The P–SV Decoupling Condition and Its Bearing on the Structure of the Earth     

A. Ben-Menahem  M. Weinstein 《Geophysical Journal International》1970,21(2):131-135

  相似文献   

Changes in the Earth's Inertia Tensor due to Earthquakes by MacCullagh's formula     

Moshe Israel  Ari Ben-Menahem 《Geophysical Journal International》1975,40(2):305-307

  相似文献   

Electric field at the seafloor due to a two-dimensional ionospheric current     

Risto J. Pirjola  Ari T. Viljanen  & David H. Boteler 《Geophysical Journal International》2000,140(2):286-294

The relation between the seafloor electric field and the surface magnetic field is studied. It is assumed that the fields are created by a 2-D ionospheric current distribution resulting in the E-polarization. The layered earth below the sea water is characterized by a surface impedance. The electric field at the seafloor can be expressed either as an inverse Fourier transform integral over the wavenumber or as a spatial convolution integral. In both integrals the surface magnetic field is multiplied by a function that depends on the depth and conductivity of the sea water and on the properties of the basement. The fact that surface magnetic data are usually available on land, not at the sea surface, is also considered. Test computations demonstrate that the numerical inaccuracies involved in the convolution method are negligible. The theoretical equations are applied to calculate the seafloor electric fields due to an ionospheric line current or associated with real magnetic data collected by the IMAGE magnetometer array in northern Europe. Two different sea depths are considered: 100 m (the continental shelf) and 5 km (the deep ocean). It is seen that the dependence of the electric field on the oscillation period is weaker in the 5 km case than for 100 m.  相似文献   

Green's tensor and radiation patterns of point sources in general anisotropic inhomogeneous elastic media   总被引：2，自引：0，他引：2  

Ari Ben-Menahem  Richard L. Gibson Jr  Arcangelo G. Sena 《Geophysical Journal International》1991,107(2):297-308

  相似文献   

The Saddle-Point Approximation for Damped Surface Waves     

Ari Ben-Menahem  Harold Jeffreys 《Geophysical Journal International》1971,24(1):1-2

  相似文献   

Generalized Multipolar Ray Theory for Surface and Shallow Sources     

Moshe Vered  Ari Ben-Menahem 《Geophysical Journal International》1976,45(1):195-198

  相似文献   

From mass‐wasting to slope stabilization – putting constrains on a tectonically induced transition in slope erosion mode: a case study in the Judea Hills,Israel     

Uri Ryb  Ari Matmon  Naomi Porat  Oded Katz 《地球表面变化过程与地形》2013,38(6):551-560

Calcrete‐coated remnants of landslide debris and alluvial deposits are exposed along the presently stable hillslopes of the Soreq drainage, Judea Hills, Israel. These remnants indicate that a transition from landslide‐dominated terrain to dissolution‐controlled hillslope erosion had occurred. This transition possibly occurred due to the significant decrease in tectonic uplift during the late Cenozoic. The study area is characterized by sub‐humid Mediterranean climate. The drainage hillslopes are typically mantled by thick calcrete crusts overlying Upper Cretaceous marine carbonate rocks. Using TT‐OSL dating of aeolian quartz grains incorporated in the calcrete which cements an ancient landslide deposit, we conclude that incision of ~100 m occurred from 1056 ± 262 to 688 ± 86 ka due to ~0·3° westward tilt of the region; such incision invoked high frequency of landslide activity in the drainage. The ages of a younger landslide remnant, alluvial terrace, and alluvial fan, all situated only a few meters above the present level of the active streambed, range between 688 ± 86 ka and 244 ± 25 ka and indicate that since 688 ± 86 the Soreq base level had stabilized and that landslide activity decreased significantly by the middle Pleistocene. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

A review of progress in modelling of induced geoelectric and geomagnetic fields with special regard to induced currents     

Alan W.P. Thomson  Allan J. McKay  Ari Viljanen 《Acta Geophysica》2009,57(1):209-219

The Earth’s lithosphere and mantle respond to Space Weather through time-varying, depth-dependent induced magnetic and electric fields. Understanding the properties of these electromagnetic fields is a key consideration in modelling the hazard to technological systems from Space Weather. In this paper we review current understanding of these fields, in terms of regional and global-scale geology and geophysics. We highlight progress towards integrated European-scale models of geomagnetic and geoelectric fields, specifically for the purposes of modelling geomagnetically induced currents in power grids and pipelines.  相似文献   

Early angiosperm diversification: evidence from southern South America     

Sergio Archangelsky  Viviana Barreda  Mauro G. Passalia  Maria Gandolfo  Mercedes Prámparo  Edgardo Romero  Rubén Cúneo  Alba Zamuner  Ari Iglesias  Magdalena Llorens  Gabriela G. Puebla  Mirta Quattrocchio  Wolfgang Volkheimer 《Cretaceous Research》2009,30(5):1073-1082

In this report, we analyze the angiosperm fossil record (micro- and megafossil) from the central and southern basins of Argentina, southern South America, deposited between the late Barremian (128.3 Ma) to the end of the Coniacian (85.8 Ma). Based on this analysis, three major stages in the evolution of the angiosperms in the southernmost region of South America are established as follows: the late Barremian–Aptian, the latest Aptian-earliest Albian, and the middle Albian- Coniacian. The comparison between our fossil data set and those from Australia, North America, Asia and Europe suggest that the evolution and diversification of the angiosperms at mid and high latitudes in both hemispheres occurred roughly synchronously.  相似文献   

Latent Heat Flux from Small Sheltered Lakes   总被引：1，自引：0，他引：1  

Ari Venäläinen  Martti Heikinheimo  Tapio Tourula 《Boundary-Layer Meteorology》1998,86(3):355-377

The dependency of the latent heat flux on the over-water fetch on lakes surrounded by tall, dense forest was studied by making use of measurements made on two different-sized lakes. The measurements were made during the NOPEX (Northern Hemisphere Climate-Processes Land Surface Experiment) field campaign. It was found that, in the case of a typical Scandinavian lake with a size of less than 10 km², the latent heat flux will increase as a function of over-water fetch due to the increase of wind speed and in spite of the increased air humidity. This also has implications on area-averaged fluxes: when two lakes having similar shorelines, lake water temperatures and solar radiation conditions are compared, then the evaporation per unit area is smaller from the smaller lake. When the lakes are large, with fetches of several kilometres, then the significance of sheltering is small. If point measurements are used for the estimation of area-averaged latent heat fluxes from lakes with short fetches and forested shorelines then the distance of the measuring site from the shoreline should be taken into account, otherwise errors of tens of percent may occur.  相似文献