Guam Hazard Mitigation Plan - Western States Seismic Policy Council

SECTIONFIVERisk AssessmentSimilar to earlier versions of the Guam HMP, and shown in Tables F-5 to F-7, in terms ofvillage-level population exposed to very high and high liquefaction hazard, Santa Rita leads with698 people (approximately 8.0 percent of the village population), followed by Tamuning (202people, 1.0 percent of the village population) and Hagatna (183 people, 15.6 percent of the villagepopulation).Exposure of the EFMUTS by number of facilities is concentrated in Hagatna village, with 14Essential Facilities that are worth $12.5 million, as shown in Tables F-5 to F-8 (Appendix F[Vulnerability and Potential Loss Results by Village]). Only 13 Major Utilities (seven in Piti) and19 Transportation Systems (six in Hagatna and five in Piti) are located in high and very highliquefaction areas.The village-level exposure of GBS is concentrated in three villages: Santa Rita with 213structures worth $16.8 million, Piti with 187 structures worth $26.7 million, and Hagatna with128 structures worth $44.5 million.Flooding: Coastal and RiverineThe 2007 Guam FIRM was used to determine the Special Flood Hazard Area (SFHA). As such,the population on Guam that is located in the 100-year floodplain consists of 7,440 people (4.12percent), as shown in Tables 5-20 and 5-21 and Table F-9 (Appendix F [Vulnerability andPotential Loss Results by Village]). A similarly small proportion of Guam’s GBS is exposed tothe floodplain with 2,182 buildings (5.5 percent), worth $397.9 million. A larger portion ofEFMUTS is exposed with 143 facilities (16.8 percent), worth $257.5 million.A large portion of the exposed EFMUTS facilities are located adjacent to Apra Harbor and are apart of the port facilities. As such, a total of 40 facilities (30.1 percent) in Transportation Systems,worth $76.9 million, are exposed to a flood. Though it is unlikely that a flood would completelydestroy some of the large facilities at the port, such as the cranes used to load and unload cargo,the potential exposure of these facilities to flood shows that a flood could affect the regularfunctions of these facilities. If a flood affects the functions at the port in Apra Harbor, themovement of goods on and off the island would be affected. A value for the normal and dailyfunctions of these facilities has not been assessed for this analysis, but disruption of thesefunctions would be a secondary potential effect of this hazard event.In terms of village-level population exposure, as shown in Tables F-9 and F-10 (Appendix F[Vulnerability and Potential Loss Results by Village]), Agat has the largest number of exposedpopulation with 1,283 people (19.4 percent of the village population). Tamuning hasapproximately 1,200 people residing in the SFHA. In addition, Santa Rita and Mongmong-Toto-Maite both have similar quantities of exposed populations, with 750 people (8.6 percent of thevillage population) and 790 people (11.6 percent of the village population), respectively.Exposure of the EFMUTS is concentrated in Hagatna with 35 facilities (mostly EssentialFacilities) worth $26.0 million. Piti and Tamuning follow with 21 exposed facilities each, worth$99.0 million in Piti and $73.8 million in Tamuning.Hagatna has 402 GBS structures (64.0 percent of the village GBS), worth $139.8 million, that areexposed to a flood hazard. Agat has 364 exposed structures (26.7 percent of the village GBS) witha value of $31.0 million. Merizo has 372 exposed structures (55.2 percent of the village GBS),and their value is $30.6 million.5-64