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1.
Global regression relations for conversion of surface wave and body wave magnitudes to moment magnitude 总被引:1,自引:0,他引:1
A homogenous earthquake catalog is a basic input for seismic hazard estimation, and other seismicity studies. The preparation
of a homogenous earthquake catalog for a seismic region needs regressed relations for conversion of different magnitudes types,
e.g. m
b
, M
s
, to the unified moment magnitude M
w. In case of small data sets for any seismic region, it is not possible to have reliable region specific conversion relations
and alternatively appropriate global regression relations for the required magnitude ranges and focal depths can be utilized.
In this study, we collected global events magnitude data from ISC, NEIC and GCMT databases for the period 1976 to May, 2007.
Data for mb magnitudes for 3,48,423 events for ISC and 2,38,525 events for NEIC, M
s
magnitudes for 81,974 events from ISC and 16,019 events for NEIC along with 27,229 M
w
events data from GCMT has been considered. An epicentral plot for M
w
events considered in this study is also shown. M
s
determinations by ISC and NEIC, have been verified to be equivalent. Orthogonal Standard Regression (OSR) relations have
been obtained between M
s
and M
w
for focal depths (h < 70 km) in the magnitude ranges 3.0 ≤ M
s
≤ 6.1 and 6.2 ≤ M
s
≤ 8.4, and for focal depths 70 km ≤ h ≤ 643 km in the magnitude range 3.3 ≤ M
s
≤ 7.2. Standard and Inverted Standard Regression plots are also shown along with OSR to ascertain the validation of orthogonal
regression for M
s
magnitudes. The OSR relations have smaller uncertainty compared to SR and ISR relations for M
s
conversions. ISR relations between m
b
and M
w
have been obtained for magnitude ranges 2.9 ≤ m
b
≤ 6.5, for ISC events and 3.8 ≤ m
b
≤ 6.5 for NEIC events. The regression relations derived in this study based on global data are useful empirical relations
to develop homogenous earthquake catalogs in the absence of regional regression relations, as the events catalog for most
seismic regions are heterogeneous in magnitude types. 相似文献
2.
H. M. Hussein K. M. Abou Elenean I. A. Marzouk A. Peresan I. M. Korrat E. Abu El-Nader G. F. Panza M. N. El-Gabry 《Natural Hazards》2008,47(3):525-546
The aim of the present work is to compile and update a catalogue of the instrumentally recorded earthquakes in Egypt, with
uniform and homogeneous source parameters as required for the analysis of seismicity and seismic hazard assessment. This in
turn requires a detailed analysis and comparison of the properties of different available sources, including the distribution
of events with time, the magnitude completeness, and the scaling relations between different kinds of magnitude reported by
different agencies. The observational data cover the time interval 1900–2004 and an area between 22°–33.5° N and 25°–36° E.
The linear regressions between various magnitude types have been evaluated for different magnitude ranges. Using the best
linear relationship determined for each available pair of magnitudes, as well as those identified between the magnitudes and
the seismic moment, we convert the different magnitude types into moment magnitudes M
W, through a multi-step conversion process. Analysis of the catalogue completeness, based on the M
W thus estimated, allows us to identify two different time intervals with homogeneous properties. The first one (1900–1984)
appears to be complete for M
W ≥ 4.5, while the second one (1985–2004) can be considered complete for magnitudes M
W ≥ 3. 相似文献
3.
A regional time and magnitude predictable model has been applied to estimate the recurrence intervals for large earthquakes
in the vicinity of 8 October 2005 Kashmir Himalaya earthquake (25°–40°N and 65°–85°E), which includes India, Pakistan, Afghanistan,
Hindukush, Pamirs, Mangolia and Tien-Shan. This region has been divided into 17 seismogenic sources on the basis of certain
seismotectonics and geomorphological criteria. A complete earthquake catalogue (historical and instrumental) of magnitude
Ms ≥ 5.5 during the period 1853–2005 has been used in the analysis. According to this model, the magnitude of preceding earthquake
governs the time of occurrence and magnitude of future mainshock in the sequence. The interevent time between successive mainshocks
with magnitude equal to or greater than a minimum magnitude threshold were considered and used for long-term earthquake prediction
in each of seismogenic sources. The interevent times and magnitudes of mainshocks have been used to determine the following
predictive relations: logT
t = 0.05 M
min + 0.09 M
p − 0.01 log M
0 + 01.14; and M
f = 0.21 M
min − 0.01 M
p + 0.03 log M
0 + 7.21 where, T
t is the interevent time of successive mainshocks, M
min is minimum magnitude threshold considered, M
p is magnitude of preceding mainshock, M
f is magnitude of following mainshock and M
0 is the seismic moment released per year in each seismogenic source. It was found that the magnitude of following mainshock
(M
f) does not depend on the interevent time (T
t), which indicates the ability to predict the time of occurrence of future mainshock. A negative correlation between magnitude
of following mainshock (M
f) and preceding mainshock (M
p) indicates that the larger earthquake is followed by smaller one and vice versa. The above equations have been used for the
seismic hazard assessment in the considered region. Based on the model applicability in the studied region and taking into
account the occurrence time and magnitude of last mainshock in each seismogenic source, the time-dependent conditional probabilities
(PC) for the occurrence of next shallow large mainshocks (Ms ≥ 6.5), during next 20 years as well as the expected magnitudes
have been estimated. 相似文献
4.
North-east India is seismically very active and has experienced many widelydistributed shallow, large earthquakes. Earthquake
generation model for the region was studied using seismicity data [(1906–1984) prepared by National Geophysical Data Centre
(NGDC), Boulder Colorado, USA]. For establishing statistical relations surface wave magnitudes (M
s≥5·5) have been considered. In the region four seismogenic sources have been identified which show the occurrences of atleast
three earthquakes of magnitude 5·5≤M
s≤7·5 giving two repeat times. It is observed that the time interval between the two consecutive main shock depends on the
preceding main shock magnitude (M
p) and not on the following main shock magnitude (M
f) revealing the validity of time predictable model for the region. Linear relation between logarithm of repeat time (T) and preceding main shock magnitude (M
p) is established in the form of logT=cM
p+a. The values ofc anda are estimated to be 0–36 and 1–23, respectively. The relation may be used for seismic hazard evaluation in the region. 相似文献
5.
R. B. S. Yadav J. N. Tripathi D. Shanker B. K. Rastogi M. C. Das Vikas Kumar 《Natural Hazards》2011,56(1):145-167
The return periods and occurrence probabilities related to medium and large earthquakes (M
w
4.0–7.0) in four seismic zones in northeast India and adjoining region (20°–32°N and 87°–100°E) have been estimated with
the help of well-known extreme value theory using three methods given by Gumbel (1958), Knopoff and Kagan (1977) and Bury (1999). In the present analysis, the return periods, the most probable maximum magnitude in a specified time period and probabilities
of occurrences of earthquakes of magnitude M ≥ 4.0 have been computed using a homogeneous and complete earthquake catalogue prepared for the period between 1897 and 2007.
The analysis indicates that the most probable largest annual earthquakes are close to 4.6, 5.1, 5.2, 5.5 and 5.8 in the four
seismic zones, namely, the Shillong Plateau Zone, the Eastern Syntaxis Zone, the Himalayan Thrusts Zone, the Arakan-Yoma subduction
zone and the whole region, respectively. The most probable largest earthquakes that may occur within different time periods
have been also estimated and reported. The study reveals that the estimated mean return periods for the earthquake of magnitude
M
w
6.5 are about 6–7 years, 9–10 years, 59–78 years, 72–115 years and 88–127 years in the whole region, the Arakan-Yoma subduction
zone, the Himalayan Thrusts Zone, the Shillong Plateau Zone and the Eastern Syntaxis Zone, respectively. The study indicates
that Arakan-Yoma subduction zone has the lowest mean return periods and high occurrence probability for the same earthquake
magnitude in comparison to the other zones. The differences in the hazard parameters from zone to zone reveal the high crustal
heterogeneity and seismotectonics complexity in northeast India and adjoining regions. 相似文献
6.
Several relatively thin tectono-metamorphic slices have been recognized in the Cycladic eclogite–blueschist belt, through
detailed studies on Ios, Sifnos, Syros, and Tinos. A sequence of distinct metamorphic mineral growth events has been documented.
These recur in each tectonic slice, although individual slices are dominated by different events. To constrain the timing
of these processes, the method of asymptotes and limits has been used to reanalyze published 40Ar/39Ar apparent age spectra. This reanalysis supports the concept that there were separate and quite distinct high-pressure metamorphic
mineral growth events, and allows potential constraints as to the timing of some of these events to be developed. M1B eclogite-facies metamorphism is estimated to have occurred at some time in the period 53–49 Ma, the M1C blueschist-facies metamorphic event at some time in the period 44–38 Ma, and the M1D transitional blueschist-facies metamorphic event is estimated to have occurred at some time in the period 35–30 Ma. A kinematic
model is proposed to explain the geometry of a thinly sliced tectono-metamorphic stratigraphy, as observed, and the reason
as to why individual tectonic slices in this ‘tectono-metamorphic stratigraphy’ should display distinctive patterns of fabrics
and micro-structures, as well as characteristic temperature-time curves as inferred by 40Ar/39Ar geochronology. 相似文献
7.
Turkey has been divided into eight different seismic regions taking into consideration the tectonic environments and epicenters
of the earthquakes to examine relationships of the modal values (a/b), the expected maximum magnitudes (Mmax) and the maximum intensities (Imax). For this purpose, the earthquakes for the time period 1900–1992 from the Global Hypocenter Data Base CD-ROM prepared by
USGS, and for the time period 1993–2001 from the PDE data and IRIS data are used. Concerning the relationships developed between
different magnitude scales and between surface wave magnitudes (MS) and intensity for different source regions in Turkey, we have constructed a uniform catalog of MS. We have estimated the values of Mmax and Imax using the Gumbel III asymptotic distribution. Highest a-values are observed in the Aegean region and the lowest b-values are estimated for the North Anatolian Fault. Maximum values of a/b, Mmax and Imax are related to the eastern and western part of the North Anatolian Fault and the Aegean Arc. The lowest values of all parameters
are observed near the Mid Anatolian Fault system. Linear relationships have been calculated between a/b, Mmax and Imax using orthogonal regression. If one of the three parameters is computed, two other parameters can be calculated empirically
using these linear relationships. Hazard maps of Mmax and Imax values are produced using these relationships for a grid of equally spaced points at 1°. It is observed that the maps produced
empirically may be used as a measure of seismic hazard in Turkey. 相似文献
8.
Emad A. M. S. Al-Heety 《Arabian Journal of Geosciences》2014,7(11):4727-4732
A complete and homogeneous magnitude earthquake catalogue spanning the period 1900 to 2010 was created. The catalogue covers the area 29° to 37.5° N and 39° to 48° E. Entries in the new earthquake catalogue were cross checked and additions made from various sources of earthquake records to ensure that repetitions are not included in this analysis. Events were considered duplicates if they had a time difference of 10 s or less and space origin difference of 0.5° or less. In a given set of duplicate events, an event, which had a magnitude and International Seismological Center source, was retained as the record of the event. The unified magnitude scale, the moment magnitude (M w), was applied throughout the catalogue. The M w for 18 events was reported. The M w for other events was estimated using empirical relations between m b, M s, M L, and M w. Magnitude of completeness, M c, was estimated using the maximum curvature. It was 4.3 M w. Finally, a list of 213 events from 1900 to 2010 with M w?≥?4.3 is presented. The list is considered complete for the period from 1962 to 2010. 相似文献
9.
An attempt has been made to quantify the variability in the seismic activity rate across the whole of India and adjoining
areas (0–45°N and 60–105°E) using earthquake database compiled from various sources. Both historical and instrumental data
were compiled and the complete catalog of Indian earthquakes till 2010 has been prepared. Region-specific earthquake magnitude
scaling relations correlating different magnitude scales were achieved to develop a homogenous earthquake catalog for the
region in unified moment magnitude scale. The dependent events (75.3%) in the raw catalog have been removed and the effect
of aftershocks on the variation of b value has been quantified. The study area was divided into 2,025 grid points (1°×1°) and the spatial variation of the seismicity
across the region have been analyzed considering all the events within 300 km radius from each grid point. A significant decrease
in seismic b value was seen when declustered catalog was used which illustrates that a larger proportion of dependent events in the earthquake
catalog are related to lower magnitude events. A list of 203,448 earthquakes (including aftershocks and foreshocks) occurred
in the region covering the period from 250 B.C. to 2010 A.D. with all available details is uploaded in the website . 相似文献
10.
We present JHKLM photometry of the carbon stars ST And and T Lyn acquired in 2000–2010. Along with brightness variations due to pulsations,
changes on timescales of 2000–3000 days are also observed. Our combined light curves can be satisfactorily represented with
light elements derived from visual observations, but the maxima are delayed relative to the calculated times. A color-index
analysis demonstrates that the dust shell of ST And is fairly weak, and is manifest only episodically, while the presence
of hot dust was always detected for T Lyn. These results confirm models of spherically symmetric stellar dust shells based
on mean-flux data, supplemented with observations in the intermediate IR from the IRAS and AKARI satellites. The visual optical
depth of the relatively cool dust shell of ST And assuming a dust temperature at the inner edge of T
1 = 510 K is very low: τ
V = 0.047. The dust shell of T Lyn is considerably hotter (T
1 = 940 K), with τ
V = 0.95. We estimate the mass-loss rate to be 1.8 × 10−7
M
⊙/year for ST And and 3.7 × 10−7
M
⊙/year for T Lyn. 相似文献
11.
Wen Su Ming Zhang Simon A. T. Redfern Jun Gao Reiner Klemd 《International Journal of Earth Sciences》2009,98(6):1299-1309
Chemically-zoned amphibole porphyroblast grains in an eclogite (sample ws24-7) from the western Tianshan (NW-China) have been
analyzed by electron microprobe (EMP), micro Fourier-transform infrared (micro-FTIR) and micro-Raman spectroscopy in the OH-stretching
region. The EMP data reveal zoned amphibole compositions clustering around two predominant compositions: a glaucophane end-member
(
B
Na2
C
M2+
3 M3+
2
T
Si8(OH)2) in the cores, whereas the mantle to rim of the samples has an intermediate amphibole composition (
A
0.5
B
Ca1.5Na0.5
C
M
2+
4.5 M
0.53+
T
Si7.5Al0.5(OH)2) (A = Na and/or K; M
2+ = Mg and Fe2+; M
3+ = Fe3+ and/or Al) between winchite (and ferro-winchite) and katophorite (and Mg-katophorite). Furthermore, we observed complicated
FTIR and Raman spectra with OH-stretching absorption bands varying systematically from core to rim. The FTIR/Raman spectra
of the core amphibole show three lower-frequency components (at 3,633, 3,649–3,651 and 3,660–3,663 cm−1) which can be attributed to a local O(3)-H dipole surrounded by
M(1) M(3)Mg3,
M(1) M(3)Mg2Fe2+ and
M(1) M(3) Fe2+
3, respectively, an empty A site and
T
Si8 environments. On the other hand, bands at higher frequencies (3,672–3,673, 3,691–3,697 and 3,708 cm−1) are observable in the rims of the amphiboles, and they indicate the presence of an occupied A site. The FTIR and Raman data from the OH-stretching region allow us to calculate the site occupancy of the A, M(1)–M(3), T sites with confidence when combined with EPM data. By contrast M(2)- and M(4) site occupancies are more difficult to evaluate. We use these samples to highlight on the opportunities and limitations
of FTIR OH-stretching spectroscopy applied to natural high pressure amphibole phases. The much more detailed cation site occupancy
of the zoned amphibole from the western Tianshan have been obtained by comparing data from micro-chemical and FTIR and/or
Raman in the OH-stretching data. We find the following characteristic substitutions Si(T-site) (Mg, Fe)[M(1)–M(3)-site] → Al(T-site) Al[M(1)–M(3)-site] (tschermakite), Ca(M4-site)□ (A-site) → Na(M4-site) Na + K(A-site) (richterite), and Ca(M4-site) (Mg, Fe) [M(1)–M(3)-site] → Na(M4-site) Al[M(1)–M(3)-site] (glaucophane) from the configurations observed during metamorphism. 相似文献
12.
The Vienna Basin Transfer Fault (VBTF) is a slow active fault with moderate seismicity (I
max~8–9, M
max~5.7) passing through the most vulnerable regions of Austria and Slovakia. We use different data to constrain the seismic
potential of the VBTF including slip values computed from the seismic energy release during the 20th century, geological data
on fault segmentation and a depth-extrapolated 3-D model of a generalized fault surface, which is used to define potential
rupture zones. The seismic slip of the VBTF as a whole is in the range of 0.22–0.31 mm/year for a seismogenic fault thickness
of 8 km. Seismic slip rates for individual segments vary from 0.00 to 0.77 mm/year. Comparing these data to geologically and
GPS-derived slip velocities (>1 mm/year) proofs that the fault yields a significant seismic slip deficit. Segments of the
fault with high seismic slip contrast from segments with no slip representing locked segments. Fault surfaces of segments
within the seismogenic zone (4–14 km depth) vary from 55 to 400 km2. Empirical scaling relations show that these segments are sufficiently large to explain both, earthquakes observed in the
last centuries, and the 4th century Carnuntum earthquake, for which archeo-seismological data suggest a magnitude of M ≥ 6. Based on the combination of all data (incomplete earthquake catalog, seismic slip deficits, locked segments, potential
rupture areas, indications of strong pre-catalog earthquakes) we argue, that the maximum credible earthquake for the VBTF
is in the range M
max = 6.0–6.8, significantly larger than the magnitude of the strongest recorded events (M = 5.7). 相似文献
13.
Y. J. Bhaskar Rao T. R. K. Chetty A. S. Janardhan K. Gopalan 《Contributions to Mineralogy and Petrology》1996,125(2-3):237-250
Sittampundi and Bhavani Archean layered meta-anorthosite complexes occur as tectonic lenses within the Cauvery shear zone
(CSZ), a crustal scale shear dividing the Precambrian granulite crust of south India into late Archean (> 2.5 Ga) and Proterozoic (c. 0.55 Ga) blocks. They and their host supracrustal-gneiss rocks record at least two stages of
tectonometamorphic history. The first is seen as regional scale refolded isoclinal folds and granulite metamorphism (D1-M1) while the second stage is associated with dominantly E–W dextral transcurrent shearing and metamorphic recrystallisation
(D2-MCSZ). Whole rock Sm-Nd isochrons for several comagmatic rocks of the layered complexes yield concordant ages: Sittampundi – 2935±60
Ma, ɛNd + 1.85±0.16 and Bhavani – 2899±28 Ma, ɛNd + 2.18±0.14 (2σ errors). Our Sm-Nd results suggest that: (1) the magmatic protoliths of the Sittampundi and Bhavani layered
complexes were extracted from similar uniform and LREE depleted mantle sources; (2) M1 metamorphism occurred soon after emplacement at c.3.0 Ga ago. P-T estimates on garnet granulites from the Sittampundi complex characterise the MCSZ as a high-P event with metamorphic peak conditions of c. 11.8 kbar and 830°C (minimum). The MCSZ is associated with significant isothermal decompression of the order of 4.5–3.5 kbar followed by static high-temperature
rehydration and retrogression around 600°C. The timing of MCSZ is inferred to be Neoproterozoic at c. 730 Ma based on a whole rock-garnet-plagioclase-hornblende Sm-Nd isochron age for
a garnet granulite from the Sittampundi complex and its agreement with the 800–600 Ma published age data on post-kinematic
plutonic rocks within the CSZ. These results demonstrate that the Cauvery shear zone is a zone of Neoproterozoic reworking
of Archean crust broadly similar to the interface between the Napier and Rayner complexes of the East Antarctic shield in
a model Proterozoic Gondwana supercontinent.
Received: 5 December 1995 / Accepted: 3 May 1996 相似文献
14.
I. N. Tikhonov 《Russian Journal of Pacific Geology》2012,6(1):78-85
The characteristics of the distributions of the time differences occurrence of the consecutive earthquakes in the Kuril-Kamchatka
zone, including the Hokkaido Island area, have been investigated in various magnitude ranges. For the purpose of the analysis,
we used the data from the regional and world earthquake catalogs for the last 20 years. As a result of this analysis, a new
intermediate-term precursor effect has been found: a quiescence period observed prior to the strongest earthquakes. This precursor
manifests itself in the form of the long-term (2–6 months) absence of events with M ≥ 5.5 within the territory. For the predictive purposes, it was proposed to replace the quiescence period by such a more
stable parameter as the sum of the three longest intervals between the earthquakes with M ≥ 5.0 in a sliding time window. The prognostic informativeness of this parameter has been assessed. 相似文献
15.
Homogeneous Indian Monsoon rainfall: Variability and prediction 总被引:1,自引:0,他引:1
The Indian summer monsoon rainfall is known to have considerable spatial variability, which imposes some limitations on the
all-India mean widely used at present. To prepare a spatially coherent monsoon rainfall series for the largest possible area,
fourteen subdivisions covering the northwestern and central parts of India (about 55% of the total area of the country), having
similar rainfall characteristics and associations with regional/global circulation parameters are merged and their area-weighted
means computed, to form monthly and seasonal Homogeneous Indian Monsoon (HIM) rainfall series for the period 1871–1990. This
paper includes a listing of monthly and seasonal rainfall of HIM region. HIM rainfall series has been statistically analysed
to understand its characteristics, variability and teleconnections for long-range prediction.
HIM rainfall series isfound to be homogeneous, Gaussian distributed and free from persistence. The mean (R) rainfall is 757
mm (87% of annual) and standard deviation (S) 119 mm, with a Coefficient of Variation (CV) of 16%. There were 21 dry (K, -<R S) and 19 wet (R
i R + S) years during 1871–1990. There were clusters of frequent negative departures during 1899–1920 and 1965–1987 and positive
departures during 1942–1961. The recent three decades show very high rainfall variability with 10 dry and 6 wet years. The
decadal averages were alternatively positive and negative for three consecutive decades, viz., 1871–1900 (positive); 1901–1930
(negative); 1931–1960 (positive) and 1961–1990 (negative) respectively. Significant QBO and autocorrelation at 14th lag have
been found in HIM rainfall series.
To delineate the changes in the climatic regime of the Indian summer monsoon, sliding correlation coefficients (CCs) between
HIM rainfall series and (i) Bombay msl pressure, (ii) Darwin msl pressure and (iii) Northern Hemisphere surface air temperature
over the period 1871–1990 have been examined. The 31-year sliding CCs showed the systematic turning points of positive and
negative CCs around the years, 1900 and 1940. In the light of other corroborative evidences, these turning points seem to
delineate ‘meridional’ monsoon regime during 1871–1900 and 1940–1990 and ‘zonal’ monsoon regime during 1901–1940. The monsoon
signal is particularly dominant in many regional and global circulation parameters, during 1951–1990.
Using the teleconnections ofHIM series with 12 regional/global circulation parameters during the recent 36-year period 1951–86 regression models have been
developed for long-range prediction. In the regression equations 3 to 4 parameters were entered, explaining upto 80% of the
variance, depending upon the data period. The parameters that prominently enter the multiple regression equations are (i)
Bombay msl pressure, (ii) April 500 mb Ridge at 75°E, (iii) NH temperature, (iv) Nouvelle minus Agalega msl pressure and (v)
South American msl pressure. Eleven circulation parameters for the period 1951–80 were subjected to Principal Component Analysis
(PCA) and the PC’s were used in the regression model to estimate HIM rainfall. The multiple regression with three PCs explain
72% of variance in HIM rainfall. 相似文献
16.
P. A. van Aken V. J. Styrsa B. Liebscher A. B. Woodland G. J. Redhammer 《Physics and Chemistry of Minerals》1999,26(7):584-590
The Fe M
2,3-edge spectra of solid solutions of garnets (almandine-skiagite Fe3(Al1–xFex)2[SiO4]3 and andradite-skiagite (Fe1–xCax)3Fe2[SiO4]3), pyroxenes (acmite-hedenbergite (Ca1–xNax)(Fe2+
1−xFe3+
x)Si2O6), and spinels (magnetite-hercynite Fe(Al1–xFex)2O4) have been measured using the technique of parallel electron energy-loss spectroscopy (EELS) conducted in a transmission
electron microscope (TEM). The Fe M
2,3 electron energy-loss near-edge structures (ELNES) of the minerals exhibit a characteristic peak located at 4.2 eV and 2.2 eV
for trivalent and divalent iron, respectively, prior to the main maximum at about 57 eV. The intensity and energy of the pre-edge
feature varies depending on Fe3+/ΣFe. We demonstrate a new quantitative method to extract the ferrous/ferric ratio in minerals. A systematic relationship
between Fe3+/ΣFe and the integral intensity ratio of the main maximum and the pre-edge peak of the Fe M
2,3 edge is observed. Since the partial cross sections of the Fe M
2,3 edges are some orders of magnitude higher than those of the Fe L
2,3 edges, the Fe M
2,3 edges are interesting for valence-specific imaging of Fe. The possibility of iron valence-specific imaging is illustrated
by Fe M
2,3-ELNES investigations with high lateral resolution from a sample of ilmenite containing hematite exsolution lamellae that
shows different edge shapes consistent with variations in the Fe3+/ΣFe ratio over distances on the order of 100 nm.
Received: 14 April 1998 / Revised, accepted: 8 March 1999 相似文献
17.
Reena De S. G. Gaonkar B. V. Srirama Sagina Ram J. R. Kayal 《Journal of Earth System Science》2003,112(3):413-419
A 12-station temporary microearthquake network was established by the Geological Survey of India for aftershock monitoring
of the January 26th, 2001 Bhuj earthquake (M
w 7.6) in the Kutch district of Gujarat state, western India. The epicentres of the aftershocks show two major trends: one
in the NE direction and the other in the NW direction. Fault-plane solutions of the best-located and selected cluster of events
that occurred along the NE trend, at a depth of 15–38 km, show reverse faulting with a large left-lateral strike-slip motion,
which are comparable with the main-shock solution. The NW trending upper crustal aftershocks at depth <10 km, on the other
hand, show reverse faulting with right-lateral strike-slip motion, and the mid crustal and lower crustal aftershocks, at a
depth of 15–38 km, show pure reverse faulting as well as reverse faulting with right-lateral and left-lateral strike-slip
motions; these solutions are not comparable with the main-shock solution. It is inferred that the intersection of two faults
has been the source area for stress concentration to generate the main shock and the aftershocks. 相似文献
18.
Nicholas Deichmann John Clinton Stephan Husen Benjamin Edwards Florian Haslinger Donat Fäh Domenico Giardini Philipp Kästli Urs Kradolfer Stefan Wiemer 《Swiss Journal of Geoscience》2011,104(3):537-547
This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during
2010. During this period, 407 earthquakes and 85 quarry blasts were detected and located in the region under consideration.
With a total of only 19 events with ML ≥ 2.5, the seismic activity in the year 2010 was below the average over the previous 35 years. The two most noteworthy earthquakes
were the ML 3.4 Barrhorn event near Sankt Niklaus (VS) and the ML 3.0 event of Feldkirch, both of which produced shaking of intensity IV. 相似文献
19.
An intraplate earthquake of magnitude (M
c) 6.9 (Anon 2001a) struck Bhuj and the adjoining region of Kachchh in Gujarat on January 26th, 2001 at about 0316 hrs (GMT)
and was followed by a number of aftershocks. The epicentre of this earthquake was located at 23.4‡N and 70.28‡E close to the
Kachchh mainland fault. The intensity observed around the epicenter was X on the MSK scale. A study of 531 aftershocks, in
the magnitude range of 3.0–5.7, recorded at Vadodara Seismological Observatory till March 31st, 2001 has been carried out
and various statistical parameters calculated. The total energy released during the study period is calculated to be 8.2 ×
1014 joule. Sudden occurrence of the main shock without any foreshock in the same tectonic system is a unique feature of this
sequence. Theb- value (0.86), value of M0-M1 (1.2), high M1/M0 (0.89) and high value of the decay constanth (0.91), all support the tectonic origin of the present study. 相似文献
20.
We present JHKLM photometry obtained in 1984–2009 for the RCB stars UV Cas and SU Tau. No major fadings characteristic of RCB stars were detected
during the observations of UV Cas, while two events of this kind occurred for SU Tau. The observed flux and color-index variations
can be explained with a changing dust concentration in the line of sight, and possibly variations of the stellar temperature.
We use the measured fluxes, supplemented with observations in the intermediate IR, to compute spherically symmetric dust-shell
models for the stars. The mass-loss rate is estimated to be 1.7 × 10−6
M
⊙ yr−1 for UV Cas and 4.1 × 10−6
M
⊙ yr−1 for SU Tau. 相似文献