Laserfiche WebLink
Chapter 9:Hazard Analysis—Tsunamis <br /> Figure 9-6).45 These inundation zones have been incorporated into the FIRM maps (V and <br /> VE zones) and guide land use and construction standards. The tsunami evacuation zones are <br /> derived from tsunami inundation maps, but are more conservative than the inundation snaps <br /> in that they encompass a broader area that are potentially at risk that should be evacuated and <br /> refer to readily identifiable physical landmarks such as roads where possible(see Figure 9-8). <br /> On the one hand,these evacuation zones should not be so broad as to jam evacuation capabil- <br /> ities; on the other hand,they should not be too narrow to risk injury or death. <br /> NOTE R MAY BE GREATER OR LESS THAN h , DO NOT CONFUSE. <br /> PRESENT WATER LEVEL/LINE MAY BE USED IN LIEU OF MSL, IF STATED. <br /> MAX <br /> MAX WATER LEVEL INTRUSION <br /> — <br /> -- ---—_ POINT <br /> h=HEIGHT OF T <br /> MEAN WAVE AT SHORELINE <br /> SEA LEVEL I R=RUNUP HEIGHT <br /> ABOVE MSL <br /> MSL 1 <br /> INUNDATION LIMIT <br /> Figure 9-6. Definition Sketch of Tsunami Inundation Terms <br /> The evacuation zone map applies to distant tsunamis, assuming worst case wave action from <br /> any probable source area. For local tsunamis, the arrival times are very short (typically min- <br /> utes), and the felt earthquake is likely to be the only warning that many residents will receive <br /> in advance of the first tsunami wave. Mitigation,therefore, depends primarily on public edu- <br /> cation for a swift and appropriate response from within the coastal communities. A new sys- <br /> tem is in place to alert police of a local tsunami generated from the southern coast of the <br /> island. This system senses sea level rise at six locations on this southern shoreline.46 It alerts <br /> the Pacific Tsunami Warning Center which immediately confirms the event by correlating it <br /> to an earthquake signal and advises the County Civil Defense (or the police after working <br /> hours). This system supplements the slower and less definitive earthquake-only local system <br /> currently in service. <br /> 45 Historical data on tsunamis is primarily scattered run-up values. Hilo is unique in having well-documented <br /> historical inundation lines for several tsunamis. Inundation for areas other than Hilo is the calculated"maxi- <br /> mum expectable inundation". <br /> 46 Walker,Daniel,"Local Tsunami Real-time Warning System,"Science of Tsunami Hazards,v.20,n. 1, <br /> 2002. <br /> 9-7 Hawaii County Multi-Hazard Mitigation Plan <br />