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coxreNTs
<br />-space. A mathematical model bounded only by one plane aur-
<br />a; that is, the model is so large in other dimensions that only the
<br />t boundary affeN the results. Properties within the model are
<br />,umed to be homogeneous end usually isotropic.
<br />z A uni[ of frequency; cycles per second (cps).
<br />cane. The past 10,000 year of geologic time.
<br />roatatic pressure- The pressure in a liquid under static condi-
<br />m; the product of the unit weight of the liquid (water=l kg/Ll
<br />d the difference in elevation between the given point and the
<br />Fund water elevation.
<br />ocenter. The )oration in space where the slip responsible for an
<br />i}tquake occur; the focus of an earthquake.
<br />creels loop. (11 the stress-strain path of a material under cyc-
<br />loading conditions, or (2) a trace of the lag in the return o(en
<br />atically deformed specimen to iL original shape otter the load
<br />s been released.
<br />lent angle. The angle which a ny path makes with a perpen-
<br />~ular to an interface.
<br />to strength. The in-place strert~.h of a soil deposit.
<br />nsity. A numerical index describing the effects of an earth-
<br />eke on the earth's surface, on mom, and on structures built by
<br />n. The scale in common use in t`_e United States today is the
<br />dified Merralli scale of 1931 with intensity values indicated by
<br />man numerals from I to XII. The narrative descriptions of each
<br />:roily value are:
<br />Not felt or, except rarely under especially favorable circum-
<br />stances. Under certain conditons, at and outside the bound-
<br />ary of the area im which a great shock is felt: sometimes,
<br />birds, animals, reported uneasy or disturbed; sometimes
<br />dimness or nausea experienced; sometimes treEs, atruc•
<br />lures, liquids, bodies of water, may away; doom may awing,
<br />very slowly. -
<br />Felt indoor by few, especially on upper floors, or by sensitive,
<br />or nervous persons. Also, as in grade I, but often more
<br />noticeably: sometimes hangng objeMs may swing, espe-
<br />cially whew delicately auspemded; sometime trees, atrue-
<br />turea,liquids, badiea of water, may sway, doors may swing,
<br />very slowly, sometimes bird`, animals, reported uneasy ar
<br />disturbed; sometimes dizziness or nausea experienced.
<br />Felt indoors by several, motion usually rapid vibration. Some-
<br />times not recognized to be an earthquake et first. Duration
<br />estimated im some cases. Vibation like that due to passing
<br />of light, or lightly loaded trucks, or heavy trucks some dis•
<br />[ante away. Hanging objects may awing slightly.
<br />Movements maybe appreciable on upper levels of tall struc-
<br />tures. Rocked standing motor can slightly.
<br />Felt indoor by many, outdoor by few. Awakened few, espe-
<br />tielly light sleepers. Frightened no one, unless apprehen-
<br />sive from previous ezperiemce. Vibration like that due to
<br />passing of heavy or heavily loaded trucks. Sensation like
<br />henry body striking building or felling of henry objects in-
<br />side. Rattling of dishes, windows, doors; glassware and
<br />crockery clink and clash. Creaking of walls, frame, espe-
<br />tially in the upper range of this grade. Hanging objects
<br />swung, in numerous instarxrs. Disturbed liquids in open
<br />vessels slightly. Rocked standing motor can noticeably.
<br />. Felt indoors by practically all, outdoors by many or most; out-
<br />doors direction estimated. Awakened many, or most.
<br />Frightened few-slight excitement, a few ran outdoor.
<br />Buildings trembled throughout Broke dishes, glassware, to
<br />some extent Cracked windows-in some cases, but not gen-
<br />erally. Overtumedvases, small or unstable objeciv, in many
<br />instances, with~oceasional fall. Hanging objects, door,
<br />swing generally or considerably. Knocked pictures against
<br />wall, ar ewvng the i out of pGce. Opened, or closed, doors,
<br />!X
<br />shutter, abruptly. Pendulum clocks stopped, started ~ r ran
<br />fast, or slow. Moved small objects, furnishings, the later to
<br />slight extent. Spilled liquids in small amounts from well-
<br />filled open container. 'Rees, bushes, shaken slightly.
<br />VI. Felt by all, indoors and outdoor. Frightened many, excite-
<br />ment general, some alarm, many ran outdoor Awakened
<br />all. Persons made to move unsteadily. Trees, bushes, shaken
<br />slightly to moderately. Liquid set im strong motion. Smell
<br />bells rang-church, chapel, school, ate. Damage alight in
<br />poorly built buildings. Fall of plaster in small amount.
<br />Cracked plaster somewhat, especially fine cracks in chim•
<br />nays in same instances. Broke dishes, glassware, in consid-
<br />erable quantity, also some windows. Fall of knick-knacks,
<br />boles, pictures. Overturned furniture in many instances.
<br />Moved furnishings of moderately henry kind.
<br />VII. Frightened all: general alarm, all ran outdoor. Some, or
<br />many, found it dilFcult to stand. Noticed by persons driving
<br />motor cars. Trees end bushes shaken moderately to
<br />strongly. Waves on ponds, lakes, end running water. Water
<br />turbid from mud sorted up. Incaving to some extent of sand
<br />or gruel stream banks. Rang large church bells, etc. Sus•
<br />pended objects made to quiver. Damage negligible in build-
<br />ings o(gaad design and construction, slight to moderate in
<br />well-built ordinary buildings, considerable in poorly built or
<br />badly designed buildings, adobe houses, old wells (especially
<br />where laid up without mortar), spires, ate. Cracked chim•
<br />nays to considerable extent, walls to some extent. Fall of
<br />plaster in considerable W large amount, also some stucco.
<br />Broke numerous windows, furniture to some extent. Shook
<br />dowv loosened brickwork and tiles. Broke weak chimneys at
<br />the tmf-line (sometimes damaging roofs). Fall of wrnices
<br />from towers and high buildings. Dislodged bricks and
<br />stones. Overturned henry furniture, with damage from
<br />breaking. Damage considerable to concrete irrigation
<br />ditches.
<br />VIII. Fright general; alarm approaches panic. Disturbed persons
<br />drising motor cars. Trees shaken strongly-branches,
<br />trunks, broken off, especially palm trees. Ejected sand end
<br />mud in small amounts. Changes: temporary, permanent; in
<br />flow of springs end wells; dry wells renewed flow; in temper-
<br />ature of spring and well water. Damage sl fight in structures
<br />(brick) built especially to withstand earthquakes. Consider-
<br />able in ordinary substantial buildings, partial collapse:
<br />racked, tumbled down, wooden houses in some cases; threw
<br />out panel wells in frame structures, broke oR decayed pil-
<br />ing. Fall of walls. Cracked, broke, solid stone walla seri-
<br />ously. Wet ground to some extent, also ground on steep
<br />slopes. Twisting, fall, of chimneys, columns, monuments,
<br />also factory stacks, towers. Moved conspicuously, over-
<br />turned, very henry furniture.
<br />IX. Panic general. Cracked ground conspicuously. Damage con-
<br />siderable in (masonry) structures built especially to with-
<br />stand earthquakes: Threw out of plumb some wood-frame
<br />hou-=es built espaially to withstand earthquakes; greet in
<br />sub<tantial (masonry) buildings, some collapse in large,
<br />part; or wholly shifted frame buildings oR foundations,
<br />racked frames; serious to reservoir; underground pipes
<br />sometimes broken.
<br />X. Cracked ground, especially when loose and wet, up to widtJu
<br />of ses'erel inches; fissures up to a yard in width ren parallel
<br />to canal and stream banks. Landslides considerable from
<br />river banks and steep coasts. Shined sand and mud horiron-
<br />tally on beaches and flat lend. Changed level of water in
<br />wells. Threw water on banks of canals, lakes, riven, etc.
<br />Damage serious b dams, dikes, embankments Severe to
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