Anomalous Seismo-Electromagnetic Emission Related with Seismic Waves
This paper reports the rare high intensity electromagnetic pulses associated with earthquakes, with different to atmospherics spectrum signature. On the base of actual data records, the cases of generation of anomalous seismo-electromagnetic emission founded. These natural sub-millisecond electromagnetic pulses have been associated with passage of seismic waves through the place of electromagnetic field observations. The waveform, spectrum and time characteristics of sub-millisecond electromagnetic pulses have been described. The deeper the source the lower frequencies can be observed in the spectrum on the surface.
Airborne electronic equipment immunity to the very low frequency electromagnetic field influence (civil aviation standards problems)
Airborne electronic equipment reliable operation is critical in ensuring flight safety. The civil aviation RTCA/DO-160E and EUROCAE/ED-14E standard procedures and environmental test criteria for testing airborne equipment aimed on the aircraft onboard electromagnetic emission sources. Taking in an account the possibility of external very low frequency electromagnetic field influence on the electronic onboard equipment it is possible to find a number of severe problems. Analyses of unspecified frequency bands and requirements for the testing aircraft electronic onboard equipment were conducted in this paper.
The role of early lithification in development of chalky porosity in calcitic micrites: Upper Cretaceous chalks, Egypt
Abstract Petrological and geochemical examination of Upper Cretaceous chalks from the Abu Roash area and Bahariya Oasis (Egypt) provide insights into factors which control porosity development in fine-grained calcitic carbonates. Petrological studies indicate that primary skeletal fabrics of coccoliths and foraminifera in micrites of Abu Roash are well preserved. In contrast, primary skeletal fabrics of the Bahariya Oasis chalks are pervasively altered. Geochemical analysis of these chalks reveals a striking contrast in composition. The high porosity chalks at Bahariya Oasis have depleted isotopic values ( δ 13 C = −5.0‰, δ 18 O = −8.9‰ PDB ) and low concentrations of trace elements (Sr and Na). In contrast, the low porosity chalks at Abu Roash are less depleted in terms of their isotopic values ( δ 13 C = 1.0‰, δ 18 O = −4.0‰ ) and possess elevated concentrations of Sr, Na, Fe and Zn. Importantly, fracture and collapse veins, present only at Abu Roash, are filled with calcite whose δ18O value is coincident with that of altered micrites at Bahariya Oasis. The lithic fragments cemented by this calcite, however, retain compositions identical to other lithified limestones at Abu Roash. Differences in fabric and chemistry of the pelagic marine micrites observed between Abu Roash and Bahariya Oasis reflect the degree of early lithification and compaction prior to exposure and meteoric diagenetic alteration associated with regional Late Cretaceous/pre-Eocene subaerial unconformity.