D. P. Kovalev

The tsunami on Sakhalin on August 2, 2007: Mareograph evidence and numerical simulation

Instrumental data on the tsunami registration on Sakhalin and Hokkaido islands are presented. The numerical simulation of the tsunami propagation in the Tatar Strait was performed. The results of the calculations are in satisfactory agreement with the observed data.

Synchronization of Long Ocean Waves by Coastal Relief on the Southeast Shelf of Sakhalin Island

The phenomenon of synchronization (trapping) of coming waves by the resonant water area in a coastal zone of the sea found from the observed data is considered in the paper. Edge waves with the period of about 10.7 minutes are visually observed in sea level fluctuations near the village of Okhotskoye and the cape Ostri on the southeast coast of Sakhalin Island. These waves are synchronized with the resonance water area. It becomes apparent from the unlimited increase of a phase between the bottom stations installed at distance of about 7.5km. In relation to the phenomenon found, the problem of weak and periodic impact on regular self-oscillatory system — Van der Paul’s oscillator — is considered. Good compliance between theoretical model and data of experiments is obtained.

Study of sea waves under the action of deep cyclones

Data from full-scale observations of the coastal zone during the passage of deep cyclones are analyzed. The time interval when three deep cyclones acted in the region of observations was chosen. The generation of long-wave processes during cyclones with different meteorological parameters and at different directions of approaching the shore was of interest. Data from the Management of Hydrometeorological Service were invoked for compiling maps of weather conditions, and meteorological data obtained from digital meteorological stations, as well as the spectral characteristics of oscillations of the hydrostatic pressure level at observational points, were analyzed. The frequencies of excitation of long-wave oscillations caused by cyclones were determined. Particular attention was paid to the range of periods of swell and wind waves. It was detected that swell waves are excited during the approach of cyclones at uncharacteristic frequencies with their subsequent displacement into their own frequency range.

Registration of the Simushir and Nevelsk tsunamis in the port of Kholmsk

AnalysisThe November 16, 2006, Simushir and August 2, 2007, Nevelsk tsunami records obtained by bottom pressure gauges in Kholmsk Bay are analyzed. The dominant role of the zero mode of eigen oscillations in the bay during the the wave field formation is shown: in the initial record interval (for the remote tsunami source) and 1.5 h after the first wave (for the nearly tsunami). Numerical modeling showed that the longer waves propagated toward Kholmsk in the case of the Nevelsk earthquake and they did not generate eigen oscillations of the bay. These oscillations were generated 1.5 h later when the shorter waves reflected from the Primorye coast arrived.