[S04-2] Historical and macroseismic studies of earthquakes II

[S04-2-04] Value of macroseismic information in earthquake studies in XX century: two case studies

^○Ruben Tatevossian, Nina Mokrushina (Institute of Physics of the Earth, Moscow, Russia)

It is generally accepted that the instrumental era in seismology had started from the beginning of XX century. In most international and national projects related to earthquake cataloging two time-periods are explicitly distinguished: historical and instrumental with time-boundary at 1900. It is commonly shared opinion that instrumental determinations of earthquake parameters are much more precise and reliable. Of course, seismologists are aware that the location accuracy and magnitude assessment can be rather poor in early-instrumental period, but some problems, specific for historical earthquakes, such as duplications, do not exist. In the presentation, on the base of Altai region catalogue for 1914, it is shown that this opinion is too optimistic. Another problem is location accuracy. It is shown that there is a gross error in hypocenter location of 1978 off-shore earthquake in the Black Sea. The error is evident from macroseimic data spatial distribution. It is a serious problem because the Mw=5.7 earthquake is the largest near the Russian coast of Black Sea.