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1.
Gosselin Jeremy M. Dosso Stan E. Askan Aysegul Wathelet Marc Savvaidis Alexandros Cassidy John F. 《Journal of Seismology》2022,26(4):781-821
Journal of Seismology - Seismic site characterization attempts to quantify seismic wave behavior at a specific location based on near-surface geophysical properties, for the purpose of mitigating... 相似文献
2.
Geo-Characterization at selected accelerometric stations in Crete (Greece) and comparison of earthquake data recordings with EC8 elastic spectra 总被引：1，自引：0，他引：1
A. Savvaidis B. Margaris N. Theodoulidis V. Lekidis Ch. Karakostas C. Loupasakis D. Rozos P. Soupios M. -D. Mangriotis U. Dikmen Par. Tsangaratos E. Kokinou A. Vafidis Th. Rondoyanni I. Kalogeras S. Koutrakis A. Sarris N. Papadopoulos 《Central European Journal of Geosciences》2014,6(1):88-103
To estimate the seismic response according to Eurocode (EC8) and almost all other national codes, site conditions have to be properly characterized so that soil amplification and the corresponding peak ground motion can be calculated. In this work, different geophysical and geotechnical methods are combined in order to define the detailed ground conditions in selected sites of the Hellenic Accelerometric Network (HAN) in Crete. For this purpose, the geological information of the sites and shear wave velocity, calculated from surface wave measurements, is used. Additionally, ground acceleration data recorded through HAN have been utilized from intermediate depth earthquakes in the broader area of South Aegean Sea. Using the recorded ground motion data and the procedure defined in EC8, the corresponding elastic response spectrum is calculated for the selected sites. The resulting information is compared to the values defined in the corresponding EC8 spectrum for the seismic zone that includes the island of Crete. The comparison shows that accurate definition of ground type through geological, geotechnical and geophysical investigations is important. However, our current comparison focuses on the distribution of values rather than the absolute values of EC8-prescribed spectra, and the results should be considered in this context. 相似文献
3.
Palaeoseismological and archaeological analysis of a trench enabled us to estimate the Holocene slip rates on the East Helike Fault, flanking the south-western Gulf of Corinth. We recognized two major fault strands within the trench: the ‘north fault’ controls a succession of three colluvial wedges and the deposition of a 2.7 m thick sedimentary sequence. The ‘south fault’ controls the deposition of a 2.9-m thick brownish-red colluvium. Based on colluvial stratigraphy, radiocarbon dating of the sediments suggests that the slip rate was c. 0.3 mm yr−1 from 10 250 to c. 1400 bp , when it increased dramatically to c. 2.0 mm yr−1 after a strong earthquake event near 1400 bp . The faster slip rate evidently increased the sedimentation rate. 相似文献
4.
B.C. Papazachos A.S. Savvaidis C.B. Papazachos G.F. Karakaisis 《Journal of Seismology》2002,6(2):237-245
On the basis of growing evidence thatstrong earthquakes are preceded by a periodof accelerating seismicity of moderatemagnitude earthquakes, an attempt is madeto search for such seismicity pattern in NWAegean area. Accelerating seismic crustaldeformation has been identified in the areaof southern Albanides mountain range(border region between Greece, formerYugoslavia and Albania). Based on certainproperties of this activity and on itssimilarity with accelerating seismicdeformation observed before a strongearthquake which occurred in the sameregion on 26 May 1960 (M = 6.5), we canconclude that a similar earthquake may begenerated in the same region during thenext few years. This conclusion is inagreement with independent results whichhave been derived on the basis of the timepredictable model. 相似文献
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6.
Heinrich Hora George H. Miley Xiaoling Yang Paraskevas Lalousis 《Astrophysics and Space Science》2011,336(1):225-228
An extreme anomaly of laser-plasma interaction with petawatt-picosecond (PW-ps) pulses of very high contrast ratio for suppression
of relativistic self-focusing permitted a come-back of the Bobin-Chu side-on ignition of uncompressed deuterium-tritium (DT)
fusion fuel. The plasma blocks for the side-on ignition have to be produced by the well confirmed nonlinear force acceleration
which is about 100,000 times higher than thermo-kinetic fluid-dynamic acceleration for comparison with astrophysical cases.
It is essential that the dielectric plasma properties within the nonlinear force are used. Using the measured ion beam densities
above 1011 A s/cm2 the ignition mechanism needed numerical and theoretical studies of extremely strong shock phenomena. When extending these
results to the side-on ignition of uncompressed hydrogen-boron11 (HB11), surprisingly, the ignition by this shock mechanism
was only about 10 times more difficult than for DT in contrast to ignition by spherical laser driven compression using thermo-kinetic
conditions in which case HB11 ignition is 100,000 times more difficult than DT. 相似文献
7.
M. Bastani A. Savvaidis L.B. Pedersen T. Kalscheuer 《Journal of Applied Geophysics》2011,75(2):180-195
In order to gain a better understanding of the geometry of surface faults, five Controlled Source/Radio Magnetotelluric (CSRMT) profiles were measured across the Volvi basin, 45 km northeast of the city of Thessaloniki in Greece. The data were collected in two frequency ranges: a) 1–12.5 kHz using a remotely controlled double horizontal magnetic dipole transmitter (CSAMT measurements), and b) 15–250 kHz using the signal from distant radio transmitters (RMT measurements). The transition from the RMT band to the CSAMT band was smooth and continuous allowing us to combine both datasets for plane-wave modeling. The surface geology shows a predominantly 2D structure, and therefore we planned the survey into profiles perpendicular to the geological strike. We have used a 2D interpretation tool to model the data in TE, TM, TE + TM and determinant modes. Using a 4% error floor on the impedance, 2D resistivity models from inversion of the determinant data provide lower RMS data fits (4.2 and 1.2 for resistivity and phase, respectively) compared to the combined TE + TM data (4.4, 2.8, overall resistivity and phase, respectively). 2D inversion of the measured tensor data shows a sharp change in the depth to the top of resistive gneiss–schist basement that is overlain by a less resistive overburden at southern basin flanks. The change in depth to the bedrock is clearly seen in all 2D models along the measured profiles suggesting the existence of normal faults with strike directions of NE–SW to E–W. The 2D electrical resistivity models suggest that the bedrock deepens towards south-west. The resistivity models are also compared with the existing borehole information in the area and show a reasonable correlation. For example the sharp change of depth to the bedrock towards the center of the basin as seen in the resistivity models are also confirmed by the borehole data. 相似文献
8.
G.‐Akis Tselentis Paraskevas Paraskevopoulos Nikos Martakis 《Geophysical Prospecting》2010,58(5):845-859
We determine the attenuation structure of a three‐dimensional medium based on first pulse‐width measurements from microearthquake data. Ninety‐five microearthquakes from a seventy stations local network were considered in this study. Measurements of the first half cycle of the wave, the so‐called rise time τ were carried out on high quality velocity seismograms and inverted to estimate the P‐waves intrinsic quality factor Qp. The results of this investigation indicate that first pulse width data from a local microearthquake network permit retrieval with sufficient accuracy of the heterogeneous Qp structure. The inferred attenuation variability corresponds to the known geological formations in the region. 相似文献
9.
On the repeatability and consistency of three-component ambient vibration array measurements 总被引：1，自引：0，他引：1
Brigitte Endrun Matthias Ohrnberger Alexandros Savvaidis 《Bulletin of Earthquake Engineering》2010,8(3):535-570
Ambient vibration measurements with small, temporary arrays that produce estimates of surface wave dispersion have become
increasingly popular as a low-cost, non-invasive tool for site characterisation. An important requirement for these measurements
to be meaningful, however, is the temporal consistency and repeatability of the resulting dispersion and spatial autocorrelation
curve estimates. Data acquired within several European research projects (NERIES task JRA4, SESAME, and other multinational
experiments) offer the chance to investigate the variability of the derived data products. The dataset analysed here consists
of repeated array measurements, with several years of time elapsed between them. The measurements were conducted by different
groups in different seasons, using different instrumentations and array layouts, at six sites in Greece and Italy. Ambient
vibration amplitude spectra and locations of dominant sources vary between the two measurements at each location. Still, analysis
indicates that this does not influence the derived dispersion information, which is stable in time and neither influenced
by the instrumentation nor the analyst. The frequency range over which the dispersion curves and spatial autocorrelation curves
can be reliably estimated depends on the array dimensions (minimum and maximum aperture) used in the specific deployment,
though, and may accordingly vary between the repeated experiments. The relative contribution of Rayleigh and Love waves to
the wavefield can likewise change between repeated measurements. The observed relative contribution of Rayleigh waves is generally
at or below 50%, with especially low values for the rural sites. Besides, the visibility of higher modes depends on the noise
wavefield conditions. The similarity of the dispersion and autocorrelation curves measured at each site indicates that the
curves are stable, mainly determined by the sub-surface structure, and can thus be used to derive velocity information with
depth. Differences between velocity models for the same site derived from independently determined dispersion and autocorrelation
curves—as observed in other studies—are consequently not adequately explained by uncertainties in the measurement part. 相似文献
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