| 摘要 |
<p>PURPOSE:To permit estimation of the depth of hypocenter as well only with the information on the initial motion part at one observation point by measuring the oscillation waveforms of three components-vertical, zonal and meridional - and calculating the amplitude ratio V/H between the vertical and the horizontal oscillation components and also calculating the period, amplitude and max. value of V/H of the initial motion part successively. CONSTITUTION:The incoming of the seismic waves is monitored at all times by measuring the oscillation waveforms of the three components; vertical, zonal and meridional directions at one observation point and calculating the amplitude ratio V/H between the vertical and the horizontal oscillation components. Period, amplitude and the max. value of V/H in the initial motion part are calculated, upon incoming of the seismic waves. The hypocentral distance and the depth of hypocenter are then estimated from three sets of data. The accuracy is thereby improved even in the case of estimating the hypocentral distance of an earthquake having enough distance in excess of 200km. Since the depth of hypocenter is estimable at one observation point, the accuracy in outputting earthquake alarm is improved.</p> |
