On Some Strong Earthquakes in Central Asia in the Second Half of the 19th Century
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ome Strong Earthquakes in Central Asia in the Second Half of the 19th Century N. G. Mokrushinaa, *, R. N. Vakarchuka, and R. E. Tatevossiana a
Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, 123242 Russia *e-mail: [email protected]
Abstract—Materials on earthquakes in Samarkand and Ferhana regions (Republic of Uzbekistan) in 1868– 1892 are presented based on original sources of information not used before. The epicenter location and magnitude for the earthquakes April 7, 1869, and March 2, 1892, are evaluated for the first time; for the other two earthquakes (April 3, 1868, and September 18, 1892), the uncertainty of previously published solutions is significantly reduced. Reduction of uncertainties of prior solutions is achieved owing to the formalized method of epicentral and magnitude assessment, which works successfully with sparse datasets. One of the restrictions on the entire set of solutions is association of the epicenter with certain active tectonic structures. This criterion is used only for selecting the preferable solution from the entire set of solutions obtained solely from macroseismic data. The complete set of solutions is retained and can be used to analyze the accuracy and objectivity of the preferable solution. Keywords: historical earthquakes, macroseismology, macroseismic field equation DOI: 10.3103/S0747923920060055
INTRODUCTION The Central Asian region is one of the key places in the global seismotectonic picture (Fig. 1, inset). It is attributed to a zone of intracontinental seismicity, occupying a transitional position from active orogenic structures to stable platform regions. Although individual seismic stations were set up in the region at the very beginning of instrumental seismology (Tashkent station, e.g., began operating in 1901), high-quality instrumental observations began later, in 1955; therefore macroseismic data play an important role in studying regional seismicity. Figure 1 shows the epicenters of earthquakes with magnitudes of 6 or more from various catalogs in the studied region. It can be seen that only a small number of strong earthquakes occurred over the past 65 years. Formally, the seismic history of the region has been known since ancient times. In the catalog by N.V. Kondorskaya and N.V. Shebalin (Novyi…, 1977) (hereinafter referred to as the New Catalog), the first earthquake in the section “Central Asia and Kazakhstan” for which the source parameters were determined dates back to 250 BC. Later, after a long break, the parameters of several historical earthquakes of the 10th–18th centuries are given, based mainly on Arabic sources available from (Semenov, 1958). However, more or less regular seismicity information has been known only since 1865, when the Central Asian countries became part of the Russian Empire. Local newspapers were published in Russian (the first issue of
Turkestanskie Vedomosti was published on April 28, 1870). Reports from the region were included in newspapers published in Moscow and St. Petersburg. Travel diar
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