SHAKE, RATTLE AND ROLL:
STUDYING THE EFFECTS OF AN EARTHQUAKE
Kenneth L. Verosub
Department of Geology
University of California - Davis
Davis, CA 95616
Level: Grades 5 - 8
Anticipated Learning Outcomes
Prior knowledge about earthquakes is not necessary. The
activity is designed to take advantage of the interest in earthquakes that
is generated by a strong earthquake somewhere in the United States or even
elsewhere in the world. The activity could also be done with newspaper clippings
from an older, earlier earthquake.
Results and Discussion
Here are some newspaper accounts of what people experienced in a recent earthquake in southern California along with possible assignments of the Modified Mercalli intensity level.
Modified Mercalli Intensity Scale
Reprinted with permission from Earthquake Country by Robert
published by Sunset Books (1969).
|I||Not felt by people, except under specially favorable circumstances.
However, dizziness or nausea may be experienced.|
Sometimes birds and animals are uneasy or disturbed. Trees, structures, liquids, bodies of water may sway gently, and doors may swing very slowly.
|II||Felt indoors by a few people, especially on upper floors
of multistory buildings, and by sensitive or nervous persons.|
As in Grade I, birds and animals are disturbed, and trees, structures, liquids and bodies of water may sway. Hanging objects swing, especially if they are delicately suspended.
|III||Felt indoors by several people, usually as a rapid vibration
that may not be recognized as an earthquake at first. Vibration is similar
to that due to passing of a light, or lightly loaded trucks, or heavy trucks
some distance away. Duration may be estimated in some cases.|
Movements may be appreciable on upper levels of tall structures. Standing motor cars may rock slightly.
|IV||Felt indoors by many, outdoors by few. Awakens a few individuals,
particularly light sleepers, but frightens no one except those apprehensive
from previous experience. Vibration like that due to passing of heavy, or
heavily loaded trucks. Sensation like a heavy body striking building, or
the falling of heavy objects inside.|
Dishes, windows and doors rattle; glassware and crockery clink and clash. Walls and house frame creak especially if intensity is in the upper range of this grade. Hanging objects often swing. Liquids in open vessels are disturbed slightly. Stationary automobiles rock noticeably.
|V||Felt indoors by practically everyone, outdoors by most
people. Direction can often be estimated by those outdoors. Awakens many,
or most sleepers. Frightens a few people, with slight excitement; some persons
Buildings tremble throughout. Dishes and glassware break to some extent. Windows crack in some cases, but not generally. Vases and small or unstable objects overturn in many instances, and a few fall. Hanging objects and doors swing generally or considerably. Pictures knock against walls, or swing out of place. Doors and shutters open or close abruptly. Pendulum clocks stop, or run fast or slow. Small objects move, and furnishings may shift to a slight extent. Small amounts of liquids spill from well-filled open containers. Trees and bushes shake slightly.
|VI||Felt by everyone, indoors and outdoors. Awakens all sleepers.
Frightens many people; general excitement, and some persons run outdoors.|
Persons move unsteadily. Trees and bushes shake slightly to moderately. Liquids are set in strong motion. Small bells in churches and schools ring. Poorly built buildings may be damaged. Plaster falls in small amounts. Other plaster cracks somewhat. Many dishes and glasses, and a few windows, break. Knick-knacks, books and pictures fall. Furniture overturns in many instances. Heavy furnishings move.
|VII||Frightens everyone. General alarm, and everyone runs outdoors.|
People find it difficult to stand. Persons driving cars notice shaking. Trees and bushes shake moderately to strongly. Waves form on ponds, lakes and streams. Water is muddied. Gravel or sand stream banks cave in. Large church bells ring. Suspended objects quiver. Damage is negligible in buildings of good design and construction; slight to moderate in well-built ordinary buildings; considerable in poorly built or badly designed buildings, adobe houses, old walls (especially where laid up without mortar), spires, etc. Plaster and some stucco fall. Many windows and some furniture break. Loosened brickwork and tiles shake down. Weak chimneys break at the roofline. Cornices fall from towers and high buildings. Bricks and stones are dislodged. Heavy furniture overturns. Concrete irrigation ditches are considerably damaged.
|VIII||General fright, and alarm approaches panic|
Persons driving cars are disturbed. Trees shake strongly, and branches and trunks break off (especially palm trees). Sand and mud erupts in small amounts. Flow of springs and wells is temporarily and sometimes permanently changed. Dry wells renew flow. Temperature of spring and well waters varies. Damage slight in brick structures built especially to withstand earthquakes; considerable in ordinary substantial buildings, with some partial collapse; heavy in some wooden houses, with some tumbling down. Panel walls break away in frame structures. Decayed pilings break off. Walls fall. Solid stone walls crack and break seriously. Wet ground and steep slopes crack to some extent. Chimneys, columns, monuments and factory stacks and towers twist and fall. Very heavy furniture moves conspicuously or overturns.
|IX||Panic is general|
Ground cracks conspicuously. Damage is considerable in masonry structures built especially to withstand earthquakes; great in other masonry buildings--some collapse in large part. Some wood frame houses built especially to withstand earthquakes are thrown out of plumb, others are shifted wholly off foundations. Reservoirs are seriously damaged, and underground pipes sometimes break.
|X||Panic is general|
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 stream banks. Landsliding is considerable from river banks and steep coasts. Sand and mud shifts horizontally on beaches and flat land. Water level changes in wells. Water is thrown on banks of canals, lakes, rivers, etc. Dams, dikes, embankments are seriously damaged. Well-built wooden structures and bridges are severely damaged, and some collapse. Dangerous cracks develop in excellent brick walls. Most masonry and frame structures, and their foundations, are destroyed. Railroad rails bend slightly. Pipe lines buried in earth tear apart or are crushed endwise. Open cracks and broad wavy folds open in cement pavements and asphalt road surfaces.
|XI||Panic is general|
Disturbances in ground are many and widespread, varying with the ground material. Broad fissures, earth slumps, and land slips develop in soft, wet ground. Water charged with sand and mud is ejected in large amounts. Sea waves of significant magnitude may develop. Damage is severe to wood frame structures, especially near shock centers; great to dams, dikes and embarkments, even at long distances. Few if any masonry structures remain standing. Supporting piers or pillars of large, well-built bridges are wrecked. Wooden bridges that "give" are less affected. Railroad rails bend greatly, and some thrust endwise. Pipe lines buried in earth are put completely out of service.
|XII||Panic is general|
Damage is total, and practically all works of construction are damaged greatly or destroyed. Disturbances in the ground are great and varied, and numerous shearing cracks develop. Landslides, rock falls, and slumps in river banks are numerous and extensive. Large rock masses are wrenched loose and torn off. Fault slips develop in firm rock, and horizontal and vertical offset displacements are notable. Water channels, both surface and underground, are disturbed and modified greatly. Lakes are dammed, new waterfalls are produced, rivers are deflected, etc. Surface waves are seen on ground surfaces. Lines of sight and level are distorted. Objects are thrown upward into the air.