hazard identification and vulnerability analysis - Mason County

More documents

Recommendations

Info

EARTHQUAKES DEFINITION An earthquake is a shaking of the earth’s crust, which can be mild or violent depending on the intensity of the quake. Some areas of the United States are more susceptible to earthquakes than other areas. An earthquake can be felt in an area ranging from several hundred square miles to several thousand square miles. If damage occurs, it may be limited to dishes falling from shelves and breaking or it may topple major buildings, overpasses, bridges and other vital structures. The Richter Scale is used to measure the magnitude of an earthquake. The Modified Mercalli Intensity Scale is used to describe earthquake effects. RICHTER AND MODIFIED MERCALLI INTENSITY SCALES Richter Scale M=1 to 3: Recorded on local seismographs, but generally not felt. M=3 to 4: Often felt, no damage. M=5: Felt widely, slight damage near epicenter. M=6: Damage to poorly constructed building and other structures within ten kilometers. M=7: “Major” earthquake, causes serious damage up to one hundred kilometers. M=8: “Great” earthquake, great destruction, loss of life over several hundred kilometers M=9: Rare great earthquake, major damage over a large region over one thousand kilometers. Modified Mercalli Scale I. Not felt except by a very few under especially favorable circumstances. II. Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. III. Felt quite noticeably indoors, especially on upper floors of buildings, but many people don not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration like passing of truck. IV. During the day felt indoors by many, outdoors by few. At night some awakened. Dishes, windows, doors disturbed; walls made cracking sound. Sensations like heavy truck striking building. Standing motor cars rocked noticeably. V. Felt by nearly everyone; many awakened. Some dishes, windows, etc., broken; a few instances of cracked plaster; unstable objects overturned. Disturbance of trees, poles and other tall objects sometimes noticed. Pendulum clocks may stop. 7
HISTORY VI. Felt by all; many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster or damaged chimneys. Damage slight. VII. Everybody runs outdoors. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable in poorly build or badly designed structures; some chimneys broken. Noticed by persons driving motor cars. VIII. Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse; great in poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. Sand and mud ejected in small amounts. Changes in well water. Disturbed persons driving motor cars. IX. Damage considerable in specially designed structures; well designed frame structures thrown out of plumb; great in substantial buildings, with partial collapse. Building shifted off foundations. Ground cracked conspicuously. Underground pipes broken. X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations; ground badly cracked. Rails bent. Landslides considerable from river banks and steep slopes. Shifted sand and mud. Water splashed (slopped) over banks. XI. Few, if any masonry, structures remain standing. Bridges destroyed. Broad fissures in ground. Underground pipe lines completely out of service. Earth slumps and land slips in soft ground. Rails bent greatly. XII. DAMAGE TOTAL. Waves seen on ground surfaces. Lines of sight and level distorted. Objects thrown upward into the air. The Puget Sound region is entirely within Seismic Risk Zone 3, requiring that buildings be designed to withstand major earthquakes measuring 7.5 in magnitude. It is anticipated, however, that earthquakes caused from seductions plate stress can reach a magnitude greater than 8.0. The part of Washington State east of the Cascades has historically been subject to shallow, though infrequent, smaller earthquakes up to magnitude of 6.0..Washington State is vulnerable to the following earthquake risks: Date Washington State Significant Earthquakes Time (PST) Latitude/ Longitude Depth (Km) Mag Location December 12, 1880 2040 47 . 30' 122 . 30' 5.5 Puget Sound April 30, 1882 2248 47 . 00' 123 . 00' deep 6.0 Olympia area 8
Page 1 and 2: MASON COUNTY HAZARD IDENTIFICATION
Page 3 and 4: Seattle, 20 miles northwest of Olym
Page 5 and 6: Mason County, due to its location a
Page 7: Resources United States Geological
Page 11 and 12: America, the Juan de Fuca plate sli
Page 13 and 14: Puget Sound basin would directly af
Page 15 and 16: Subduction Zone Earthquakes: Althou
Page 17 and 18: Conclusions Mason County will exper
Page 19 and 20: FLOODING Definition: An inundation
Page 21 and 22: ATTACHMENT I SKOKOMISH RIVER BASIN
Page 23 and 24: ATTACHMENT III SATOP RIVER BASIN 22
Page 25 and 26: normal part of most forest and rang
Page 27 and 28: LAND SHIFT (SLIDES / EROSION) Defin
Page 29: HIGHWAY 101 MAJOR SLIDE AREAS (Sout
Page 38: SLIDE AREAS ALONG HIGHWAY 3 37
Page 43 and 44: HARSTEME ISLAND SLIDE AREAS 42
Page 45 and 46: SEVERE STORMS Definition Severe sto
Page 47 and 48: The most severe snowstorms that hav
Page 49 and 50: TSUNAMI, HIGH WAVES, SEICHES Defini
Page 51 and 52: VOLCANOS/ASH FALL Definition A volc
Page 53 and 54: • Magma or molten rock or lava or
Page 55 and 56: Conclusion volcano. Examples of suc
Page 57 and 58: its three 27,000 kilowatt generator
Page 59 and 60:
Major petroleum shortages developed
Page 61:
History Hazardous material incident
show all

hazard identification and vulnerability analysis - Mason County

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?