Predicting earthquakes: The Mw9.0 Tohoku Earthquake and historical earthquakes in Northeastern Japan
Int. J. Disaster Risk Sci.
Predicting Earthquakes: The Mw9.0 Tohoku Earthquake and Historical Earthquakes in Northeastern Japan
Jifu Liu 1
Yongsheng Zhou 0
0 State Key Laboratory of Earthquake Dynamics, Institute of Geology , China Earthquake Administration, Beijing 100029 , China
1 State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University , Beijing 100875 , China
A magnitude 7.3 foreshock occurred two days before the magnitude 9.0 Tohoku Earthquake. The energy release of earthquakes within two days after the M7.3 earthquake is obviously different from the aftershocks of the Mw9.0 earthquake. But guided by historical earthquake experience, seismologists regarded the M7.3 earthquake as the main shock rather than a foreshock of another greater earthquake. Based on the analysis of historical earthquakes in coastal areas of northeastern Japan, the recurrence time of earthquakes is in quasi-periods of decadal or centennial scale. These quasi-periods are related to fault rupture along subduction zones located in marine environments adjacent to the coast. The probabilistic prediction for future earthquakes made by Japanese seismologists using historical earthquake data is based on a decadal scale quasi-period. It is difficult, however, to make relatively reliable predictions about the recurrence interval of rare great earthquakes based on historical earthquakes due to the very long intervals between large magnitude quakes and the limited historical and scientific records about their characteristics.
earthquake prediction; foreshock; historical earthquake; Japan; Tohoku Earthquake
1 Introduction
Short-range strong earthquake prediction according to a great
quantity of intensive small earthquakes is one of the common
methods employed in earthquake prediction, and the
prediction of the Haicheng Earthquake in China is the most
successful example (Chen 2009; Xu et al. 1982). But it is difficult to
tell whether an earthquake that has occurred is a foreshock of
another quake or is itself the main event. On the other hand,
due to a lack of foreshocks (Marzocchi and Zechar 2011),
no forecast was issued for the Tangshan and Wenchuan
Earthquakes, both of which resulted in considerable casualties.
On 11 March 2011, a Mw9.0 earthquake happened in the
northeast of Japan. Before this Mw9.0 earthquake, a M7.3
earthquake occurred on March 9 in the same place. The
M7.3 earthquake did not attract much attention due to its
occurrence under the sea over 130 km away from the shore.
In this location, the M7.3 quake caused neither severe
destruction nor a devastating tsunami, although the quake
belonged in the strong earthquake category in terms of
magnitude. By examining this earthquake and the subsequent
earthquake sequence, researchers later concluded that these
earthquakes were actually a foreshock sequence of a greater
earthquake rather than a typical aftershock sequence of the
M7.3 earthquake (He, Zhou, and Ma 2011; Ozawa et al.
2011). Why was the M7.3 earthquake not recognized earlier
as a foreshock? Seismologists attributed this to the lack of a
history of great earthquakes in northeastern Japan. Thus the
prediction of such an earthquake went beyond the cognitive
range of their seismic activities. Similarly, since no such
strong earthquake occurred in the Longmenshan area before
the Wenchuan Earthquake in China in 2008 (Wen et al. 2009),
seismologists took it for granted that there would be no
strong earthquake in the future in the area, and thus paid little
attention to its possible occurrence.
According to historical earthquake catalogues, earthquakes
have occurred periodically. In China, there have been five
active seismic periods since 1895, marked by the occurrence
of large earthquakes (Zhang, Fu, and Gui 2001). Period of
seismic activity is often used to predict the future trend of
earthquakes. Internationally, Geller and colleagues (1997)
and Sykes, Shaw, and Scholz (1999) hold somewhat opposite
views. According to the self-organized critical (SOC)
phenomenon, Geller and colleagues believe that earthquakes
cannot be predicted. But Sykes, Shaw, and Scholz think
that at a certain scale large earthquakes can be predicted.
Predicting the future trend of earthquakes according to the
quasi-period of historical earthquakes clearly involves great
uncertainties. In practice, prediction according to the
causative rules of historical earthquakes is one of the common
methods for predicting middle- and long-term earthquakes
(Wang 2009). But it is unavoidable for such a method to
fail in predicting great earthquakes with an especially long
causative cycle. This article discusses the limitations of
predicating earthquakes based on historical earthquakes by
analyzing the foreshock characteristics and historical record
of earthquakes in eastern Japan.
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2 Foreshock Activiti (...truncated)