D., S. J. Duda and D. K. Chowdhury
(1996): P-wave magnitude spectra, stress drops, rupture complexities and other
source parameters from broadband seismograms of three 1987
Three large earthquakes in
Additional source parameters derived from the magnitude spectra are: asperity radius, displacement across the asperity, localized stress drop, and ambient faulting stress. Significant differences in the magnitude spectra and source parameters are observed between ER and SH on one side and WN on the other. The magnitude spectra of ER and SH are much simpler in shape, as compared to WN, which in turn is characterized by a high complexity and a low average stress drop (0.1 MPa). ER appears to be the result of a smooth and simple rupture with a homogeneous stress drop. SH reveals a moderate rupture complexity.
spectra, earthquake source parameters,
Density distribution and currents
generated by the surface and coastal buoyancy flux in a land-locked basin are
considered. A simple conceptual model is developed for the case when the
surface buoyancy loss (gain) is locally balanced by the coastal buoyancy gain
(loss). The model predicts cross-shore density gradient, coast-to-surface
directed hydraulic flow, and thermohaline circulation
characterized by upwelling (downwelling) along the
coasts and downwelling (upwelling) prevailing over
the greater part of the basin. Due to deflecting influence of the Coriolis force, long-shore currents appear as well, both barotropic (related to the hydraulic effect) and baroclinic (connected with the thermohaline
circulation). The model shows some similarity with the winter residual dynamics
Keywords: Seawater density, thermohaline circulation, quasigeostrophic flow, land-locked seas
A hydrostatic mesometeorological model APIKA (Vrhovec, 1991) was improved by a new turbulence parameterization using a complete prognostic equation for the turbulent kinetic energy with both horizontal and vertical advection of turbulent kinetic energy. Horizontal diffusion of momentum and heat by turbulence is explicitly included.
Three different forcing of temperature inversion layer dissipation in basins were studied: dissipation due to diabatic (thermal) forcing, dissipation due to the advection of colder air and dissipation due to wind shear. We show that in winter time the dissipation due to the cold air advection and dissipation due to increasing wind speed aloft are efficient enough to cause mixing of deep cold air lakes while irradiation thermal forcing at 45°N in deep basins is often insufficient to dissipate the inversion in deep basins when ground is cowered with snow.
Keywords: Numerical simulation, dry temperature inversions
The horizontal 1000 kg Wiechert seismograph has been calibrated on the basis of a comparison of its records to the ones that were obtained by the reference seismometer. The resulting magnification curve shows notable deviations from the theoretical one. Its most prominent feature is a sudden magnification increase observed for frequencies above 5 Hz, which is attributed to frame oscillations excited by the seismic waves. Also, the observed average response curve exhibits larger magnification for frequencies below the resonance frequency. The results indicate a non-linear behavior of the Wiechert instrument related to the degree of impulsiveness of the excitation.
Keywords: Seismograph calibration, historical instrumentation, Wiechert seismograph