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<br />,
<br />
<br />.
<br />
<br />/III.
<br />
<br />.
<br />'h<'.
<br />
<br />XI.
<br />XI I.
<br />
<br />._,
<br />
<br />Modified Mercalli Intensity Scale
<br />(from Richter, 195B)
<br />
<br />I.
<br />
<br />Not felt. Marginal and long-period effects of large earthquakes.
<br />felt by persons at rest, on upper floors, or favorably placed.
<br />felt indoors. Hanging Objects swing. Vibration like passing of light tructs.
<br />Duration estimated. May not be recognized as an earthquake.
<br />Hanging objects swing. Vibration like passing of heavy trucks; or sensation
<br />of a jolt like a heavy ball striking the walls. Standing motor cars rock I
<br />Windows, dishes, doors rattle, Glasses clink. Crockery clashes. In the ~pper:
<br />range of II' wooden wall s and frame creak.
<br />felt outdoors; direction estimated. Sleepers wa~ened. Liquids disturbed
<br />some spilled. Small unstable objects displaced or upset. Doors swing, close,
<br />open. Shutters, pictures move. Pendulum clocks stop, start, change rate.
<br />felt by all. Many frightened and run outdoors. Persons walk unsteadily.
<br />Windows, dishes, glassware broken. Knickknacks, books, etc., off shelves.
<br />Pictures off- walls. furniture moved or overturned. Weak plaster and masonry
<br />D* cracked. Small bells ring. Trees, bushes shaken visibly, or heard to
<br />rustle. '
<br />Difficult to stand. Noticed by drivers of motor cars. Hanging objects quiver
<br />Furniture broken. Damage to masonry D, including cracks. Weak chimneys broken
<br />at roof line. Fall of plaster, loose bricks.. stones, tiles, cornices,
<br />unbraced parapets, and architectural ornaments. Some cracks in masonry C.
<br />Waves on ponds; water turbid with mud. Small slides and caving in along sand
<br />or gravel banks. Large bells ring. Concrete irrigation ditches damaged.
<br />Steering of motor cars affected. Damage to masonry; partial collapse. Some
<br />damage,to masonry B; none to masonry A. Fall of stucco and some masonry walls,
<br />Twisting, fall of chimneys, factory stacks, monuments, towers, elevated tanks,
<br />Frame houses moved on foundations if not bolted down; loose panel walls thrown
<br />out. Decayed piling broken off. Branches broken from trees. Changes in flow'
<br />or temperature of springs and wells. Cracks in wet ground and on steep slopes,
<br />General panic. r.:asonry 0 destroyed; masonry C heavily damaged; sometimes with
<br />complete collapse; masonry B seriously damaged. General damage to foundations.
<br />Frame structures, if not bolted, shifted off foundations. frames racked.
<br />Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in
<br />'ground. In alluviated areas sand and mud ejected, earthquake fountains, sand
<br />craters.
<br />)'lost masonry and frame structures destroyed with their foundations. Some well-
<br />built wooden structures and bridges destroyed. Serious damage to da~s, dikes,
<br />embankments. Large landsl ide. \'!ater thrown on banks of canal', rivers, lakes,
<br />etc. Sand and mud shifted horizontally on beaches and flat land. ,Rails bent
<br />sl ightly.
<br />Rails bent greatly. Underground pipelines completely out of service.
<br />Damage nearly total. large rock masses displaced. Lines of light and level
<br />distorted. Objects thrOlin into the air.
<br />
<br />,
<br />
<br />-'.
<br />
<br />IV.
<br />
<br />V.
<br />
<br />VI.
<br />
<br />VII.
<br />
<br />X.
<br />
<br />* Note: Criteria for various grades of masonry construction described below.
<br />
<br />11asonry A. Good I-.'ol'kmanship, mortar, and design; reinforced, especially
<br />laterally, and bound together by using steel, concrete, etc.; designed
<br />to resist lateral forces.
<br />r':asonry B. Good ~Iorkmanship and mortar; reinforced" but not designed in
<br />detall-uJ resist lateral forces.
<br />":asonry C. Ordinary workrr,ansflip and mortar; no extr!'me ~..eaknesses like
<br />Tall1ng to tie in at' corners, but neither reinforced nor designed cgainst
<br />horizontal forces.
<br />I':asonry D. 1'1eak materials, such as adobe; poor mortar; low standards of
<br />"'or~manship; weak hori lontally.
<br />
<br />Extracted from:
<br />Earthquake Potential in Colorado
<br />by Kirkham and Rogers
<br />
<br />,
<br />
<br />-23
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