Micro-tsunami from a local interplate earthquake detected by cabled offshore tsunami observation in northeastern Japan

A micro tsunami from an interplate earthquake (M-w 6.1) was observed in 199 8 on ocean bottom tsunami meters (OBTMs) deployed east off the northeastern Japan. The offshore tsunami data without complex distortions due to the co astal topography enable us to estimate reliable tsunami source parameters. The observed amplitude was about 1.5 cm at epicentral distance less than 10 0 km. We numerically computed the tsunami waveform by solving the linear Bo ussinesq equations. The observed tsunami waveforms are well explained by sy nthetic waveforms assuming the fault width of 10 - 15 km. The depth of the fault is estimated as 5 - 10 km below the seafloor, which is in good agreem ent with the location of the plate boundary defined by previous seismic stu dies.