EXH1136043079

FROM: Michael Bailey, P.E.,Allen Jones, P.E.,and Doug Lindquist, Hart Crowser inc. RE: Sea-Tac Airport Third Runway c_,cago Probabilistic Seismic Hazard Analysis Results J-4978-I 4 D_rivt,. *¸ This memorandum presents geotechnical engineering findings from our probabilistic seismic hazard analysis (PSHA) for the Third Runway project at the Sea-Tac Airport. We present a relation between peak horizontal acceleration (PHA) and the return interval. With this seismic hazard curve, the Port of Seattle can select what level of earthquake, in terms of FairDal_.s mean annual return interval, and find the corresponding peak horizontal acceleration to design for. Analyses and Results Jer_,ev City The PSHA analysis involves evaluating the seismic hazard from sources in the region that wilt contribute to strong ground motions at the site. Strong ground motions are motions that have the potential to produce damage to the Third Runway project and are defined as motions with a PHA greater than about 0.05 g. Sources producing these types of Juneau earthquakes include Cascadia events in and between the North American Plate and the Juan de Fuca Plate, the Seattle Fault, and shallow crustal zones throughout Western Washington. The two most significant recent events in the Puget Sound region are the 1949 Olympia earthquake (PHA = 0.28 g) and the 1965 Seatac earthquake (PHA = 0.20 g). Lot, 9 Beach For this study, seismic hazard is a function of the variation in source magnitude, variation in earthquake return interval, and variation of source to site distance. Total seismic hazard for the Third Runway…

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PSCAA Advisory Council Meeting Agenda
Add to CalendarMWednesday Mar 11, 9:00am - 11:35am
1904 3rd Avenue, Suite 105, Seattle, WA 98101
Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]