Comment on the paper “The Relationship between Multifractal and Entropy Properties of Seismic Noise in Kamchatka and Irregularity of the Earth’s Rotation” by A.A. Lyubushin,G.N. Kopylova,and Yu.K. Serafimova

Izvestiya, Physics of the Solid Earth - Abstract—In my comment on the paper by A.A. Lyubushin, G.N. Kopylova, and Yu.K. Serafimova, I focus on the problem of legitimacy of seismological data...     

Deep Structure of the Swiss Alps,Results of NRP 20. Edited by O. A. Pfiffner,P. Lehner,P Heitzmann,St. Müller and A. Steck,Birkhauser Verlag,Basel 1997, 380pp.

Studia Geophysica et Geodaetica -     

Revised determination of the paleointensity in the cretaceous from the collection of A.S. Bol’shakov and G.M. Solodovnikov

A large volume of data on the paleointensity H _an obtained by A.S. Bol’shakov and G.M. Solodovnikov is ignored in modern reconstructions because the authors did not indicate whether they used the check-point procedure for the detection of chemical alterations in rocks associated with determination of H _an. The paper presents new values of H _an determined by the Thellier-Coe method with the use of the checkpoint procedure from samples of the Armenian collection of Cretaceous rocks used in published studies of Bol’shakov and Solodovnikov. The new results are close to the published ones and point to a small value of the geomagnetic field in the Cretaceous, thereby corroborating Bol’shakov-Solodovnikov’s hypothesis on a low paleofield in the Mesozoic. Our study of samples of the collection studied confirms the reliability of Bol’shakov-Solodovnikov’s determinations of H _an.     

Reply to Comment by V. Vavryčuk on “Analysis of the State of Stress During the 1997 Swarm in the Western Bohemia” by A. Slancová and J. Horálek

Studia Geophysica et Geodaetica -     

Evidence of earthquakes triggered by the tidal force of the sun and the moon——On the temporal characteristics of the earthquakes in Xingtai,Hejian and Tangshan

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Commentary on “Earthquake Depths in the Crimea–Black Sea Region” by V.E. Kulchitsky,B.G. Pustovitenko and V.A. Svidlova

It is well known that the results of determining earthquake parameters depend to a large extent on data processing algorithms and velocity models of the seismic wave propagation medium used in solving hypocenter problems. In 1992, V.Yu. Burmin developed a hypocentric algorithm that minimizes the functional of distances between the points corresponding to the theoretical and observed travel times of seismic waves from an earthquake source to recording stations. The determination of the coordinates of earthquake hypocenters in this case is much more stable than for the commonly used minimization of the functional of discrepancies in the seismic wave arrival times at a station. Using this algorithm and the refined velocity model of the medium, V.Yu. Burmin and L.A. Shumlyanskaya reinterpreted the earthquake parameters for the Crimea–Black Sea region. The most important result of this reinterpretation was the conclusion about the occurrence of deep earthquakes with a source depth of more than 60 km in the region. This result contradicts the conventional beliefs about the seismicity of the region and therefore aroused strong criticism from experts directly involved in compiling the existing catalogs of regional earthquakes. These comments and criticisms are presented by V.E. Kulchitsky with coauthors in a work published in this issue of the journal. In the present paper, we analyze the comments in detail and respond. In particular, we show that the previously used methods of seismic data processing made it highly unlikely by default that deep earthquakes would appear in the results. As an example, we refer to the use of travel-time curves for depths down to 35 km. It is clear that deep earthquakes could not have been found with this approach.     

Assessment of the possibility of using E. A. Ponomarev’s magnetospheric substorm model to analyze geomagnetic disturbances during the magnetic storms of December 14 and 15, 2006

Spatial distributions of pressure and fluxes of precipitating magnetospheric plasma particles were constructed for the strong magnetic storm of December 14 and 15, 2006. The calculations were performed using a model developed by E.A. Ponomarev. Geotail and ACE satellite data were used to specify realistic initial and boundary conditions. The model results were compared with the spatial distribution of the field of geomagnetic disturbances recorded by ground-based magnetic observatories during the storm. The results show that the model (in its current form) provides good agreement between latitudinal displacements of electron precipitations and auroral electrojets but fails to reflect their longitudinal structure. The model fails to yield the strong westward electrojet observed by all auroral zone observatories during the main phase of the magnetic storm.     

A re-appraisal of the stratigraphy and volcanology of the Cerro Galán volcanic system,NW Argentina

From detailed fieldwork and biotite ⁴⁰Ar/³⁹Ar dating correlated with paleomagnetic analyses of lithic clasts, we present a revision of the stratigraphy, areal extent and volume estimates of ignimbrites in the Cerro Galán volcanic complex. We find evidence for nine distinct outflow ignimbrites, including two newly identified ignimbrites in the Toconquis Group (the Pitas and Vega Ignimbrites). Toconquis Group Ignimbrites (~5.60–4.51 Ma biotite ages) have been discovered to the southwest and north of the caldera, increasing their spatial extents from previous estimates. Previously thought to be contemporaneous, we distinguish the Real Grande Ignimbrite (4.68 ± 0.07 Ma biotite age) from the Cueva Negra Ignimbrite (3.77 ± 0.08 Ma biotite age). The form and collapse processes of the Cerro Galán caldera are also reassessed. Based on re-interpretation of the margins of the caldera, we find evidence for a fault-bounded trapdoor collapse hinged along a regional N-S fault on the eastern side of the caldera and accommodated on a N-S fault on the western caldera margin. The collapsed area defines a roughly isosceles trapezoid shape elongated E-W and with maximum dimensions 27 × 16 km. The Cerro Galán Ignimbrite (CGI; 2.08 ± 0.02 Ma sanidine age) outflow sheet extends to 40 km in all directions from the inferred structural margins, with a maximum runout distance of ~80 km to the north of the caldera. New deposit volume estimates confirm an increase in eruptive volume through time, wherein the Toconquis Group Ignimbrites increase in volume from the ~10 km³ Lower Merihuaca Ignimbrite to a maximum of ~390 km³ (Dense Rock Equivalent; DRE) with the Real Grande Ignimbrite. The climactic CGI has a revised volume of ~630 km³ (DRE), approximately two thirds of the commonly quoted value.