Dependence of theP-wave amplitude spectrum on focal depth

Summary Four spectral parameters, each of which reflects a certain spectral characteristic, are computed for 67 power spectra of earthquakes. The analyzed signals used in this work are theP-phases recorded by short-period, vertical-component seismographs.In correlating the values of the spectral parameters with the respective focal depths, a qualitative spectrum-depth relation is obtained. The most outstanding feature of the relationship thus computed, is a pronounced anomaly in the depth-range of 50–250 km. This is found to correlate rather well with the location of the low-velocity layer which many seismologists have shown to exist in the earth's upper mantle. With the aid of results obtained from experimental work on rock blasts, it is argued that the anomalous zone has more viscous character than the overlying and underlying media.On leave of absence from the Ministry of Oil and Minerals, Baghdad, Iraq     

Fourier analysis of the light curves of eclipsing variables,XIX

The aim of the present paper has been to generalize the methods previously developed for analysis of the light changes of eclipsing binary systems in the frequency-domain to cases in which the components of such systems revolve in eccentric orbits. It is shown that these methods can indeed be generalized to systems with eccentric orbits provided that the light momentsA _2m deduced from such eclipses are suitably re-defined in terms of the true, rather than mean, anomaly in the relative orbit; and that due attention is paid to the unit of length in terms of which the fractional radii of the two stars are expressed. When this is done the Fourier methods continue to be applicable to all types of eclipses exhibited by eccentric binary systems — whether these are occultations or transits; total, annular or partial.An application of these methods to practical cases has been postponed for a subsequent communication.     

Tectonic control on the morphology of the subcircular structure of El Mdaouar (Saharan Atlas,Algeria): insights from geological and remote sensing data

El Mdaouar subcircular structure is located in the eastern Saharan Atlas (Algeria) at 35° 05′ N and 4° 19′ 30″ E, about 20 km southwest of the town of Bou Saada. Its diameter is about 3.2 km and shows a raised rim that stands high above the surrounding terrain. We have carried out a combining remote sensing (Landsat 8 OLI image and Shuttle Radar Topography Mission (SRTM) data) and geological field investigation of the El Mdaouar subcircular structure in order to study its morphology and to determine its origin. In the absence of evidence of magmatism, diapirism, and impact on this structure, a tectonic deformation is the most likely in the origin of this subcircular feature. The counterclockwise rotational motion of the layers explains the morphology of the structure. This rotational motion is probably the result of a combination of the movement of the faults which pass through the structure, in particular two NE-SW strike-slip faults and a NW-SE fault, which marks the eastern limit of the El Mdaouar structure. The NE-SW trending of the structure indicates a NW-SE compressional event, which corresponds to that of the Atlasic phase. This event occurred in the Late Eocene (35 Ma), which is the best estimation of the age of the El Mdaouar structure.     

Estimation of daily reference evapotranspiration with limited climatic data using machine learning approaches across different climate zones in New Mexico

Theoretical and Applied Climatology - Reference evapotranspiration (ET0) is a major factor for water resource management. Although the FAO Penman–Monteith model is the highly recommended for...     

Impact of Land use Changes on Landslides Occurrence in Urban Area: The Case of the Constantine City (NE Algeria)

Geotechnical and Geological Engineering - The city of Constantine (NE Algeria), the third largest city of the country (2.374 inhabitants/km2) is facing frequent damaging landslides that constitute...