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<br />I Not felt by people, except under especially favorable circumstances. However, diZZiness or nausea may be experienced.
<br />Sometimes birds and animals are uneasy or disturbed. Trees, structures, liquids, bodies of water may sway gently, and doors may
<br />swing.very.slowly.
<br />II Felt indoors by a few people. especially on upper floors of multi.story buildings, and by sensitive or nervous persons.
<br />As in Grade I, birds and animals are disturbed, and trees, structures, liquids and bodies of water may sway. Hanging objects swing,
<br />especially if they are delicately suspended.
<br />III Felt indoors by several people, usually as a rapid vibration that may not be recognized as an earthquake at first. Vibration is similar
<br />to that of a light, or lightly loaded trucks, or heavy trucks some distance away. Duration may be estimated in some cases.
<br />Movements may be appreciable on upper levels of tall structures. Standing motor cars may rock slightly.
<br />
<br />IV Felt indoors by many, outdoors by a few. Awakens a few individuals, particularly light sleepers, but frightens no one except those
<br />apprehensive from previous experience. Vibration like that due to passing of heavy, or heavily loaded trucks. Sensation like a
<br />heavy body striking building, or the falling ot heavy objects inside.
<br />Dishes, windows and doors rattle; glassware and crockery clink and clash. Walls and house frames creak, especially if intensity is in the
<br />upper range of this grade. Hanging objects ohen swing. Liquids in open vessels are disturbed slightly. Stationary automobiles rock
<br />noticeably.
<br />
<br />V Felt indoors by practically everyone, outdoors by most people. Direction can often be estimated by those outdoors. Awakens
<br />many, or most sleepers. Frightens a few people, with slight excitement; some persons run outdoors. .
<br />Buildings tremble throughout. Dishes and glassware break to some extent. Windows crack in some cases, but not generally. Vases and
<br />small or unstable objects overturn in many instances, and a few fall. Hanging objects and doors swing generally or considerably.
<br />Pictures knock against walls, or swing out of place. Doors and shutters open or close abruptly. Pendulum clocks stop, or run fast or
<br />slow. Small objects move, and furnishings may shift to a slight eX1ent. Small amounts of liquids spill from well-filled open containers.
<br />Trees and bushes shake slightly. '
<br />
<br />VI Felt by everyone, indoors and outdoors. Awakens all sleepers. Frightens many people; general excitement, and some persons run
<br />outdoors.
<br />Persons move unsteadily. Trees and bushes shake slightly to moderately. Liquids are set in strong motion. Small bens in churches and
<br />schools ring. Poorly built buildings may be damaged. Plaster falls in small amounts. Other plaster cracks somewhat. Many dishes and
<br />glasses, and a few windows break. Knickknacks, books and pictures fall. Fumiture overturns In many instances. Heavy furnishings
<br />move.
<br />VII Frightens everyone. General alarm, and everyone runs outdoors.
<br />People find it difficult to stand. Persons driving cars notice shaking. Trees and bushes shake moderately to strongly. Waves form on
<br />ponds, lakes and streams. Water is muddied. Gravel or sand stream banks cave in. Large church bells ring. Suspended objects quiver.
<br />Damage is negligible in buildings of good design and construction; slight to moderate in well-buill ordinary buildings; considerable in
<br />poorly built or badly designed buildings, adobe houses, old walls (especially where laid up without mortar), spires, etc. Plaster and
<br />some stucco fall. Many windows and some furniture break. Loosened brickwork and tiles shake down. Weak chimneys break at the
<br />roofline. Cornices fall from towers and high buildings. Bricks and stones are dislodged. Heavy furniture overturns. Concrete irrigation
<br />ditches are considerably damaged.
<br />VIII General fright, and alarm approaches panic.
<br />Persons driving cars are disturbed. Trees shake strongly, and branches and trunks break off (especially palm trees). Sand and mud
<br />erupts in small amounts. Flow of springs and wells is temporarily and sometimes permanently changed. Dry wells renew flow.
<br />Temperatures of spring and well waters varies. Damage slight in brick structures-built especially to withstand earthquakes; considerable
<br />in ordinary substantial buildings, with some partial collapse; heavy in some wooden houses, with some tumbling down. Panel walls
<br />break away in frame structures. Decayed pilings break off. Walls fall. Solid stone walls crack and break seriously. Wet grounds and
<br />steep slopes crack to some eX1ent. Chimneys, columns, monuments and factory stacks and towers twist and fall. Very heavy furniture
<br />moves conspicuously or overturns.
<br />IX Panic is general.
<br />Ground cracks conspicuously. Damage is considerable in masonry structures built especially to withstand earthquakes; great in other
<br />masonry buildings - some collapse in large part. Some wood frame houses built especially to withstand earthquakes are thrown out of
<br />plumb, others are shifted wholly olf foundations. Reservoirs are seriously damaged and underground pipes sometimes break.
<br />X Panic is general.
<br />Ground. especially when loose and wet, cracks up to widths of several inches; fissures up to a yard in width run parallel to canal and
<br />stream banks. Landsliding is considerable !rom river banks and steep coasts~ Sand and mud shifts horizontally on beaches and flat
<br />land. Water level changes in wells. Water is thrown on banks of canals, lakes, rivers, etc. Dams, dikes. embankments are seriously
<br />damaged. Well.built wooden structures and bridges are severely damaged, and some collapse. Dangerous cracks develop in excellent
<br />brick walls. Most masonry and frame structures, and their foundations are destroyed. Railroad rails bend slightly. Pipe lines buried in
<br />earth tear apart or are crushed endwise. Open cracks and broad wavy folds open in cement pavements and asphalt road surfaces.
<br />Xl Panic is general.
<br />Disturbances in ground are many and widespread, varying with the ground material. Broad fissures, earth slumps, and land slips
<br />develop in sott, wet ground. Water charged with sand and mud is ejected in large amounts. Sea waves of significant magnitude may
<br />develop. Damage is severe to wood frame structures, especially near shock centers, great to dams, dikes and embankments, even at
<br />long distances. Few if any masonry structures remain standing. Supporting piers or pillars of large, well-built bridges are wrecked.
<br />Wooden bridges that "give" are less affected. Railroad rails bend greatly and some thrust endwise. Pipe lines buried in earth are put
<br />completely out of service.
<br />XU Panic is general.
<br />Damage is total, and practically all works of construction are damaged greatly or destroyed. Disturbances in the ground are great and
<br />varied, and numerous shearing cracks develop. Landslides, rock falls, and Slumps in river banks are numerous and extensive. Large
<br />rock masses are wrenched loose and torn off. Fault slips develop in firm rock, and horizontal and vertical offset displacements are
<br />notable. Water channels, both surface and underground, are disturbed and modified greatly. Lakes are dammed, new waterfalls are
<br />produced, rivers are deflected, etc. Surtace waves are seen on ground surfaces. Lines of sight and level are distorted. Objects are
<br />thrown upward into the air.
<br />
<br />3909 VINEYARD AVENUE
<br />Pleasanton, California
<br />
<br />MODIFIED MERCALLlINTENSITY SCALE
<br />
<br />TreacMell&RoIlo
<br />
<br />Date 06/08/051 Project No. 4186.01 I Figure 3
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