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111.
P. Špaček Z. Sýkorová J. Pazdírková J. Švancara J. Havíř 《Studia Geophysica et Geodaetica》2006,50(2):233-258
The Variscan Bohemian Massif is disrupted by the NW-SE striking Elbe Fault System in its northern part. The increased tectonic
activity associated with this structure is manifested by increased seismicity in the eastern part of the Sudetes. With the
use of a temporary local seismic network, the total number of micro-earthquakes located in this region increased to 153 for
the period 1996–2003. The local magnitudes vary between −0.6 and 1.8 and the seismic energy was often released in swarm-like
sequences. Five seismic events with well-defined P-onset polarities at five or six stations enabled the estimation of focal
mechanisms. The present-day activity of the WNW-ESE to NNW-SSE fault systems is discussed on the basis of source mechanisms,
the alignment of the epicentres, as well as morphological and geological evidence. The majority of the recent seismic activity
is concentrated in a 40–60 km wide zone of a generally NW-SE trend. This structure represents a regional zone of weakness
within the SE termination of the Elbe Fault System, defined by a mesh of interconnected faults, of which many are deep-seated
and highly permeable and some are associated with light to moderate historical earthquakes. Both in the areas due south and
due north of this zone the present-day seismic activity is very low. The increased tectonic activity can be interpreted as
a result of the abundance of suitably oriented faults and their interconnection into major fault systems, the proximity of
the Outer Carpathian indentor and the Cainozoic volcanic and associated recent post-volcanic activity. The similar character
of swarms and their coincidence with the post-volcanic activity in the southeastern part of the Elbe Fault System and in some
focal zones of the western Bohemian seismically active area suggests that overpressurized fluids may represent a potential
swarm-triggering mechanism. 相似文献
112.
113.
Summary Fresnel volumes and interface Fresnel zones of transmitted and head waves are studied. The relation derived for transmitted waves may also be used for converted reflected waves. Considerable attention is devoted to the penetration of Fresnel volumes across structural interfaces, particularly for head waves. 相似文献
114.
The reason why the synthetic amplitude distance curves of P-waves for models IASP91 and PREM, observed for shallow sources up to epicentral distance of 28°, oscillate is illustrated by means of synthetic seismograms. Furthermore the position of the beginning of the diffraction of the P-wave at the CMB, depending on the prevailing signal period, is discussed in connection with the extension of Fresnel volumes. 相似文献
115.
Summary We search for the effects of the interplanetary magnetic field (IMF) sector boundary crossing (SBC) in upper stratospheric ozone. The SBUV data (Nimbus-7) at the 10, 3 and 1 hPa levels are analysed for latitudes 45° N and 55° N for winters of the period December 1979 to December 1982. An effect of the IMF SBC wos only found at the 10 hPa level. These first results concerning the IMF SBC effect in upper stratospheric ozone are rather preliminary.
¶rt;m uu nu mau () nam aum n () a mam. SBUV ¶rt;a (u-7) a nm ¶rt;au 10, 3 u 1a aauum ¶rt; um 45° u 55° . . ua nu¶rt;a ¶rt;a 1979 – ¶rt;a 1982. m uu a¶rt; m a 10a. mu n mam n uuu a mam m n¶rt;aumu.相似文献
116.
Jaromír Janský Jan Zedník Vít Kárník Reviewer J. Vaněk 《Studia Geophysica et Geodaetica》1988,32(3):264-271
Summary The theoretical medium period PV-magnitude calibrating curves were computed for the Earth model PREM and a wide range of focal depths. The calculated set of curves reflects the distribution of model parameters, the influence of source radiation was not taken into account. The widely used Gutenberg's empirical calibrating curves were compared with the theoretical ones. Pronounced deviations in the shape and differences in the level of isolines were found. Thus, if model PREM is considered to be representative of the Earth's structure, the empirical calibrating curves (D, h) for magnitude determination currently used in seismological practice, have to be verified.
auma mmuu au u u ¶rt; n¶rt;u aum¶rt; - n ¶rt;nu¶rt; annaam ¶rt; ¶rt;u u RE u ¶rt;uanau aa. uu maam an¶rt;u naam ¶rt;u ma uu u umua. u nu nuuu au u ma u a mmuuu uu. u a¶rt; mu auu n u u. au a, u num ¶rt; RE n¶rt;maum ¶rt; mu u, m ¶rt;u num nuuu au u (D, h) ¶rt; n¶rt;u aum¶rt;, m am unm u namu.相似文献
117.
Jaroslav Kubík Reviewer A. Janáčková Reviewer V. Červený 《Studia Geophysica et Geodaetica》1988,32(3):287-299
Summary The dependence between Pn-wave velocities and the surface heat flow, temperature at the core-mantl boundary and thickness of the Earth's crust for continents (Europe, Asia, North America and Australia) was investigated statistically in connection with the problem of lateral inhomogeneities in the upper mantle. The relations obtained were compared with those determined under laboratory conditions. The conclusion is that temperature and pressure effects may provide additional explanations of the regional variations of Pn-wave velocities observed in most continents.
auum ¶rt;auu mu n¶rt; a nmu uua(Pn ), nm mn nm, mnam a u m mum a u¶rt;aa u n uuuma ¶rt;¶rt;m mu Pn. nua ¶rt;a mama aam u¶rt;au nu m n¶rt; amuu u u ¶rt;au u mnam a¶rt;um mmmuu mamau n¶rt;aa am. am ¶rt;, m ua uu m Pn- ¶rt; amu muma n¶rt;m auu m¶rt;uauu u a nmu muua.相似文献
118.
119.
Summary The ionospheric effects of the interplanetary magnetic field (IMF) sector boundary crossings are studied for the winters of 1963–69. They are considerably stronger for proton than for non-proton sector boundaries. There are two different types of effects. The geomagnetic type is a disturbance, observed in geomagnetic activity, the night-time ionosphere and the day-time F2 region near the geomagnetic equator. The effect in the ionosphere is interpreted in terms of the IMF sector boundary crossing related changes in geomagnetic activity. The tropospheric type is aquietening, observed in tropospheric vorticity and in the day-time mid-and low-latitude ionosphere (except the geomagnetic equator region). The mechanism of this effect remains unexplained.
¶rt;m u m nu mau nam aum n () ¶rt; u 1963–69. u m u ¶rt; nm ¶rt; a mau. mm ¶rt;a m¶rt; muna m. aum m u, a¶rt;a aum amumu, u u ¶rt; F2 amu uuaum ama. mu u m ¶rt;mu uu aum amumu, m a nu mau . n mun m nu, a¶rt; aumu mn u ¶rt; ¶rt;- u uum u (a uu amuaum ama). au m ma um.相似文献
120.
Summary The algorithm of iterative geophysical tomography is presented. The medium is approximated smoothly by means of B-splines. The tww-point problem of ray computation is solved with the aid of paraxial approximation. The parameters of the medium are obtained from the iterative algorithm of minimizing the quadratic form. Two numerical 2-D examples are given.
u¶rt; au umamuuu mauu. ¶rt;a annuuaa n nu nu -na. ma na aa a nu nu naaua annuauu. aam ¶rt; n a umamu aua uuauauu a¶rt;amu . am nu¶rt; ¶rt;a 2-D u nua.相似文献