Earthquake in Japan in 2011: an eye-witness account
A severe earthquake occurred in Japan on March 11, 2011. The seismologist Prof. Tilmann from the GeoForschungsZentrum was on site. Here is his report:
This report was written on the morning of March 12, 2011 a short time after the earthquake, before both the the Fukushima nuclear disaster and the full number of tsunami victims were known. For reasons of authenticity the text, originally written in German, has not been changed, except for being translated into English. Both this article and the addendum written much later are a personal view.
When the earthquake occurred, some colleagues and I had been attending a workshop at the Atmosphere and Ocean Research Institute of the University of Tokyo, a building which had just recently been completed. We were listening to a lecture about the large earthquakes on Sumatra on the first floor of the building when we first felt a strong upwards and downwards movement (known to seismologists as P waves). As it started very slowly, it was not clear to us at first that it would be a large earthquake. However, after about 10 to 15 seconds we knew that it would be a large quake, and we quickly ran out of the building.
During the evacuation, horizontal movements (known to seismologists as S waves) set in, which were much more violent, but also had a very low frequency (slower movement). Movements of the structures within the building caused a metallic rattling.
When we had assembled outside, the earth made a rolling movement. The feeling was similar to being on a boat rolling with medium swell. This was then reinforced by the very strong shaking from the aftershocks, which at first could be felt almost every minute.
Some of the other people in the building needed very much longer to be evacuated, as they came from the higher floors. Fortunately no obvious damage occurred to the building. However, safety personnel advised to only re-enter the building for a short time at the most. After it became clear that no further personal danger existed, scientific curiosity initially prevailed among the geoscientists. However, we could then very quickly see the tsunami warning and the terrible pictures of the tsunami on the mobile phones of our Japanese colleagues, and we were of course shocked by the large number of victims which were already foreseeable.
Despite the considerable vibrations, no noticeable building damage or fires occurred in my immediate surroundings. Water, electricity and the Internet were available without interruptions. However, we were urged to save electricity (no hot showers!). There were no signs of panic, although in the city centre many Tokyo inhabitants were naturally faced with the problem of having to get home without trains. I have been in the hotel since yesterday evening, and despite the frequent shaking caused by the aftershocks the hotel seems to be running normally again.
Frequency of such events:
Events of such a magnitude occur on a global scale perhaps once every ten years on average, but we do not have instrumental seismological observations for a sufficiently long period to be able to give a reliable figure. However, the last seven years have been extraordinarily active with the magnitude 9.3 and 8.6 earthquakes on Sumatra in 2004 and 2005, and the magnitude 8.8 quake in Chile in February 2010. Before the Sumatra event in 2004, such quakes with magnitudes > 8.5 last occurred in the 1950s and 1960s (1950 Kamchatka, M=9.0, 1960 Chile, M=9.6, 1964 Alaska, M=9.2).
Preparation for the disaster and effects:
Despite the destruction in the coastal areas mainly caused by the tsunami it is therefore remarkable how well Tokyo weathered this earthquake. According to my information rail traffic was suspended only for safety reasons to examine the tracks, and a limited number of flights are already operating again.
Media reports stated that there were electricity supply problems in some parts of Tokyo; however, only an extremely small number of buildings collapsed.
The tsunami warnings were issued very quickly. Unfortunately, the time between the arrival of the tsunami and the earthquake was apparently also very short, and from the TV pictures it can be seen that the tsunami spread extensively into the country. Despite the dramatic images, colleagues reported that many people were rescued by “vertical evacuation”, in other words by fleeing onto special buildings designed for stability against tsunamis. Despite the almost optimum preparations taken by Japan, one must however understand that many large natural disasters will claim victims; this earthquake was the "Earthquake of the Century" for Japan. Nevertheless, I have no doubt that the Japanese preparations saved the lives of thousands, if not tens of thousands of people, and that such an earthquake in practically every other country in the world with a comparable population density would have resulted in many times more deaths. Every disaster naturally also represents an opportunity for learning how to be even better prepared next time. I presume that in the case of this earthquake this will in particular be a matter of avoiding fires in large industrial plants such as power stations and refineries.
Addendum (May 2, 2014):
More than three years have passed since the earthquake, and it clear that the assessment in the last section was overly positive and must be partially revised. With regard to the tsunami warning, it has since become known that the initially forecast and publicised tsunami heights wave were far too small. The sea walls in the cities on the east coast would have sufficed for the heights initially predicted, and according to anecdotal reports many people delayed evacuation from a false sense of security because of this. The underestimation of the tsunami heights resulted directly from the underestimation of the magnitude of the earthquake, a phenomenon typical of initial magnitude estimate.