Field observation at Kawasaki Koh Submerged Tunnel has been carried out since October 1979 to study the behavior of the submerged tunnel during earthquakes. Seven seismometers, ten bar stress transducers and six dynamic strainmeters are installed in the structure and the ambient ground (on the ground surface and in the bedrock). This paper describes the analyses of the data and the result of earthquake response calculations.
　The follwings are made clear by analyses and calculations.
a) The dynammic response of the tunnel depended on the properties of earthquakes. For instance, strains in the submerged tunnel are related to magnitudes and epicentral distances of earthquakes. Strain (ε) in Kawasaki Koh Submerged Tunnel is given in the following equation.
　log10ε/10-6=0.25M-1.36log10Δ-0.12
where M is magnitude of earthquake and Δ is epicentral distance. b) The wave propagation in the base rock and non-linear properties of the soil (rigidity and damping constant) are taken into consideration in the calculation model by mass-spring system. It is proved that dynamic responce of the tunnel and the ground fairly depends on velocities of wave propagation.
　This calcuation model may explain the characteristics of the strain in the submerged tunnel and the surface ground response obtained from the field observation.