Mw9.0 earthquake hits Japan, causes Tsunami (updated – 3)

An earthquake with a magnitude of Mw9.0 has occured 130 km east of Honshu, Japan in a depth of ~25 km. This had been the fourth or fifth strongest earthquake to be recorded by instrumental seismology. The quake caused significant destruction to the Honshu Island and triggered a tsunami that  destroyed a number of harbours. In some places (Sendai), tsunami heights were reported to exceed 10 m. A tsunami warning has been released for wide parts of the Pacific, but in Hawaii only 1 m was observed, therefore the warnings for the US West Coast have been lowered.

The tsunami warning has now been cancelled. The waves were observed all around the Pacific with wave heights of around 1 – 1.4 m in Hawaii and similar numbers at the US West Coast. Crescent City, however, was hit by a 2.4 m wave. Some damages have been reported, and one person is missing. Most of the Pacific Islands did not suffer waves higher that 1 m.

Honshu Island suffered peak ground accelerations of up to 0.25 g and intensities in the order of VIII (instrumental intensity). Aerial images show devastated land and a huge tsunami wave hitting the coast. Rockfalls and landslides have been caused according to Al-Jazeera and Boston imagery and ground cracks occured widely. Liquefaction appeared as well as slope failure and differential ground settling. Nuclear power plants have been shut down and three meltdowns were reported after four explosions in Fukushima. An Oil refinery was under fire and fires were reported from all over northern Honshu as well as from Tokyo. A good video collection can be found here. The best pictures are as always to be found at Boston.com.

Until now no final information on victims has been confirmed. Japan officials report about 3000 dead and 20000 missing. Yet it’s clear that damages will sum up to hundreds of billions of dollars, causing significant irritation on global stock markets.

Video showing the tsunami to flood Sendai Airport (by Russia today):

USGS has provided a moment tensor solution that clearly shows a subduction event:

The Finite Fault Model provides a 195/14 direction, with up to 17 m of maximum displacement:

This is just incredible. Here’s the USGS surface projection of the slip distribution:

USGS shake map:

Tsunami warning issued by the Japan Meteorological Agency:

Predicted wave heights, map from West Coast and Alaska Tsunami Warning Center:

On 9 March a series of pre-shocks began with an Mw7.2 event only 40 km away from the location of the Mw9.0 event. More events with magnitudes up to M6 followed, three of them at the same day. Most scientists thought that the 7.2 EQ had been the main event followed by aftershocks, but obviously the highest amount of stress has not been released.

Aftershocks map from EMSC:


The Collm seismological observatory of Leipzig University provides live access to their seismograms. Here’s the daily plot from 11 March. The observatory is part of the German Regional Seismological Network and located east of Leipzig. The Geophysical Institute of Leipzig University started instrumental seismology in 1902 and has a complete record since 1923! In 1935, the observatory moved from Leipzig to the Collm because of the increase of anthropogenic noise.

Japan is situated at the Pacific-Eurasia plate boundary, regularly experiencing strong earthquakes. Japan’s population is maybe the best-trained world wide in terms of behaviour during an earthquake and the risks of tsunamis. Seismic building codes count as the strictest world wide. The USGS database lists a huge number of strong events for the last 100 years:

(Data from USGS)

There is a large number of paleoseismological studies from Japan (mainly in Japanese), among them Ishibashi & Satake, 1998, Rikitake, 1998, Okumura, 2001, Yamazaki et al., 2002, and Okamura et al., 2005. Barnes, 2010 deals with Archeoseismology in Japan, Ishibashi, 2004 provides an overview on historical seismology. Tsunami deposits are among others discussed by Nishimura & Miyaji, 1995, Nanayama et al., 2000, Minoura et al., 2001 (see below) and Goto et al., 2010.

Strongest earthquakes since 1900 (from IRIS):

A great graphic from IRIS shows the relative energy released by earthquakes since instrumental seismology (read the comment of Jody below for understanding why this is very important):

Image by The IRIS Consortium

Ground truth trekking has a great article on that topic, too. I can really recommend to read it here.

Another great graphic by the USGS on strong earthquakes and the seismic moment (thanks to Jody):

Jody from Paleotsunami Travels has quite exciting articles on the Japan event on her blog. She kindly allowed to publish two articles on a paleotsunamis, that occured at the same coast like the 2011 one, but 1150 years ago:

Tsunami source of the unusual AD 869 earthquake off Miyagi, Japan, inferred
from tsunami deposits and numerical simulation of inundation

Satake, K.; Sawai, Y.; Shishikura, M.; Okamura, Y.; Namegaya, Y.; Yamaki, S.
American Geophysical Union, Fall Meeting 2007, abstract #T31G-03

The 869 Jogan earthquake, off Miyagi, produced unusually large tsunamis,
according to a historical document and tsunami deposits. One of the oldest
official documents in Japan reported that about 1,000 people were drowned
from the tsunami in Sendai plain, indicating much larger tsunami than the
1896 Sanriku tsunami (the worst tsunami disaster in Japan caused by a
tsunami earthquakes) or the 1933 Sanriku tsunami (caused by the outer-rise
normal fault event). Our systematic field surveys revealed the distribution
of tsunami deposits in Sendai and Ishinomaki plains. In both plains, the 869
tsunami deposits are identified as sand layers just below the regional
tephra (To-A from Towada volcano in AD 915). In Sendai plain, the tsunami
deposits extend about 1 to 3 km from the coast line at that time, which is
estimated as about 1 km inland of the present coast. In Ishinomaki plain,
the tsunami deposits extend > 3 km from the estimated coast line, which is
about 1-1.5 km inland of the present coast. Multiple sand layers indicate
recurrence of such unusual tsunamis with approximately 1,000 yr interval. We
computed tsunami inundation in both plains from several types of tsunami
source models such as outer-rise normal fault, tsunami earthquakes (narrow
fault near trench axis), interplate earthquakes with fault widths of 50 and
100 km. Comparison of the computed inundation area with the distribution of
tsunami deposits indicates that only an interplate earthquake source with
100 km width (depth range of 20 to 50 km) can reproduce the observed
distribution of tsunami deposits in both Sendai and Ishinomaki plains. This
source (Mw=8.1 to 8.3) is much larger than the anticipated Miyagi-oki
earthquake (M~7.5) with 99% probability in the next 30 year.

The 860 Jogan tsunami deposit and recurrence interval of large-scale tsunami on the Pacific coast of northeast Japan

Minoura, K., Imamura, F., Sugawara, D., Kono, Y. & Iwashita, T. (2001)

Read article here: Article (PDF)

Tsunami source of the unusual AD 869 earthquake off Miyagi, Japan, inferred

from tsunami deposits and numerical simulation of inundation

Satake, K.; Sawai, Y.; Shishikura, M.; Okamura, Y.; Namegaya, Y.; Yamaki, S.

American Geophysical Union, Fall Meeting 2007, abstract #T31G-03

The 869 Jogan earthquake, off Miyagi, produced unusually large tsunamis,

according to a historical document and tsunami deposits. One of the oldest

official documents in Japan reported that about 1,000 people were drowned

from the tsunami in Sendai plain, indicating much larger tsunami than the

1896 Sanriku tsunami (the worst tsunami disaster in Japan caused by a

tsunami earthquakes) or the 1933 Sanriku tsunami (caused by the outer-rise

normal fault event). Our systematic field surveys revealed the distribution

of tsunami deposits in Sendai and Ishinomaki plains. In both plains, the 869

tsunami deposits are identified as sand layers just below the regional

tephra (To-A from Towada volcano in AD 915). In Sendai plain, the tsunami

deposits extend about 1 to 3 km from the coast line at that time, which is

estimated as about 1 km inland of the present coast. In Ishinomaki plain,

the tsunami deposits extend > 3 km from the estimated coast line, which is

about 1-1.5 km inland of the present coast. Multiple sand layers indicate

recurrence of such unusual tsunamis with approximately 1,000 yr interval. We

computed tsunami inundation in both plains from several types of tsunami

source models such as outer-rise normal fault, tsunami earthquakes (narrow

fault near trench axis), interplate earthquakes with fault widths of 50 and

100 km. Comparison of the computed inundation area with the distribution of

tsunami deposits indicates that only an interplate earthquake source with

100 km width (depth range of 20 to 50 km) can reproduce the observed

distribution of tsunami deposits in both Sendai and Ishinomaki plains. This

source (Mw=8.1 to 8.3) is much larger than the anticipated Miyagi-oki

earthquake (M~~7.5) with 99% probability in the next 30 year.

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Christoph Grützner

works at the Institute of Geological Sciences, Jena University. He likes Central Asia and the Mediterranean and looks for ancient earthquakes.

See all posts Christoph Grützner

12 Comments

  • Andrew, student, Saint-Petersburg | March 11, 2011|20:09 (UTC)

    It is a huge tragedy, I hope everybody can survive in Japan. I know, it is a dream, but I want to believe. My english is not very well, excuse me. I have a quastion: is there a some correlation between Earth’s seismic activity and Earth’s position in an orbit at Solar system? You know, March, 21st – it’s a day of a spring equinox, in winter gravitational pressure Sun-Earth is most powerful, orbital speed on maximum. Can dynamical postion of Earth-Sun-Jupiter-Saturn create some preconditions for this situation?

  • Christoph Grützner | March 12, 2011|07:23 (UTC)

    Dear Andrew,

    as far as I know, any attempt to prove a correlation between earthquakes and orbit/planet constellations failed. It is clear that there are additional forces depending on the positions of the moon and the other planets, but they seem not to be sufficient for increasing earthquake probability.
    There are attempts to correlate EQs to heavy rainfall events and low pressure weather conditions, but the statistics behind that are quite difficult.

  • Andrew, student, Saint-Petersburg | March 12, 2011|12:15 (UTC)

    Thank you for the answer, Mr. Grützner. Your work and researches are very important and interesting. I hope, the paleoseismicity can help mankind to predict similar accidents much more earlier than in few hours in the future.
    Best regards.

  • Marie | March 12, 2011|18:07 (UTC)

    Dear Christoph,
    is there a direct connection to the recent EQ in New Zealand or do I have to dissociate one from the other? If there is a (tectonic) relationship, are more strong EQs somewhere along the Pacific continental plate expected in the near future?
    Thank you and best regards!
    Marie

  • Christoph Grützner | March 12, 2011|19:01 (UTC)

    Dear Marie,

    there should be no connection between the two earthquakes. They happened far away from each other and in a completely different geological setting. We know that earthquakes can trigger following events, but this requires them occuring at the same fault or at least within a certain system of faults. In my opinion the probability for large events somewhere around the Pacific plate did not increase. This is what statistics on historical data tell us and what we know from failure mechanisms. Of course there will be more strong aftershocks in Japan.

    All the best,

    Christoph

  • Marie | March 13, 2011|13:57 (UTC)

    Dear Christoph,

    Thank you very much for the prompt and informative answer!
    I hope you don’t mind me asking an other question.

    I have the impression, that there are more strong and devasting earthquakes around the world lately. E.g., on Christmas 2006 in Asia, last year in Haiti, now in Christchurch and Japan. Not to forget the earthquakes in Chile or China and so on.
    Is there more tectonic activity recorded than before? Or it is just more medial reporting on the events as more densely populated areas were/are concerned? Which – in the end – just gives the impression of an increase of earthquakes?
    Best whishes,
    Marie

  • Christoph Grützner | March 13, 2011|18:13 (UTC)

    Dear Marie,
    you are right, I think. It’s a mixture: media coverage plus many victims. There have been some very devastating and deadly events during the last decade:
    2003, Bam, M6.6: >31,000 dead
    2004, Sumatra, M9.1: 230,000 dead
    2005, Sumatra, M8.6: 1,300
    2005, Kashmir, M7,6: 86,000
    2006, Java, M6.3: 6,000
    2007, Sumatra, M8.5: 25
    2008, Sichuan, M7.9: 87,000
    2009, Sumatra, M7.5: 1,100
    2010, Haiti, M7.2: 300,000
    2010, Chile, M8.8: 500
    2010, Christchurch, M7.0: 0
    2011, Christchurch, M6.3: 160
    2011, Japan, M8.9: >10,000

    There are periods of lower and higher seismicity when we talk about large earthquakes. Magnitude 9 earthquakes do not occur very often. I have added a new image on that above. We had four really big ones within 7 years, 2 x Sumatra, Chile and Japan. This might be compared to the 60s and the time around 1900. The smaller the earthquakes are, the more equal is their statistical distribution over time. There is nothing special with the number of M6 and M7 events now. Okay, we have more M6 quakes because of the massive aftershocks, but that’s normal. As you can see from the data, most people did not die because of very strong events (2004 is of course an exception). They died because of bad luck and a low living standard. Bad luck means the earthquake occured at a location close to big cities or where it could trigger a tsunami. And then you have the building standards, maybe best illustrated by the Kashmir and Haiti events. In Chile the standards are high – an M8.8 event could have been far more deadly somewhere else. Look at this video of how the skyscrapers in Tokyo behaved during the quake. You also have to think about more people living close to coasts and in earthquake affected areas. In 1900 there were less than 2 billion people on Earth, now we are 7 billion…

    All the best, Christoph

  • vik | March 14, 2011|07:14 (UTC)

    Hi Christpher,

    I know you have said that there is no correlation with the salor system however After four years without any X-flares, the sun has produced two powerful blasts in less than one month: Feb. 15th and March 9th. This continues the recent trend of increasing solar activity associated with our sun’s regular 11-year cycle, and confirms that Solar Cycle 24 is indeed heating up, as solar experts have expected. Could this therefore have played a part? Could this be causing an increase on gravitaional “push” as oppossed to “pull”. Almost like a compresive force causing techtonic movement?

  • Christoph Grützner | March 14, 2011|17:38 (UTC)

    Dear Vic,
    to be honest, I do not know about the gravitation of a solar flare. I think we speak about a mass of some billions of tons. Sounds much, but isn’t compared to Earth (~6 x 10^24 kg), Moon (7 x 10^22 kg) and Sun (2 x 10^30 kg), so the gravitational effect will be low. There are stronger forces that affect the crust, like tides. In some places, body tides can be as high as 30 cm. They will for sure have a bigger effect. Even low pressure areas like hurricans will provide more additional force. I have never heard about a clear connection between solar activity and earthquakes.

    Best wishes,

    Christoph

  • Jody Bourgeois | March 15, 2011|07:39 (UTC)

    I just found your website, very informative. Nice job.
    I’ve been asked some of the same questions. For these very big events [I felt this one, I am in Sapporo, Japan; it lasted about 3 minutes shaking, like the earth was the ocean], the graph that IRIS has made can be a little misleading to the layperson, because the scale is logarithmic, and even an 8.2 added to an 8.8 still gives you an 8.8 — do you get what I mean? So if we plotted total energy, then there is REALLY a peak 1952-1964, then a big trough, and now another peak. We don’t have long enough records, though, to test the cyclicity statistically. Right now it seems pretty believable. Also, for these really big events, much and in many cases most of the damages and casualties are from the tsunami; if you watch videos of the tsunami approaching, you can see that most structures are still standing. Whereas shallow crustal earthquakes (like Haiti, Christchurch), when in populated areas, cause much more damaging shaking and destruction, even though they are MUCH smaller in terms of energy release.

  • Jody Bourgeois | March 16, 2011|01:46 (UTC)

    Thanks for adding that IRIS pie chart–very illuminating. Even if/when Chile 2010 and Japan 2011 are added, the picture will not change very much.

  • YASH PAUL KUNDAL | March 18, 2011|05:11 (UTC)

    The displacement of Japan to the east shows that it is always the overriding plate that plays the active role in the process of collision,therefore,accordingly the arrows marked on the Pacific plate showing the westward direction of movement should rather be marked on Eurasian plate to sow eastward displacement.It has become ample clear that plates lying along the concave side of arcs are the riding plates. The entire maps and books require a chage in making this point clear.——kundalyashpaul@yahoo.com

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