FIELD STUDY OF CONTRASTING BEACH RECOVERY PROCESSES OBSERVED IN NAMI-ITA and KIRIKIRI COASTS AFTER THE 2011 TOHOKU EARTHQUAKE

The 2011 Tohoku Earthquake caused significant shoreline retreat along the northern Pacific coast of Japan and most of the affected beaches have not yet fully recovered even six years after the event. This study investigates overall characteristics of the shoreline change after the event and also investigates contrasting beach recovery processes observed in Nami-ita and Kirikiri coasts.

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Site-Specific Behavior of 2011 Tohoku Earthquake Tsunami Influenced by Artificial Changes of Coastal Environments

Journal of Disaster Research ◽

10.20965/jdr.2012.p0485 ◽

2012 ◽

Vol 7 (sp) ◽

pp. 485-490

Author(s):

Chiharu Mizuki ◽

◽

Kazuomi Hirakawa ◽

Keyword(s):

Land Use ◽

Pacific Coast ◽

Tohoku Earthquake ◽

2011 Tohoku Earthquake ◽

Coastal Environments ◽

Specific Behavior ◽

The 2011 Tohoku Earthquake ◽

Site Specific ◽

The Pacific ◽

Artificial Changes

Many aspects affect local tsunami behavior. A drastic change in behavior in the 2011 Tohoku Earthquake at specific sites in relation to coastal conditions in Hokkaido. These include coastal constructions such as jetty ports, digging formula ports, types of seawall, etc., in addition to land use for fisheries. Examples of site-specific behavior in the 2011 Tohoku Earthquake along the Pacific coast of Hokkaido are introduced in order to help future tsunami disasters.

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Empirical Fragility Curves of Buildings in Northern Miyagi Prefecture During the 2011 off the Pacific Coast of Tohoku Earthquake

Journal of Disaster Research ◽

10.20965/jdr.2016.p1253 ◽

2016 ◽

Vol 11 (6) ◽

pp. 1253-1270 ◽

Cited By ~ 5

Author(s):

Hao Wu ◽

◽

Kazuaki Masaki ◽

Kojiro Irikura ◽

Susumu Kurahashi ◽

...

Keyword(s):

Pacific Coast ◽

Fragility Curves ◽

Ground Motions ◽

Strong Motion ◽

Tohoku Earthquake ◽

2011 Tohoku Earthquake ◽

The 2011 Tohoku Earthquake ◽

Kobe Earthquake ◽

The Pacific ◽

Miyagi Prefecture

In this study, empirical fragility curves expressed in terms of relationship between damage ratio indices of buildings and ground motion indices were developed in northern Miyagi prefecture located in near-field areas during the 2011 off the Pacific coast of Tohoku Earthquake. The ground motion indices were evaluated from observed ground motions at strong-motion stations and estimated at sites at which no strong-motion accelerometers were deployed during the mainshock. The ground motions at the non-instrumental sites were estimated using the empirical Green’s function method based on bedrock motions inverted from observed records on surfaces from small events that occurred inside the source fault, transfer functions due to underground velocity structures identified from microtremor H/V spectral ratios, and a short-period source model of the mainshock. The findings indicated that the empirical fragility curves as functions of Japan Meteorological Agency (JMA) instrumental seismic intensity during the 2011 Tohoku Earthquake almost corresponded to those during the 1995 Kobe Earthquake and the seven disastrous earthquakes that occurred between 2003 and 2008. However, the empirical fragility curves as functions of peak ground velocity were the lowest. A possible reason for this is that the response spectra of the ground motions in the period ranging from 1.0 s to 1.5 s were small during the 2011 Tohoku Earthquake. Another reason could be the seismic resistant capacities of buildings in the studied districts involved during the 2011 Tohoku Earthquake exceeded those in the cities affected during the 1995 Kobe Earthquake.

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