To achieving this, a least square adjustment method was used to relate epicentral distance to topocentric displacements and the time of detection to epicentral distance. With the study of these two parameters, we aim to show their different behavior as the main shock propagates along the Japan islands, with a focus on a better understanding of the earthquake and its propagation. We also identified the time after the occurrence when the maximum displacements happen.
JMA ISPECTRUM DEFAULT IP SERIES
We studied the time series during the event setting up a threshold value at we consider the time series are being altered by the earthquake. By processing data from 93 GEONET reference stations, we analyze the 2011 Tohoku-Oki earthquake using PPP strategy. In order to surveille this activity, one of wider GPS network in the world was deployed, i.e., GEONET. Japan is located in the confluence of several tectonic plates, hence its seismicity. The advent of GPS provided a new way of measuring surface displacements due to earthquakes by deploying GPS networks within active seismic areas. Finally, a brief discussion on studying the countermeasures against ship motions triggered by seismic-induced harbor oscillations is presented. The effects of modal shapes of seismic-induced multi-mode harbor oscillations on the ship motions are analyzed. Notably, the ship's maximum displacement can be amplified remarkably when the periods of natural modes coincide with those of the forced modes.
The long-period ship motions consist of the natural modes of the mooring system and the forced modes relating to long-period harbor oscillations. Results reveal that seismic-induced harbor oscillations can trigger long-period movements of moored ships, consistent with the existing observations. In this article, the transient hydrodynamic characteristics of moored ships under seismic-induced harbor oscillations are investigated by a hybrid Boussinesq-panel model where the free-surface oscillations are modeled by a fully nonlinear Boussinesq wave model and are further used to drive the ship motions. Particularly, the hydrodynamic response of moored ships to seismic-induced harbor oscillations has not yet been studied. However, investigation of floating bodies under seismic-induced free-surface oscillations is rare.
The damage to moored ships and mooring systems will remarkably reduce their emergency capability to incoming tsunamis, probably further leading to property losses and casualties. These free-surface fluctuations could lead to damage in a wide range of forms, such as breakage of mooring systems due to excessive ship motions.
Free-surface oscillations induced by seismic waves were observed in many harbors.
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