THE DAMAGE POTENTIAL OF INTRAPLATE EARTHQUAKES

Several noteworthy earthquakes have occurred in recent years that one can categorize as intraplate or within-plate earthquake. In ۱۹۸۵, vertical accelerations exceeding I g were recorded by strong motion instruments in near-source region of a large earthquake (moment magnitude ۶.۸) in the Nahanni River region of the western North America (Weichert et al., ۱۹۸۶). The Nahanni earthquake occurred in a tectonic regime characterized by high horizontal stresses and low observed seismicity rates, had a thrust mechanism, and produced do surface faulting despite a shallow focal depth of about ۱۰ km.Another set of records from a typical mid-plate event is the Gazli earthquake. On ۸ April ۱۹۷۶, an earthquake with a magnitude of Ms = ۷.۰. was located approximately ۳۰ km northwest of the town of Gazli. On ۱۷ May ۱۹۷۶, the second shock, with a magnitude of Ms = ۷.۰, occurred approximately ۲۰ km west of the first event. On ۱۹ March ۱۹۸۴, the third large M. = ۷.۰ earthquake occurred at a distance approximately ۲۰ km northwest of Gazli (Simpson and Leith, ۱۹۸۵; Eyidogan, Nabelek, and Nafim, ۱۹۸۵).The recent events were widely felt. In this paper, we examine the damage potential of these events, by comparing measured ground motion severity and inelastic response, to those of ۱۹۷۹ El-Centro, California Earthquake (ML=۶,۷). The El-Centro event was chosen as the reference for our comparison because it was one of the most damaging earthquake. The El-Centro ground motions may serve as a basis to measure the damage potential of future earthquakes, which may be similar to Nahanni and Gazli in terms of ground niotions.