Expected tsunami amplitudes and currents along the North American coast for Cascadia subduction zone earthquakes |
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| Authors: | Paul M Whitmore |
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| Institution: | (1) Alaska Tsunami Warning Center, 910 S. Felton St., 99645 Palmer, Alaska, U.S.A. |
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| Abstract: | Tsunamis are numerically modeled using the nonlinear shallow-water equations for three hypothetical Cascadia subduction zone earthquakes. Maximum zero-to-peak tsunami amplitudes and currents are tabulated for 131 sites along the North American coast. Earthquake source parameters are chosen to satisfy known subduction zone configuration and thermal constraints. These source parameters are used as input to compute vertical sea-floor displacement. The three earthquakes modeled are moment magnitude 8.8, 8.5, and 7.8. Maximum zero-to-peak tsunami amplitude for theMw = 8.8 earthquake is near 6 m normal to the fault break and maximum current is near 3.5 m/s. Maximum amplitudes decrease by about one-half north and south of the fault break in the source region. Tsunami amplitudes vary along the Alaskan coast from less than 0.5 to 1.6 m. The modeled amplitudes for theMw = 8.8 quake decrease to less than 0.4 m south of Point Conception, CA. TheMw = 7.8 earthquake generates a tsunami with a maximum amplitude of less than 1 m normal to the source. North and south of the fault break the maximum amplitude again decreases by about one-half. In all the models, amplitudes and currents arc less than one-sixth of the outer coast value within Puget Sound. |
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| Keywords: | Cascadia tsunami danger shallow water equations Puget Sound Cascadia subduction zone numerical modeling tsunami source tsunami models |
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