Pure and Applied Geophysics

article

Seismological Evidence of Active Faulting in the Tendaho Rift (Afar Triangle, Ethiopia)

S. Gresta, D. Patan, A. Daniel, L. Zan, more

Pure and Applied Geophysics > 1997 > 149 > 2 > 357-374

AbstractA temporary network has been used to study the seismic activity in the central-northern part of the Tendaho Rift (Afar Triangle, Ethiopia). Small size earthquakes (M 2.5) characterize the seismicity during the time interval 19931994 when the seismic array was operating. Shocks are mainly located in the central part of the Tendaho rift and their epicentral distribution highlights a remarkable...

article

Enhancement of Signal-to-noise Ratio in Natural-source Transient Magnetotelluric Data with Wavelet Transform

Y. Zhang, K. V. Paulson

Pure and Applied Geophysics > 1997 > 149 > 2 > 405-419

AbstractFor audio-frequency magnetotelluric surveys where the signals are lightning-stroke transients, the conventional Fourier transform method often fails to produce a high quality impedance tensor. An alternative approach is to use the wavelet transform method which is capable of localizing target information simultaneously in both the temporal and frequency domains. Unlike Fourier analysis that...

article

Numerical Modelling of Block-structure Dynamics: Application to the Vrancea Region

G. F. Panza, A. A. Soloviev, I. A. Vorobieva

Pure and Applied Geophysics > 1997 > 149 > 2 > 313-336

AbstractA seismically active region is modelled as a system of absolutely rigid blocks separated by infinitely thin plane faults. The interaction of the blocks along the fault planes and with the underlying medium is viscous-elastic. The system of blocks moves as a consequence of prescribed motion of the boundary blocks and of the underlying medium. When, for some part of a fault plane the stress...

article

Book Reviews

Pure and Applied Geophysics > 1997 > 149 > 2 > 421-445

article

Influence of Nonlinear Processes in Seismic Foci on Released Energy

V. Aksenov, T. Lokajiek

Pure and Applied Geophysics > 1997 > 149 > 2 > 337-355

AbstractThe results of the frequency analysis of seismoacoustic elastic waves radiated from the loaded rock sample source models and of rock bursts records are presented. For both categories of study the fundamental symptoms of nonlinear processes in seismic foci were found and demonstrated. Namely, the wave-field modulation (satellites in the spectra), forced synchronisation (spectra simplification...

article

Multifractal Approach to Time Clustering of Earthquakes. Application to Mt. Vesuvio Seismicity

C. Codano, M. L. Alonzo, G. Vilardo

Pure and Applied Geophysics > 1997 > 149 > 2 > 375-390

AbstractThe clustering structure of the Vesuvian earthquakes occurring is investigated by means of statistical tools: the inter-event time distribution, the running mean and the multifractal analysis. The first cannot clearly distinguish between a Poissonian process and a clustered one due to the difficulties of clearly distinguishing between an exponential distribution and a power law one. The running...

article

Electrical and Thermal Anomalies in the Central Andean Subduction Zone

A. Favetto, P. Martinelli, A. Osella

Pure and Applied Geophysics > 1997 > 149 > 2 > 391-404

AbstractAn enhancement of the electrical conductivity in the upper layers in the subduction zones of southern Peru and northern Argentina is found by analyzing the solar quiet geomagnetic variations. This feature appears in a zone associated with large subduction angles. In this region high values of heat flow have been measured, therefore a one-dimensional thermal model is proposed using regional...

article

Ground Motion Modeling for Seismic Hazard Analysis in the Near-source Regime: An Asperity Model

C.-C. P. Tsai

Pure and Applied Geophysics > 1997 > 149 > 2 > 265-297

AbstractA new, yet simple, method using the asperity model to estimate ground motion in the near-source regime for probabilistic seismic hazard analyses is proposed in this study. This near-source model differs from conventional empirical attenuation equations. It correlates peak ground motions with the local contributing source in terms of the static stress drop released non-uniformly on the causative...

article

The First Version of the Amax(MW,R) Relationship for Kamchatka

A. A. Gusev, E. I. Gordeev, E. M. Guseva, A. G. Petukhin, more

Pure and Applied Geophysics > 1997 > 149 > 2 > 299-312

AbstractTo estimate for the first time the typical relation between peak acceleration Amax, moment magnitude MW and hypocentral distance R for Kamchatka, 101 analog strong motion records for 19691993 were employed as the initial data set. Records of acceleration and velocity meters were obtained at 15 rock to medium-ground Kamchatkan sites from 33 earthquakes with MW = 4.57.8, at R = 30250km. Amax...

article

Subhorizontal Layering in the Lower Crust and its Tectonic Significance in the Narmada-Son-Region, India

P. R. Reddy, D. M. Mall, A. S. S. S. R. S. Prasad

Pure and Applied Geophysics > 1997 > 149 > 3 > 525-540

AbstractComparison of deep seismic sounding (DSS) results of different profiles across the Narmada-Son Lineament (NSL), India indicates the anomalous nature of the crust along the Ujjain-Ma han profile. Forward travel time and synthetic seismogram modeling, using normalized record sections of refraction and wide angle reflection data acquired along the Ujjain-Mahan deep seismic sounding profile across...

article

Book Reviews

Pure and Applied Geophysics > 1997 > 149 > 3 > 623-639

article

Analysis of the Temporal Occurrence of Seismicity at Deception Island (Antarctica). A Nonlinear Approach

A. M. Correig, M. Urquizu, J. Vila, J. Marti

Pure and Applied Geophysics > 1997 > 149 > 3 > 553-574

AbstractDeception Island is characterized by small magnitude local events with constant energy flux and very low stress drop. To obtain information about its origin, an interevent time series of 546 events, corresponding to an observational period of two month, has been analyzed. From a statistical point of view, data satisfies a Weibull distribution and presents clustering. A rescaled range analysis...

article

The Frequency Dependence of Harmonic Fluid Flow Through Networks of Cracks and Pores

Y. Bernab

Pure and Applied Geophysics > 1997 > 149 > 3 > 489-506

AbstractThe dynamic permeability k() of heterogeneous networks of cracks, tubes and spheres, was determined by numerically simulating the harmonic flow of an interstitial fluid for a wide range of frequencies. For comparison with previous works, this procedure was applied to the 100 network realizations used in Bernab (1995). In most cases, the calculated frequency dependence of the real and imaginary...

article

Rayleigh Wave Group Velocity Tomography of Siberia, China and the Vicinity

F. T. Wu, A. L. Levshin, V. M. Kozhevnikov

Pure and Applied Geophysics > 1997 > 149 > 3 > 447-473

AbstractRayleigh waves are used in a tomographic inversion to obtain group velocity maps of East Asia (40 E160 E and 20 N70 N). The period range studied is 30 to 70 seconds. Seismograms used for this study were recorded at CDSN stations, at a temporary broadband seismic array in Tibet, at several SRO stations, and Kirnos-equipped stations established in Asia by the former Soviet Union, in Siberia,...

article

Rock Properties and Seismic Attenuation: Neural Network Analysis

F. K. Boadu

Pure and Applied Geophysics > 1997 > 149 > 3 > 507-524

AbstractUsing laboratory data, the influence of rock parameters on seismic attenuation has been analyzed using artificial neural networks and regression models. The predictive capabilities of the neural networks and multiple linear regresssion were compared. The neural network outperforms the multiple linear regression in predicting attenuation values, given a set of input of rock parameters. The...

article

Lateral Variations of Lg Coda Q in Southern Mexico

J. Yamamoto, L. Quintanar, R.B. Herrmann, C. Fuentes

Pure and Applied Geophysics > 1997 > 149 > 3 > 575-599

AbstractBroad band digital three-component data recorded at UNM, a GEOSCOPE station, were used to estimate Lg coda Q for 34 medium size (3.9 mb 6.3) earthquakes with travel paths laying in different geological provinces of southern Mexico in an effort to establish the possible existence of geological structures acting as wave guides and/or travel paths of low attenuation between the Pacific coast...

article

Synthetic Seismograms for a Layered Earth Geological Model Using the Absorption and Dispersion Phenomena

A. Ram, J. P. Narayan

Pure and Applied Geophysics > 1997 > 149 > 3 > 541-551

AbstractAn algorithm has been developed to compute the dispersive and dissipative seismic response using FUTTERMANS (1962) third attenuation-dispersion relationship. In the computation, frequency-dependent velocity and quality factor Q have been used but in the case of the nondispersive synthetic seismogram, frequency-independent velocity has been used. The models parameters are density, phase velocity,...

article

Tectonic and Kinematic Regime along the Northern Caribbean Plate Boundary: New Insights from Broad-band Modeling of the May 25, 1992, Ms = 6.9 Cabo Cruz, Cuba, Earthquake

J. Perrot, E. Calais, B. Mercier de Lpinay

Pure and Applied Geophysics > 1997 > 149 > 3 > 475-487

AbstractOn May 25th, 1992, an Ms = 6.9 earthquake occurred off the southwestern tip of Cuba, along the boundary between the Caribbean and North American plates. This earthquake was the largest to strike southern Cuba since 1917 and the largest ever recorded in that region by global seismic networks. It is therefore a key element for our understanding of the tectonic and kinematic regime along the...

article

The Role of Radiative Transfer in Maintaining the Indian Summer Monsoon Circulation

M. J. Leach, S. Raman, U. C. Mohanty, R. V. Madala

Pure and Applied Geophysics > 1997 > 149 > 3 > 601-622

AbstractThe radiative-convective feedback and land-sea thermal forcing play significant roles in maintenance of the summer monsoon circulation over the Indian sub-continent. In this study, the role of radiative transfer in maintaining the monsoon circulation is examined with numerical sensitivity experiments. For this purpose, a sixteen layer primitive equation limited area model is used to perform...

article

Book Reviews

Pure and Applied Geophysics > 1997 > 149 > 4 > 809-834

INFONA - science communication portal

Pure and Applied Geophysics

Seismological Evidence of Active Faulting in the Tendaho Rift (Afar Triangle, Ethiopia)

Enhancement of Signal-to-noise Ratio in Natural-source Transient Magnetotelluric Data with Wavelet Transform

Numerical Modelling of Block-structure Dynamics: Application to the Vrancea Region

Book Reviews

Influence of Nonlinear Processes in Seismic Foci on Released Energy

Multifractal Approach to Time Clustering of Earthquakes. Application to Mt. Vesuvio Seismicity

Electrical and Thermal Anomalies in the Central Andean Subduction Zone

Ground Motion Modeling for Seismic Hazard Analysis in the Near-source Regime: An Asperity Model

The First Version of the Amax(MW,R) Relationship for Kamchatka

Subhorizontal Layering in the Lower Crust and its Tectonic Significance in the Narmada-Son-Region, India

Book Reviews

Analysis of the Temporal Occurrence of Seismicity at Deception Island (Antarctica). A Nonlinear Approach

The Frequency Dependence of Harmonic Fluid Flow Through Networks of Cracks and Pores

Rayleigh Wave Group Velocity Tomography of Siberia, China and the Vicinity

Rock Properties and Seismic Attenuation: Neural Network Analysis

Lateral Variations of Lg Coda Q in Southern Mexico

Synthetic Seismograms for a Layered Earth Geological Model Using the Absorption and Dispersion Phenomena

Tectonic and Kinematic Regime along the Northern Caribbean Plate Boundary: New Insights from Broad-band Modeling of the May 25, 1992, Ms = 6.9 Cabo Cruz, Cuba, Earthquake

The Role of Radiative Transfer in Maintaining the Indian Summer Monsoon Circulation

Book Reviews

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