Correlation Between Local Slip Rate and Local High-frequency Seismic Radiation in an Earthquake Fault     

Alexander A. Gusev  Eugenia M. Guseva  Giuliano F. Panza 《Pure and Applied Geophysics》2006,163(7):1305-1325

For any earthquake, the slipping fault and the source of high-frequency seismic waves, by and large, coincide. On a more local scale, however, the areas of high seismic slip rate and of increased high-frequency radiation output (seismic luminosity) need not match. To study in some detail how slip rate and seismic luminosity are interrelated, a systematic study is performed that uses 251 records of teleseismic P waves from 23 intermediate-depth earthquakes of magnitude 6.8 and above. From a broadband trace we extract two time histories: (1) displacement and (2) 0.5–2.5 Hz band-passed and squared velocity, or ``HF power', and calculate correlation coefficient, ρ between the two. To reduce the bias related to formation of P coda, a special procedure is applied to data. We estimated the average value ρ = 0.52 (range of event averages 0.35 to 0.65) for the correlation coefficient between the radiated time histories for displacement and ``HF power', which is considerably below the ``ideal' value of unity. We argue that the same or even lower value characterizes the degree of slip rate - seismic luminosity correlation at the fault. Two factors may contribute to the revealed decorrelation: (1) random fluctuations of observed HF power (inevitable for a signal with a limited bandwidth), and (2) the genuine mismatch of slip rate and mean luminosity. We show that these factors, acting separately, would result in the ρ values equal to, correspondingly, 0.72 and 0.80. We also show that genuine decorrelation is statistically significant. We conclude that the observed values of ρ indicate genuine differences between the distributions of the slip rate and the seismic luminosity over the fault area. These results provide important constraints both for the accurate wide-band simulation of strong ground motion and for theoretical dynamic source models.  相似文献   

Size and duration of the high-frequency radiator in the source of the 2004 December 26 Sumatra earthquake     

A. A. Gusev  E. M. Guseva  G. F. Panza 《Geophysical Journal International》2007,170(3):1119-1128

We recover the gross space–time characteristics of high-frequency (HF) radiator of the great Sumatra-Andaman islands earthquake of 2004 December 26 ( M _w= 9.1–9.3) using the time histories of the power of radiated HF P waves. To determine these time histories we process teleseismic P waves at 36 BB stations, using, in sequence: (1) bandpass filtering (four bands: 0.4–1.2, 1.2–2, 2–3 and 3–4 Hz); (2) squaring wave amplitudes, making 'power signals' for each band and (3) stripping the propagation-related distortion ( P coda, etc.) from the power signal and thus recovering source time function for HF power. In step (3) we employ an inverse filter constructed from an empirical Green's function, which is estimated as the power signal from an aftershock. For each ray we thus obtain signals with relatively well-defined end and no coda. From these signals we extract: total duration (joint estimate for all four bands) and temporal centroid of signal power for each band. Through linear inversion, the set of duration values for a set of rays delivers estimates of the rupture stopping point and stopping time. Similarly, the set of temporal centroids can be inverted to obtain the position of the space–time centroid of HF energy radiator. The quality of inversion for centroid is acceptable for lower-frequency bands but deteriorates for higher-frequency bands where only a fraction of stations provide useful data. For the source length and duration the following joint estimates were obtained: 1241 ± 224 km, 550 ± 10 s. The estimated stopping point position corresponds to the northern extremity of the aftershock zone. Spatial HF radiation centroids are located at distances 350–700 km from the epicentre, in a systematic way: the higher is the frequency, the farther is the centroid from the epicentre. Average rupture propagation velocity is estimated as 2.25 km s^–1.  相似文献   

Modeling of the ground motion for the Petropavlovsk earthquake of November 24, 1971 (M = 7.6)     

A. A. Gusev  E. M. Guseva  V. M. Pavlov 《Izvestiya Physics of the Solid Earth》2009,45(5):395-405

Based on the example of the strong earthquake of November 24, 1971, with the earthquake source near the Petropavlovsk-Kamchatskii, the new modeling technique of the strong ground motions within the broadband is tested. In this technique, the seismologically-substantiated models of the radiation source and elastic medium are used. The source is represented by an array of point radiation sources-dislocations with the random seismic moments (amplitudes) and with the random time functions. The new method of calculation of the Green functions is developed to describe the propagation of waves and residual displacements of a layered medium. The method is used for the simulation of the horizontal ground motion, recorded by a S5S-ISO instrument for the strong earthquake that took place on November 24, 1971 with the source near the Petropavlovsk-Kamchatskii (with a depth of 105 km). The position of the hypocenter, the sizes and the position of the fault, and “fault mechanism” were considered to be known a priori. By a trial and error method of the duration of the source process and only two spectral parameters, it was possible to simulate successfully the fundamental characteristics of the ground vibrations: the amplitude of acceleration, the velocity and displacement of the ground, their Fourier spectrum, the duration of the vibrations, and the response spectrum. The surprisingly high level of high-frequency radiation, probably connected with the intraplate position of the source, is a specific feature of the source.  相似文献   

Chromospheric and Coronal Radio Sources from Observations of the Partial Solar Eclipse of March 20, 2015, at the Mountain Astronomical Station of the Central Astronomical Observatory     

A.?D.?ShramkoEmail author  S.?A.?Guseva 《Geomagnetism and Aeronomy》2018,58(4):464-468

This paper presents the results of processing the data on the partial solar eclipse that occurred on March 20, 2015, and was observed with the RT-3 (λ = 4.9 cm) and RT-2 (λ = 3.2 cm) radio telescopes of the Kislovodsk Mountain Astronomical Station, Central Astronomical Observatory, Russian Academy of Sciences (MAS CAO RAS). They were compared with observations in the optical and X-ray ranges. The local radio sources at the limb and on the disc of the Sun were identified: an eruptive and a quiet prominence; filaments; a coronal hole; facular plages; and a sunspot group. The curves of the center-to-limb variations in the radio brightness of the undisturbed regions of the Sun were plotted for λ = 4.9 and λ = 3.2 cm. The solar radio maps were presented. The altitude of the radiating layer in the chromosphere above the sunspot and the facular sources for λ = 4.9 cm λ = 3.2 cm was compared.  相似文献   

Formation of the chemical composition of brackish and brine groundwater in the Tuva depression and surrounding areas     

N.V. Guseva  Yu.G. Kopylova  Ch.K. Oidup  K.D. Arakchaa  K.M. Rychkova  A.A. Khvashchevskaya  O.D. Ayunova 《Russian Geology and Geophysics》2018,59(2):135-143

Groundwater with high salinity is widespread in different climatic and geologic environments of the world. The formation of its chemical composition, however, is still debatable. The chemical composition of groundwater has been studied in 19 springs of the Tuva depression. In this area, hydrocarbonate, sulfate, and chloride waters with different cation compositions discharge. Their TDS value varies mainly from 1 to 6 g/L, reaching 315 g/L at only one locality. The chemical composition of the studied waters is reflective of the geostructural, hydrogeologic, landscape, and geochemical conditions. The main processes determining the chemical composition of the waters are their interaction with aluminosilicate minerals, dissolution of gypsum and halite, evaporation, and oxidation of sulfide minerals.  相似文献   

Study of the region of star formation 2 mon. The region of the cluster NGC 2244     

N. G. Guseva 《Astrophysics》1985,22(3):299-305

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Geochemical types of natural waters in the interfluve of the Enzor’yakhi and the Yun’yakhi (eastern slope of the Polar Urals)     

N. V. Guseva  Yu. G. Kopylova  A. A. Khvashchevskaya 《Water Resources》2013,40(4):417-425

Natural-water chemistry in the interfluve of the Enzor’yakhi and the Yun’yakhi rivers (the eastern slope of the Polar Urals) is characterized in terms of the ratios of major ions belonging to hydrocarbonate calcium-magnesium and magnesium-calcium chemical types. From the viewpoint of evolution of the water-rock system in the region, five geochemical types of water were identified by the degree of their equilibrium with secondary minerals, reflecting different formation conditions of their chemistry. A specific feature of the region is the formation of waters of organogenic geochemical type, which are considerably enriched by organic matter, determining the specifics of migration of some chemical elements in such waters.  相似文献   

Petrology of a Late Archaean, Highly Potassic, Sanukitoid Pluton from the Baltic Shield: Insights into Late Archaean Mantle Metasomatism   总被引：1，自引：0，他引：1  

Lobach-Zhuchenko  S. B.; Rollinson  H.; Chekulaev  V. P.; Savatenkov  V. M.; Kovalenko  A. V.; Martin  H.; Guseva  N. S.; Arestova  N. A. 《Journal of Petrology》2008,49(3):393-420

The late Archaean Panozero pluton in Central Karelia (BalticShield) is a multi-phase high-Mg, high-K intrusion with sanukitoidaffinities, emplaced at 2·74 Ga. The magmatic historyof the intrusion may be subdivided into three cycles and includesmonzonitic and lamprophyric magmas. Compositional variationsare most extreme in the monzonite series and these are interpretedas the result of fractional crystallization. Estimates of thecomposition of the parental magmas to the monzonites and lamprophyresshow that they are enriched in light rare earth elements, Sr,Ba, Cr, Ni and P but have low contents of high field strengthelements. Radiogenic isotope data indicate a low U/Pb, highTh/U, high Rb/Sr, low Sm/Nd source. The magmatic rocks of thePanozero intrusion are also enriched in H₂O and CO₂; carbonisotope data are consistent with mantle values, indicating afluid-enriched mantle source. The similarity in trace elementcharacter of all the Panozero parental magmas indicates thatall the magmas were derived from a similar mantle source. Thepattern of trace element enrichment is consistent with a mantlesource enriched by fluids released from a subducting slab. Nd-isotopedata suggest that this enrichment took place at c. 2·8Ga, during the main episode of greenstone belt and tonalite–trondhjemite–granodioriteformation in Central Karelia. Sixty million years later, at2·74 Ga, the subcontinental mantle melted to form thePanozero magmas. Experimental studies suggest that the monzoniticmagmas originated by the melting of pargasite–phlogopitelherzolite in the subcontinental mantle lithosphere at 1–1·5GPa. The precise cause of the melting event at 2·74 Gais not known, although a model involving upwelling of asthenosphericmantle following slab break-off is consistent with the geochemicalevidence for the enrichment of the Karelian subcontinental mantlelithosphere by subduction fluids. KEY WORDS: Archaean; sanukitoid; monzonite; Karelia; mantle metasomatism  相似文献   

Geology and petrology of the archean high-K and high-Mg Panozero massif,Central Karelia     

S. B. Lobach-Zhuchenko  H. Rollinson  V. P. Chekulaev  N. S. Guseva  N. A. Arestova  A. V. Kovalenko 《Petrology》2007,15(5):459-487

The high-K and high-Mg Panozero central-type intrusion is located on the shore of Lake Segozero, Central Karelia, and has an age of 2737 ± 10 Ma. Detailed mapping and petrological study showed that it was formed in three magmatic cycles that were separated by lamprophyre dikes. The first cycle is composed mainly of mafic rocks (layered complex: pyroxenites-honblendites-monzogabbro) and monzonites 1; the second cycle includes monzonites 2, and the third cycle comprises monzonites 3 and quartz monzonites. The massif is cut by numerous lamprophyre dikes and breccia zones. As compared to calc-alkaline series, the studied rocks are enriched in K, Ba, Sr, P, LREE, have high mg# (mg# = 0.5–0.65), and elevated contents of Cr and Ni. The parent composition of the layered complex was determined to be monzogabbro. Model calculations showed that the compositional variations of the Panozero Complex are consistent with the fractional crystallization of monzogabbro. The melts were fractionated in an intermediate chamber and during the flowing and crystallization of the magma. The parent melt of the intrusion was formed by the partial melting of mantle enriched in some LILE, LREE, and volatiles (CO₂ and H₂O). The volatile enrichment of the melt manifests itself in the mineral composition of the rocks, the presence of primary gas inclusions in apatite, and diverse structural features. The comparison of the rocks of the Panozero Massif with metasomatized mantle xenoliths in the variation diagrams for incompatible elements showed that the mantle source of the Panozero Complex was metasomatized by fluid consisting of H₂O and CO₂ of different origin.  相似文献   

Archean age of miaskite lamproites from the Panozero complex, Karelia     

S. A. Sergeev  S. B. Lobach-Zhuchenko  A. N. Larionov  N. G. Berezhnaya  N. S. Guseva 《Doklady Earth Sciences》2007,413(3):420-423

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