1.
Narayan, J. P. (2001-2002): H/V ratio and
amplification factor: a numerical experiment using 2.5D modelling. Geofizika, 18-19, 1-16.
ABSTRACT:
This paper presents the H/V ratio peak
amplitude and frequency, their correlation with the site frequency and
amplification factor, and limitations. The basin-edge and flat-layer models
with different types of soils in the surficial layer were simulated using 2.5D
(two and half dimensional) modelling. The effects of sediment bedrock velocity
contrast on the H/V ratio peak frequency and amplitude, and the sensitivity of
the H/V ratio peak to both the S-wave transfer function and the ellipticity of
Rayleigh waves at the fundamental frequency were studied. Simulated results
revealed that H/V ratio peak frequencies for both the basin-edge and flat-layer
models were in good agreement with the soils fundamental frequencies, only when
velocity contrast was larger than 3.5. The comparison of H/V ratio peak amplitude
and amplification factors indicates that the use of amplitude of H/V ratio as
amplification factor of soil/site is not justified because the obtained H/V
ratio was not in accordance with the velocity contrast and can have any value
independent of soil velocity and was not similar in magnitude for radial and
transverse components. Analysis of the H/V ratio and spectral amplitudes of
responses of basin-edge and flat-layer models revealed that it was the trapping
of waves (body waves or surface waves) which was responsible for the spectral
peak in the H/V ratio at the fundamental frequency. It was also concluded that
surface waves were generated near the edge of the basin and propagated normal
to the edge, towards the basin. The peak amplification factors were found in
good agreement with the fundamental frequency of soil beneath respective
recording stations.
Keywords: H/V
Ration, amplification factor, 2.5D modelling, basin-edge effects and surface
wave generation
[PDF]
2.
Ivančić, I., D. Herak, S. Markušić, I.
Sović and M. Herak (2001-2002): Seismicity of Croatia in the period 1997
- 2001. Geofizika, 18-19, 17-29.
ABSTRACT:
During the
1997 - 2001 period seismic activity of Croatia was confined to the previously
identified seismically active areas. All together 1925 earthquakes were
located. Seismically the most active was the coastal part of Croatia,
especially its southernmost part where the Ston-Slano epicentral area exhibited
the continuation of the great earthquake sequence after the September 5, 1996
main shock. The strongest aftershock was recorded on April 26, 1997 at 07:30 (ML
= 4.5, Imax = VI °MSK). The earthquake
with the same magnitude ML = 4.5, recorded in the Zrmanja river
valley, near Obrovac, on November 9, 2000 at 03:01 (Imax
= VI °MSK). These two events were the strongest ones recorded in Croatia during the studied period.
Keywords: Seismicity,
[PDF]
3.
Bencetić
Klaić, Z. and T. Nitis (2001-2002): Application
of mesoscale model (MEMO) to the greater Zagreb area during summertime
anticyclonic weather conditions. Geofizika, 18-19, 31-43.
ABSTRACT:
A high-resolution insight in the flow patterns is necessary
for the study of various urban to regional scale phenomena. In this study the
applicability of nonhydrostatic mesoscale model MEMO (version 6) to the greater
Zagreb area under summertime anticyclonic weather conditions is evaluated. Results show that MEMO is able to simulate
mesoscale wind flow reasonably well. Simulated wind fields gave a detailed
illustration of the up- and down-slope circulation generated on south-facing
slopes of the Medvednica Mountain. However, daytime surface wind speeds seem to
be better predicted than the nighttime ones. Therefore, a further investigation
related to the choice of some of the input model parameters is needed.
Keywords: Mesoscale modeling,
[PDF]
4.
Supić, N., M. Orlić, D. Degobbis, T.
Đakovac, V. Krajcar and R. Precali (2001-2002): Occurrence of the Istrian
Coastal Countercurrent in 2000, a year with a mucilage event. Geofizika,
18-19, 45-57.
ABSTRACT:
The Istrian
Coastal Countercurrent (ICCC) appeared in March (7 cm/s), August and September
(4 cm/s) 2000, and a mucilage event occurred during late June-early July. Remarkably,
previous investigations indicated that recurrent occurrences of intense ICCC
coincided with mucilage and/or anoxia events in the region. In
fact, already during late winter, when a sea heat gain was relatively intense,
a significant transversal transport of freshened waters of Po origin occurred.
Lower salinity and warmer water pool, which might be the core of an
anticyclonic gyre in the northeastern Adriatic, was present also during spring
and summer. This indicates the establishment of a pronounced closed circulation
system in the area.
Keywords: northern Adriatic Sea, heat and water
surface fluxes, Po river runoff, geostrophic currents, mucilaginous aggregates
[PDF]