PALEOEARTHQUAKES IN THE PRIBAIKALIE: METHODS AND RESULTS OF DATING

Geodinamika i Tektonofizika

Anatoly V. Chipizubov¹  V. S. Imayev¹  Oleg P. Smekalin¹ 

[1] Institute of the Earth’s Crust;

关键词: paleoseismology;    paleoseismicity;    paleoearthquake;    morphometry;    trenching;   

DOI  :  10.5800/GT-2010-1-1-0006

来源: DOAJ

【 摘 要 】

In the Pribaikalie and adjacent territories, seismogeological studies have been underway for almost a half of the century and resulted in discovery of more than 70 dislocations of seismic or presumably seismic origin. With commencement of paleoseismic studies, dating of paleo-earthquakes was focused on as an indicator useful for long-term prediction of strong earthquakes. V.P. Solonenko [Solonenko, 1977] distinguished five methods for dating paleoseismogenic deformations, i.e. geological, engineering geological, historico-archeological, dendrochronological and radiocarbon methods. However, ages of the majority of seismic deformations, which were subject to studies at the initial stage of development of seismogeology in Siberia, were defined by methods of relative or correlation age determination.Since the 1980s, studies of seismogenic deformation in the Pribaikalie have been widely conducted with trenching. Mass sampling, followed with radiocarbon analyses and definition of absolute ages of paleo-earthquakes, provided new data on seismic regimes of the territory and rates of and recent displacements along active faults, and enhanced validity of methods of relative dating, in particular morphometry. Capacities of the morphometry method has significantly increased with introduction of laser techniques in surveys and digital processing of 3D relief models.Comprehensive seismogeological studies conducted in the Pribaikalie revealed 43 paleo-events within 16 seismogenic structures. Absolute ages of 18 paleo-events were defined by the radiocarbon age determination method. Judging by their ages, a number of dislocations were related with historical earthquakes which occurred in the 18th and 19th centuries, yet any reliable data on epicenters of such events are not available. The absolute and relative dating methods allowed us to identify sections in some paleoseismogenic structures by differences in ages of activation and thus provided new data for more accurate definitions of epicenters and magnitudes of the paleo-earthquakes. In some cases, it was revealed that neighboring dislocations of seismogenic structures, which were previously considered independent, had been subject to simultaneous opening.The article presents a new approach to selecting regression equations to estimate paleo-magnitudes with regard to specific geodynamic conditions as well as to levels of available knowledge on seismodislocations and reliability of available data parameters.

【 授权许可】

Unknown