Ground Motion Modeling in the Near-Source Regime: A Barrier Model

During the IMAGES Ⅲ-IPHIS-Leg Ⅱ Cruise in June 1997,a long pistoncore,MD972143(15°52.262'N,124°38.96'E,water depth 2989m),wasraised from Benham Rise,east of Luzon in the western Philippine Sea.Thecore measures 38m in length,consisting mainly of calcareous ooze.Intercalatedconspicuously in this thick sequence of calcareous ooze are 21 volcaniclayers.Four major age-diagnostic nannofossil datum levels were recognized:the first appearance datum(FAD)of Emiliania huxleyi(0.27Ma)at 365cm,the last appearance datum(LAD)of Pseudoemiliania lacunosa(0.46Ma)at 1105cm,the LAD of Calcidiscus macintyrei(1.59Ma)at 2510cm and the LAD of Discoaster broweri(1.95Ma)at 2970cm.A turbiditelayer at 33 to 34m,consisting mainly of foraminiferal sands,appears totruncate the sequence and result in a hiatus.The age of the lowermost partof the core(34-38m)was constrained as being older than 2.59Ma(the lastappearance of D.surculus)and younger than 2.78Ma(the last appearanceof D.tamalis).Based upon our preliminary nannofossil biochronology,thesetephra layers were deposited at 2.65Ma(?),2.1Ma,1.9Ma,1.7-1.8Ma,1.5Ma,1.35Ma,0.9Ma,0.8Ma and 0.5-0.3Ma,respectively.

並列關鍵字

Ground Motion ； Seismic Hazard:Near-Source ； Barrier

國際替代計量

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