Lecture7_2011.knr

Steven ward 138 meter wave lituya bay 1720 run up

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Unformatted text preview: E age on West Tahoe Fault, 4.1-4.5 ka; Incline Village Fault, 0.6 ka; Stateline/North Tahoe Fault, Holocene. Size of MRE rupture: West Tahoe Fault, ~3.7-4.1 m; Incline Village, ~3-3.5 m; Stateline/North Tahoe, unknown. Total extension across basin is ~0.5 mm/yr. sedimentation rate extrapolation suggest ~60 ka age of slide, maybe younger. ~2000-3000 year potential recurrence interval for tsunami-generating M7 earthquake. West Tahoe Fault: ~55 km length has a potential of a M7.3 rupture. Figure 19. Comparison of the West Tahoe fault and the GF; both faults exhibit similar range front morphology, strike, and length. Together, these faults appear to be accommodating most of the extension (2–3 mm=yr) occurring within the northern Walker Lane at the latitude of Lake Tahoe. second method, the offset fan surface offshore Sugar Pine Point (Figs. 16 and 18) is presumed to be inactive since the Tioga glacial retreat (Dingler, 2007). The 10.5 m offset (Fig. 18) since 13 k.y. B.P. also produces a maximum vertical slip rate of ∼0:8 mm=yr. Overall, these data give rise to a vertical displacement rate between 0.4 and 0:8 mm=yr since the end of Tioga glaciation, which is slightly higher than the 0:5 mm=yr minimum slip-rate estimate (over the last ∼20 ka) reported by Kent et al. (2005). An extension rate can be estimated from vertical slip rate assuming simple fault geometry. For a 60° dipping normal fault, the vertical deformation rate is transformed into an extension rate between 0.3 and 0:5 mm=yr. The slip rate along the WTDPF may be higher than estimated because the MRE occurred at 4.1– 4.5 k.y. B.P. and, presumably, additional strain has accumulated during the quiescent interval. With a slip rate between 0.4 and 0:8 mm=yr, it is possible that ∼3 m of elastic strain has accumulated across the WTDPF. Coseismic slip of 3 m on the WTDPF could generate an M ≥ 7 event. The GF (Fig. 19) has a vertical deformation rate of 2–3 mm=yr over the last 2 k.y. (Ramelli et al., 1999), which can be converted to a 1:2–1:7 mm=yr extension rate (also assuming 60° dip). The combined extension rates of the GF and the WTDPF are consistent with the 2–3 mm=yr GPS derived extension rates across the Sierra Nevada frontal fault zone (Hammond and Thatcher, 2004, 2007). Earthquake triggering associated with normal fault earthquakes and resulting static stress changes have been used to explain normal fault event sequences (Nostro et al., 1997); therefore, it is important to compare paleoearthquake records between neighboring faults. Events on the IVF and GF at ∼500 yr B.P. (Ramelli et al., 1999; Dingler, 2007) suggest a possible relationship in the rupture timing, but the age uncertainty is large and coincident timing could also be re- Persistent Drought—60% of “normal”, Medieval Period Rooted Trees 110’ Submersible Cedar Grove Cry...
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