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Abstract: Northern Vietnam has experienced large earthquakes in the past, but waveforms are not mentioned in the Vietnamese Specification for Bridge Design, and the acceleration response spectrum in these specifications has not been adequately studied under Vietnamese seismic conditions. The simulation of future earthquake events based on regional seismicity and a ground motion model is necessary because of the absence of data on strong ground motions. This paper summarizes artificial ground motion procedures, which were studied using a stochastic point-source model. Simulated waveforms were employed to synthesize seismograms with VN L1 and VN L2 ground motions estimated using a 475-year return period (M 5.8) and the largest recorded earthquake events (M 7.0). Ground motions were simulated using different source parameters and their response spectra were compared with corresponding available data. As a result, target response spectra are proposed for future earthquake-resistant design in Vietnam. [Copyright &y& Elsevier]

Abstract: New data on the age, composition, formation conditions, and ore-geochemical specialization of the Nui Chua layered peridotite-gabbro complex are reported. They evidence that the complex resulted from the Permo-Triassic mantle plume activity in northern Vietnam (southern framing of the Yangtze Platform). Two series of mafic and ultramafic rocks differing in ore productivity—layered (PGE-Cu-Ni) and pegmatoid (Fe-Ti-V)—have been recognized within the complex. The first estimates of the composition of their parental melts have been obtained. [Copyright &y& Elsevier]