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Plenary Lecture
Towards the understanding of mega-thrust earthquake
occurrence system around southwestern Japan
-Developing and utilization of the dense ocean floor observatory-
Professor Yoshiyuki Kaneda
DONET group,
Japan Agency for Marine-Earth Science and Technology,
2-15 Natsushima-cho,Yokosuka,Kanagawa ,
237-0061 JAPAN
E-mail: kaneday@jamstec.go.jp
Abstract:
In Japanese seismogenic zone, the Nankai Trough around southwestern Japan is well known as the mega thrust earthquake generating large tsunamis, with the interval of 100-150 years.
In the 1944 Tonankai and the 1946 Nankai earthquakes, each hypocenter was located off the Kii peninsula ,southwestern Japan. Furthermore, according to the results of recurrence cycle simulation of mega- thrust earthquakes using precise crustal structure model, ruptures are starting from the Tonankai seismogenic zone ahead of the Nankai seismogenic zone. These results are consistent with past two earth quakes such as 1954 Ansei earthquake, 1944/1946 Showa earthquakes.
Therefore, the observation and research of the Tonankai seismogenic zone located in the center Nankai trough is very important and significant to understand the Nankai trough seismogenic zone system.
Especially, real-time monitoring of this seimogeniz zone is very important and powerful tool to understand the mega thrust earthquake occurrence system.
Therefore, we proposed and have been starting to deploy the dense ocean floor observatory network system around the Tonankai seismogenic zone since 2006.
This advanced dense ocean floor observatory network system has useful functions and purposes as follows,
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Redundancy, extendable and advanced maintenance system using the looped cable system, junction boxes and the ROV/AUV etc for long term observatory.
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Provide observed data such as ocean floor deformation derived from pressure gauges to improve the simulation and modeling researches about the mega-thrust earthquakes, this means the data assimilation, will be quite important to improve the simulation research.
These long term observatory data will give us valuable information about mega thrust earthquake seismogenic zone, such as ocean floor deformation, low frequency tremor and very low frequency
earthquake.
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Speedy evaluation and notification for earthquakes and tsunamis for disaster mitigation.
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Understanding of the interaction between the crust and upper mantle around subduction zone
using long term observation data.
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Developing advanced technology such as advanced ocean floor network system.
This system is equipped with 20 precise pressure gauges and 20 broad band seismometers and accelerometers. Therefore, reliable estimation of earthquakes and tsunamis will be expected.
In this paper, we will explain the advanced dense ocean floor observatory network system in detail.
and future collaboration with international network observatory groups.
Brief Biography of the speaker:
Yoshiyuki Kaneda has received a M.Sc degree in geophysics at Tokyo University,
As researchers of Physics geophysical exploration, Since 1979 he has been
working in the Institute of Japan National Oil Corporation (JNOC: JOGMEC in
now). He received Ph.D in 1995 at Tokyo University.
Since 1997, He has been invited as a program director of earthquake research
program to Japan Agency for Marine-Earth Science and Technology (JAMSTEC).
Now he has been developing the ocean floor network system for earthquakes and
tsunamis.
Main topics of his research are seismological structure and mega-thrust
earthquake recurrence simulation.
Prof. Kaneda won Awards of society exploration geophysics of Japan in 2001.
He has been a member of earthquake research committee of Japanese government
and evaluation committee of ESONET.
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