|Mitigation - Disaster Mitigation Guidelines for Hospitals and other Health Care Facilities in the Caribbean (PAHO)|
I. Not felt. Marginal and long period effects of large earthquakes.
II. Felt by persons at rest, on upper floors, or favorably placed.
III. Felt Indoors. Hanging objects swing. Vibration like passing of light trucks. Duration estimated. May not be recognized as an earthquake.
IV. Hanging objects swing. Vibration like passing of heavy trucks
or sensation of a jolt like a heavy ball striking the walls. Standing cars rock.
In the upper range of IV, wooden walls and frames creak.
V. Felt outdoors. Sleepers wakened. Liquids disturbed, some spilled. Small unstable objects displaced or upset. Doors swing, close, open. Shutters, pictures move. Pendulum clocks stop, start, change rate.
VI. Felt by all. Many frightened and run outdoors. Persons walk unsteadily. Windows, dishes, glassware broken. Knickknacks, books, etc., off shelves. Pictures off walls. Furniture overturned. Weak plaster, Masonry D1 cracked. Small bells ring (church and school). Trees, bushes shaken visibly or heard to rustle.
1 Masonry definitions from C.F. Richter's 1958 book, Elementary Seismology (W.H. Freeman and Company, San Francisco, California), are as follows: Masonry A--good workmanship, mortar, and design; reinforced, especially laterally; bound together by using steel, concrete, etc.; designed to resist lateral forces. Masonry B-good workmanship and mortar; reinforced but not designed in detail to resist lateral forces. Masonry Cordinary workmanship and mortar; no extreme weaknesses like failing to tie in at corners but not reinforced or designed against horizontal forces. Masonry D--weak materials such as adobe, poor mortar, low standards or workmanship; weak horizontally.
VII. Difficult to stand. Noticed by drivers. Hanging objects quiver. Furniture broken. Damage to Masonry D, including cracks. Weak chimneys broken at roof line. Fall of plaster, loose bricks, stones, tiles, cornices also unbraced parapets and architectural ornaments. Some cracks in Masonry C. Waves on ponds, water turbid with mud. Small slides and caving in along sand or gravel banks. Large bells ring. Concrete irrigation ditches damaged.
VIII. Steering of cars affected. Damage to Masonry C: partial collapse. Some damage to Masonry B; none to Masonry A. Fall of stucco and some masonry walls. Twisting, fall of chimneys, factory stacks, monuments, towers, elevated tanks. Frame houses moved on foundations if not bolted down; loose panel walls thrown out. Decayed piling broken off. Branches broken from trees. Changes in flow or temperature of springs and wells. Cracks in wet ground and on steep slopes.
IX. General panic. Masonry D destroyed; Masonry C heavily damaged, sometimes with complete collapse; Masonry B seriously damaged. General damage to foundations. Frame structures, if not bolted down, shifted off foundations. Frames racked. Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in the ground. In alluviated areas, sand and mud ejected, earthquake fountains and sand craters.
X. Most masonry and frame structures destroyed with their
foundations. Some well-built wooden structures and bridges destroyed. Serious
damage to dams, dikes, embankments. Large landslides. Water thrown on banks of
canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and
Rails bent slightly.
XI. Rails bent greatly. Underground pipelines completely out of service.
XII. Damage nearly total. Large rock masses displaced. Lines of sight and level distorted. Objects thrown in the air.