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Tsunami 15.4.2 Property Property Impacted The impact of tsunami waves and the scouring associated with debris that may be carried in the water could be damaging to all structures along beaches, low-lying coastal areas, tidal flats, and river deltas. The most vulnerable are those in the front line of tsunami impact and those that are structurally unsound. The Hazus analysis indicated that 73 percent of the exposed structures (2,978 structures) would be impacted by the modeled scenario event. Damage Estimates Table 15-4 summarizes Hazus estimates of tsunami damage in the planning area. The estimated damage value is associated with the tsunami wave only; it does not include additional damage that may occur as a result of debris battering structures as the tsunami wave rushes in and out of the inundation area or fires caused by an earthquake and tsunami event. The debris estimate includes only structural debris and building finishes; it does not include additional debris that may result from a tsunami event, such as from boats, trees, sediment, building contents, bridges, or utility lines. Table 15-4. Estimated Impact of a Tsunami Event in the Planning Area Structure Debris (tons) 31 Buildings Impacteda 2,978 Structure Value Damaged $785,192,914 Content Value Damaged $803,298,822 Total Value Damaged $1,588,491,736 Damage as % of Total Value 0.8% a. “Impacted” assumes floodwater over lowest finished floor Structures that were built to current floodplain regulations in the tsunami inundation area may have some level of protection, particularly if they were built to withstand wave action. In the unincorporated County, an estimated 79 percent of the housing units were built before the County entered the National Flood Insurance Program and began enforcing floodplain regulations. It is unknown how many of these structures are located in tsunami inundation areas. In addition to structure damage, ships moored at piers and in harbors often are swamped and sunk or are left battered and stranded high on the shore. 15.4.3 Critical Facilities Damage Estimates Figure 15-7 shows the estimated damage to critical facilities from a tsunami event. The average amount of damage to structures, measured as a percentage of total value, ranges from 5 to 36 percent of total value and average damage to contents ranges from 15 to 100 percent, depending on critical facility category. 15-11