Effect of Shallow Slip Amplification Uncertainty on Probabilistic Tsunami Hazard Analysis in Subduction Zones: Use of Long-Term Balanced Stochastic Slip Models
|Author(s)||Scala A.1, 2, Lorito S.2, Romano F.2, Murphy Shane3, Selva J.4, Basili R.2, Babeyko A.5, Herrero A.2, Hoechner A.5, Lovholt F.6, Maesano F. E.2, Perfetti P., Tiberti M. M.2, Tonini R.2, Volpe M.2, Davies G.7, Festa G.1, Power W.8, Piatanesi A.2, Cirella A.2|
|Affiliation(s)||1 : Univ Naples Federico II, Dept Phys Ettore Pancini, Naples, Italy.
2 : Ist Nazl Geofis & Vulcanol, Sez Roma 1, Rome, Italy.
3 : IFREMER, Plouzane, France.
4 : Ist Nazl Geofis & Vulcanol, Sez Bologna, Bologna, Italy.
5 : GFZ, Potsdam, Germany.
6 : NGI, Oslo, Norway.
7 : Geosci Australia, Canberra, ACT, Australia.
8 : GNS Sci, Lower Hutt, New Zealand.
|Source||Pure And Applied Geophysics (0033-4553) (Springer Basel Ag), 2020-03 , Vol. 177 , N. 3 , P. 1497-1520|
|WOS© Times Cited||9|
|Keyword(s)||Tsunamis, seismic-probabilistic tsunami hazard assessment, tsunami source models, stochastic seismic slip distributions|
The complexity of coseismic slip distributions influences the tsunami hazard posed by local and, to a certain extent, distant tsunami sources. Large slip concentrated in shallow patches was observed in recent tsunamigenic earthquakes, possibly due to dynamic amplification near the free surface, variable frictional conditions or other factors. We propose a method for incorporating enhanced shallow slip for subduction earthquakes while preventing systematic slip excess at shallow depths over one or more seismic cycles. The method uses the classic k(-2) stochastic slip distributions, augmented by shallow slip amplification. It is necessary for deep events with lower slip to occur more often than shallow ones with amplified slip to balance the long-term cumulative slip. We evaluate the impact of this approach on tsunami hazard in the central and eastern Mediterranean Sea adopting a realistic 3D geometry for three subduction zones, by using it to model similar to 150,000 earthquakes with M-w from 6.0 to 9.0. We combine earthquake rates, depth-dependent slip distributions, tsunami modeling, and epistemic uncertainty through an ensemble modeling technique. We found that the mean hazard curves obtained with our method show enhanced probabilities for larger inundation heights as compared to the curves derived from depth-independent slip distributions. Our approach is completely general and can be applied to any subduction zone in the world.