from the USGS ENS (United States Geological Survey Earthquake Notification Service). When the quake hit Japan there were a few smaller ones leading up to it, but dozens afterward. I now have 4.0 as my low threshold and now that the pressure has been dropped in Japan, Fiji, Papua New Guinea, New Ireland, New Britian, New Zealand, Kamchatka in Russia, a few in Alaska and one or two small ones in Oregon are shaking.
Baja California had two dozen in March. South America has had a few heading up to Guatemala and Honduras. The Rim of Fire is heating up.
Things are definitely heating up. We've had more SUPER QUAKES (8+) and volcanic activity, in the last decade, than see in any previous decade of the last century. Many faults (especially across the USA), are well overdue! Just make sure to be prepared, as best you can, because it's going to be BAD.
that ridge plate is on the move, hard to say when it will reach equilibrium again. Temporary as that may be. The moon may have some influence, but more a type of gravitational differential..albeit slight to trigger the plates to move...more so, I wonder if the moon quakes have increased this year. I don't so much believe the earth is having more quakes this year, the earth is always quaking some where, but I wonder if the total energy of ALL the quakes is greater, less or about the same...a kinda net energy loss or gain of the earth....yea if we were really good we would know the terrain all along the plates inner boundries and make some really good educated guesses and maybe even calculate the change in gravitational binding energy of the earth (a small factor of less than 3% that adds to earths mass)....there is so much to learn, but so much that we have already learned...there will be more quakes in the near future, I hope and pray japan only gets a handful of smaller ones for a while (at worst)...but those are only hopes and prayers and the facts we just don't know. I hope this quake has not damaged the reactors further.
Why havn't we heard of any further structural damage from these very large after-shocks?
There probably wasn't enough spectacular damage to report.
Yet! Apparently these large after-shocks are to continue for a few more months. Lets hope the media has their cameras in position.
IS JAPAN DUE FOR MORE AFTER SHOCKS?
Was the original title... nice change. *snicker*
Its okay dear writer, we understand you probably have a material quota to maintain or some such. Thus is problem with corporate media, You'll never see them just come on and be like; "The world is boring today, so there's no news! Here's some nice nature pictures instead!
why is the information about a strong aftershock not mentioned on any news reports. what is being kept from the public?? would like to be honestly informed, this is the most deadly material ( man made substance ) on the planet. 7.1 magnitude ( is not an aftershock ) it is an event when coupled with the damaged reactors that should be reported. why the hush??
Mr. Scapone: There was no hush about the 7.1 aftershock/earthquake. Information about it (and the more than 350 or earthquakes we've had in the last month) was extensively reported on in the Japanese media. Within hours or less--the 7.1 aftershock happened at about 11:30 PM, and I didn't check the news until 4:30 AM the following morning--information on what had happened at all of the nuclear reactors (not only the Dai-Ichi reactor) and the three coal-fueled power plants affected, had been mentioned.