Mechanisms for Damage and Failure from the Great East Japan Tsunami - Tohoku, Japan Earthquake and Tsunami of 2011 - page 47

Type of Damage or
Failure Mechanism

Location Structure Top of

Structure
Elev.
(m above
MSL))

Approxima
te Runup
Elev. (m
above MSL)

Fig.
#

Scour

Shizagawa Tsunami Wall +15.2 56

Arahama Beach Shoreline Dike +5 +12.2 57

Arahama Beach Restroom

Building

+5 +12.2 58

Natori Beach Shoreline Dike +5 +9 59

Otsuchi Tsunami Wall +5 +9 63

Taro Tsunami Wall 64

Kojirahama Tsunami Wall 65

Omoto Barrier Wall 66

Erosion

Rikuzentakata Beach & Seawall +19 68

Oya Beach &

Revetment

+15 69

Koizumihama
Beach

Beach & Seawall +19.6 70

Otsuchi Port & Tsunami

Wall

+8 71

Tanohata Road Abutment 72

Abutments End
Effects

Rikuzen Takada Road Abutment 73

Utatsu Bridge

Abutment

74

Fudai River Gate 75

Kojirahama Port Port

Infrastructure

+17.8 76

Subsidence

Kesennuma Port Port

Infrastructure

+8 77

Onagawa Port Port

Infrastructure

+18 78

Gamo Tidal Flats Tidal Flats +6.1 79

3.1 Tsunami Overtopping without Structural Failure
A number of the coastal structures withstood wave forces despite having been
overtopped. Structures can survive tsunami wave runup and overtopping if
(a) The structure's design capacity is not exceeded (shear stresses and/or bending
stresses within design limits of the structure's members)
(b) Adequate protection prevents landward or seaward scour
(c) Adequate protection deters turbulent and supercritical flows
(d) Impact loads do not damage the structure
(e) The structure can withstand buoyant uplift forces and lateral overturning
forces
(f) The structure has a significantly low profile such that the tsunami passes over
its top with little or no structural damage due to any resultant hydrodynamic
forces.