Guam Hazard Mitigation Plan - Western States Seismic Policy Council

SECTIONFIVERisk Assessmenthistorical records for most of these storms, these accidents were likely due to the high winds andimproper anchoring or mooring of the vessels prior to landfall of the storms.Probability of Future EventsThe FAA has many rules and regulations to minimize the potential for airline accidents to occur.After the Korean Air accident, the NTSB made many recommendations specific to the GIAA toimprove the safety for large commercial airplanes using this airport. The near-tragic accident ofthe Philippines Airlines Airbus in 2002 demonstrated that these types of accidents are repeatable.Also, this accident brought to light that the FAA and the GIAA had not acted on many of theNTSB recommendations that resulted from the Korean Air accident.No standard method has been developed to predict the probability of an airplane transportationaccident on Guam.5.3.15 Tropical CycloneNatureA tropical cyclone is a general term for an intense, circulating storm that covers all of thefollowing terms: tropical depression, tropical storm, typhoon, and super typhoon.Tropical cyclones occur over tropical and subtropical oceans. These storms are low-pressureweather systems that range in size from 120 to 1,500 miles across. In the northern hemisphere,the winds of a tropical cyclone blow counter-clockwise around a center of organized, deepthunderstorms, where the strongest winds generally reside. The various names or classificationsfor tropical cyclones relate to the intensities of the storms:• A tropical depression has maximum sustained winds of 38 mph. A tropical depression has aclosed circulation. The Joint Typhoon Warning Center generally issues warnings when thecirculation reaches 29 mph.• A tropical storm has maximum sustained winds in the range of 39 to 73 mph.• A typhoon has maximum sustained winds in the range of 74 mph or greater.• A super typhoon is a special class of typhoon that has maximum sustained winds of 150 mphor greater.The size and intensity of a tropical cyclone are not related. Small, very intense typhoons andlarge, relatively weak typhoons are possible. A large-diameter tropical cyclone may miss alandmass by a large distance and still result in heavy rains and high winds on the landmass, butthe center of the storm, which is where the storm is most intense, would have missed thelandmass. A small-diameter tropical cyclone of the same intensity needs to have a direct ornearly direct hit on a landmass to cause substantial damage. In this situation, the center of thesmall-diameter tropical cyclone would have hit or nearly hit the landmass, likely resulting inheavy damage.Tropical cyclones can occur at any time in the western North Pacific Ocean, and the route ortrack that a tropical cyclone follows can vary. These storms can intensify rapidly or remain at arelatively low intensity (i.e., remain a tropical depression) for their whole existence. To a certainextent, meteorologists can forecast the track that a tropical cyclone will likely take, the intensity5-47