Age of the Chibit Glaciation in Gornyi Altai

Doklady Earth Sciences - New results of Optically-Stimulated Luminescence (OSL) dating that make it possible to clarify the age of the Chibitskii glaciation in the Altai Mountains are reported....     

New data on the most ancient early quaternary glaciation in Gornyi Altai

The data presented in this work introduce substantial corrections into the Upper Cenozoic stratigraphy and geological history of Gornyi Altai. They provide evidence for the most ancient Early Pleistocene glaciation in this region. This follows from finds of faceted boulders buried in the Bashkaus Formation. Pale-omagnetic investigations revealed in the latter a wide zone of negative polarity corresponding to the Matuyama Chron in the magnetostratigraphic scale and made it possible to correlate the formation with the Lower Pleistocene in the standard stratigraphic scale. It is shown that global cooling at the beginning of the Quaternary Period stimulated development of glaciation on the southern slope of the Kuraiskii Range exceeding in size its present-day scale.     

Lithology and stratigraphy of the Ordovician facies complexes of Gornyi Altai

In the Ordovician time, the transform margin of the Gornyi Altai region consisted of two bathymetric stages: (1) shelf and upper parts of continental slope; (2) foothills and lower parts of continental slope. The first stage includes the shallow-water facies complexes (terrigenous and terrigenous-carbonate schlieren and variegated flyschoid), while the second stage is composed of deep-water (black shale terrigenous) and subflysch gray (carbonate terrigenous) complexes. Model series of the facies complexes established in our work should be taken into account during the geodynamic analysis of fold zones.     

Age of Glacial and Fluvioglacial Deposits of the Chibit Glaciocomplex in Gornyi Altai

Doklady Earth Sciences - The aerial stratotype of the Chibit Glaciation in a stratigraphic chart of Quaternary deposits of the Altai–Sayan Mountains, which corresponds to the Last Glacial...     

The First Data on Late Pleistocene Ostracods from the Kurai Depression (Gornyi Altai)

Doklady Earth Sciences - In the sections of Late Pleistocene deposits of the Kurai Depression of Gornyi Altai studied, an ostracod assemblage, including Leucocythere sp. 1, L. sp. 2, Leucocythere...     

Excess of Rare-Earth Elements in Plant Foods as a Cause of Geophagy among Ungulates in Gornyi Altai

Doklady Earth Sciences - Geological and hydrobiogeochemical studies carried out in two areas of active geophagy among herbivorous animals in the area of Teletskoye Lake in the Altai Mountains...     

Estimation from incomplete data files based on magnitude-frequency relation for earthquakes

The problem of incorporating the available seismological information provided by the major events of the historical catalog with those for the short period of instrumental data is investigated. Assuming that the frequency-magnitude law of Gutenberg and Richter is valid for both periods, an estimation procedure for the main parameter of this law and the rate of earthquake occurrence for historical period is presented. Application of the proposed method is demonstrated, using both real and simulated data. An extension to allow for variable quality of complete data with different magnitude values is also included.     

漳华龙地区地磁异常与地震对应关系分析

选取龙岩台的地磁资料,总结漳华龙地区震例,用压磁效应、感应磁效应等理论解释、分析地震与地磁异常的对应关系。结果表明,不同类型的地震,在孕育地震的不同时期,有不同的地质构造运动,产生的地磁异常也是不尽相同的。地磁异常的显著程度不仅与地震的应力降、震级、以及岩石的磁性有关,还和震源机制关系很大。     

Multifractal analysis of earthquakes in Kumaun Himalaya and its surrounding region

Himalayan seismicity is related to continuing northward convergence of Indian plate against Eurasian plate. Earthquakes in this region are mainly caused due to release of elastic strain energy. The Himalayan region can be attributed to highly complex geodynamic process and therefore is best suited for multifractal seismicity analysis. Fractal analysis of earthquakes (mb ?? 3.5) occurred during 1973?C2008 led to the detection of a clustering pattern in the narrow time span. This clustering was identified in three windows of 50 events each having low spatial correlation fractal dimension (D _C ) value 0.836, 0.946 and 0.285 which were mainly during the span of 1998 to 2005. This clustering may be considered as an indication of a highly stressed region. The Guttenberg Richter b-value was determined for the same subsets considered for the D _C estimation. Based on the fractal clustering pattern of events, we conclude that the clustered events are indicative of a highly stressed region of weak zone from where the rupture propagation eventually may nucleate as a strong earthquake. Multifractal analysis gave some understanding of the heterogeneity of fractal structure of the seismicity and existence of complex interconnected structure of the Himalayan thrust systems. The present analysis indicates an impending strong earthquake, which might help in better hazard mitigation for the Kumaun Himalaya and its surrounding region.     

Long-term prediction of intermediate depth earthquakes in the southern Aegean region based on a time-predictable model

Repeat times of strong intermediate depth (60 km h 180 km) earthquakes have been determined by the use of instrumental and historical data for six seismogenic sources in the Benioff zone of the southern Aegean area. For four of these sources, at least two interevent times (three mainshocks) are available for each source. By using the repeat times for these four sources, the following relation has been determined: logT _t = 0.20M _min + 0.19M _p +a, whereT _t is the repeat time (in years),M _min the surface wave magnitude of the smallest earthquake considered,M _p the magnitude of the preceding mainshock and a parameter which varies from source to source. A multilinear correlation coefficient equal to 0.91 was determined for this relation, which indicates that the time predictable model holds to a satisfactory degree for the strong mainshocks of intermediate focal depth in the southern Aegean.By assuming that the ratioT/T _t, whereT is the observed andT _t the calculated repeat time, follows a lognormal distribution, the conditional probabilities for the occurrence of strong (M _s 6.5) and very strong (M _s 7.5) earthquakes during the period 1991–2001 in these four seismogenic sources have been calculated. These probabilities are very high (P > 0.9) for the strong and high (P > 0.5) for the very strong intermediate depth earthquakes which occur in the three sources of the shallower (h < 100 km) part of the Benioff zone where coupling occurs between the front parts of the Mediterranean lithosphere (downgoing) and the Aegean lithosphere.     

Estimation of the waiting time distributions of earthquakes

Whether the earthquake occurrences follow a Poisson process model is a widely debated issue. The Poisson process model has great conceptual appeal and those who rejected it under pressure of empirical evidence have tried to restore it by trying to identify main events and suppressing foreshocks and aftershocks. The approach here is to estimate the density functions for the waiting times of the future earthquakes. For this purpose, the notion of Gram-Charlier series which is a standard method for the estimation of density functions has been extended based on the orthogonality properties of certain polynomials such as Laguerre and Legendre. It is argued that it is best to estimate density functions in the context of a particular null hypothesis. Using the results of estimation a simple test has been designed to establish that earthquakes do not occur as independent events, thus violating one of the postulates of a Poisson process model. Both methodological and utilitarian aspects are dealt with.     

The first dating of strong Holocene earthquakes in Gorny Altai using long-term tree-ring chronologies

We present the first results of application of long-term tree-ring chronologies for dating seismically triggered rockfalls and determining the upper age of Holocene rockfalls in southeastern Altai. Based on the results of seismic dendrochronological analysis, dating of penetrating wood injuries is proposed and tested, and the criterion for the distinguishing of seismically triggered rockfalls among slope processes of climatic nature is formulated. An earlier unknown strong earthquake of 1532 has been recognized; its traces are dated by the radiocarbon method. Based on the new data and calibration of earlier radiocarbon dates, the recurrence period of strong earthquakes in the southeastern Altai is refined.     

年最大洪水两变量联合分布研究

采用Von Mises分布拟合年最大洪水发生时间的概率分布,采用皮尔逊Ⅲ型分布拟合年最大洪水量级的概率分布,选用能够较好反映年最大洪水发生时间和量级之间相关结构的Gumbel Archimedean Copula函数,建立两变量联合分布,并定义和分析条件频率、联合频率和两变量重现期.实例分析表明年最大洪水的两变量分布拟合较好,可挖掘更多信息,为洪水设计分析提供了一条新的途径.