Sensitivity Analysis of Relationship Between Tsunami Disaster and Coastal Embankment Structure

Abstract

An earthquake with a magnitude of 9.0 occurred off the Pacific Coast of Miyagi Prefecture, Japan on March 11th, 2011, accompanied by a devastating tsunami that caused severe damage to people and infrastructures. There have been many studies on the effects of coastal embankment, breakwater, as well as non-structural solutions such as pine trees, mangrove forest, and coastal dunes for reducing tsunami energy when it spreads to coastal areas. However, researches on sensitivity of coastal embankment structure in relation with tsunami disaster based on tsunami Shields number have not been widely carried out. Thus, the main objectives of this research are to investigate the sensitivity of coastal embankment structure in relation with tsunami disaster. In this study, a NEWFLUME model based on Reynolds Averaged Navier-Stokes (RANS) equations is applied to simulate the recent Great East Japan Earthquake and Tsunami 2011 along the coast of Suzaki. Results of numerical simulation have shown the reduction of tsunami Shields number in front of coastal embankment and landward area approximately 400 meter far from the backside of the embankment. In addition, estimated time of tsunami arrival was delayed due to the effect of various height of coastal embankment.

Shoreline Changes along Northern Ibaraki Coast after the Great East Japan Earthquake of 2011

“…(Tokyo Peil) data along the Ibaraki Coast, which is the area of interest of this study; the inundation height was approximately 19.5 m at the Sendai Plain in Miyagi Prefecture [4] (Figure 1). Many sea dikes and breakwaters along the coast were destroyed partially, or completely, due to the displacement caused by the earthquake and the tsunami [5].…”

“…The shoreline positions along these regions were rapidly changing in different ways due to the subsidence, relative sea level rise, and the tsunami associated with the earthquake. There were many locations along the coast where serious erosion and breaching of the barriers was observed [1,5]. Tanaka et al, (2016) analyzed aerial photos to quantify the sudden shoreline retreat along the Sendai coast that occurred after the earthquake of 11 March 2011.…”