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H.-J. Ceccaldi et al. (eds.), Marine Productivity: Perturbations and Resilience of Socio-ecosystems,
DOI 10.1007/978-3-319-13878-7_6, © Springer International Publishing Switzerland 2015
Abstract
History repeats itself. In these 3,500 years, massive earthquake like the
Pacifi c coast of Tohoku earthquake in 2011 has occurred at least seven
times. Major earthquakes with big tsunami have occurred in 500- year
cycles along the Pacifi c coast of northern part of Japan. The tsunami
caused a lot of damage to the Tohoku region including marine life. During
the earthquake, wavelike movement observed on the surface of the tidal
fl ats. Liquefaction occurred just after the earthquake before tsunami.
Bivalves distributed inside the sediment were dug out to surface with a jet
of water. Not only the tsunami but also the liquefaction brought quick
damage in the coastal marine life. The earthquake caused sudden land
subsidence of about 1 m in maximum where intertidal zone became subtidal zone. It may take at least several 10 years to recover the coseismic
land subsidence. We have to clarify not only short-term effect which may
explain an initial recovery of intertidal and subtidal animals but also a
long-term effect which may explain continuous changes in mollusk population with land subsidence. Construction of tsunami seawalls has begun
without environmental assessment. Huge seawalls break the continuity of
nature to land from the sea. We have to clarify the impact on the coastal
ecosystem of artifi cial structures.
K. Okoshi (*)
Department of Environmental Science,
Faculty of Science , Toho University ,
2-2-1, Miyama , Funabashi , Chiba 274-8510 , Japan
e-mail: kenji.okoshi@env.sci.toho-u.ac.jp
Impact of Repeating Massive
Earthquakes on Intertidal Mollusk
Community in Japan
Kenji Okoshi
1
Introduction
At least seven magnitude 9-class earthquakes
have occurred along the Pacifi c coast from
Hokkaido to Tohoku over the past 3,500 years
(source: Sankei Shimbun , February 3, 2012), generating huge tsunami that inundated the coastline
after analyzing volcanic ash and sand layers in
H.-J. Ceccaldi et al. (eds.), Marine Productivity: Perturbations and Resilience of Socio-ecosystems,
DOI 10.1007/978-3-319-13878-7_6, © Springer International Publishing Switzerland 2015
Abstract
History repeats itself. In these 3,500 years, massive earthquake like the
Pacifi c coast of Tohoku earthquake in 2011 has occurred at least seven
times. Major earthquakes with big tsunami have occurred in 500- year
cycles along the Pacifi c coast of northern part of Japan. The tsunami
caused a lot of damage to the Tohoku region including marine life. During
the earthquake, wavelike movement observed on the surface of the tidal
fl ats. Liquefaction occurred just after the earthquake before tsunami.
Bivalves distributed inside the sediment were dug out to surface with a jet
of water. Not only the tsunami but also the liquefaction brought quick
damage in the coastal marine life. The earthquake caused sudden land
subsidence of about 1 m in maximum where intertidal zone became subtidal zone. It may take at least several 10 years to recover the coseismic
land subsidence. We have to clarify not only short-term effect which may
explain an initial recovery of intertidal and subtidal animals but also a
long-term effect which may explain continuous changes in mollusk population with land subsidence. Construction of tsunami seawalls has begun
without environmental assessment. Huge seawalls break the continuity of
nature to land from the sea. We have to clarify the impact on the coastal
ecosystem of artifi cial structures.
K. Okoshi (*)
Department of Environmental Science,
Faculty of Science , Toho University ,
2-2-1, Miyama , Funabashi , Chiba 274-8510 , Japan
e-mail: kenji.okoshi@env.sci.toho-u.ac.jp
Impact of Repeating Massive
Earthquakes on Intertidal Mollusk
Community in Japan
Kenji Okoshi
1
Introduction
At least seven magnitude 9-class earthquakes
have occurred along the Pacifi c coast from
Hokkaido to Tohoku over the past 3,500 years
(source: Sankei Shimbun , February 3, 2012), generating huge tsunami that inundated the coastline
after analyzing volcanic ash and sand layers in