Here are some more charts to show some visual
differences between 8.7 and 9.+ earthquake magnitudes. (hope they format here ok)
Richter Magnitudes Earthquake Effects
Frequency of Occurence
Less than 2.0 Microearthquakes, not felt.
About 8,000 per day
2.0-2.9 Generally not felt, but recorded.
About 1,000 per day
3.0-3.9 Often felt, but rarely causes damage.
49,000 (estimated) per year
4.0-4.9 Noticeable shaking of indoor items, rattling noises. Significant damage unlikely.
6,200 (estimated) per
5.0-5.9 Can cause major damage to poorly constructed buildings over small regions. At most slight damage to
800 per year
6.0-6.9 Can be destructive in areas up to about 100 miles across in populated areas.
120 per year
7.0-7.9 Can cause serious damage over larger areas.
18 per year
8.0-8.9 Can cause serious damage in areas several hundred miles across.
1 per year
9.0 or greater Catastrophic Devastation.
1 per 20 years
Mercalli Intensity Scale
(I) - Not felt except by a very few under especially favourable conditions.
(II) - Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing.
(III) - Felt quite noticeably by persons indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing
motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.
(IV) - Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound.
Sensation like heavy truck striking building. Standing motor cars rocked noticeably.
(V) - Felt by nearly everyone; many awakened. Some dishes and windows broken. Unstable objects overturned. Pendulum clocks may stop.
(VI) - Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken... books off shelves... some heavy furniture
moved or overturned; a few instances of fallen plaster. Damage slight.
(VII) - Difficult to stand... furniture broken..damage negligible in building of good design and construction; slight to moderate in well-built
ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving motor cars.
(VIII) - Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly
built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved.
(IX) - General panic. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.
(X) - Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.
(XI) - Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly.
(XII) - Damage total. Lines of sight and level distorted. Objects thrown into the air.
Mercalli Intensity Scale
TABLE -- Modified Mercalli Intensity Scale
MMI Value / Summary Damage
/ Full Description
I. Not felt. Marginal and long period effects of large
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
IV. Hanging objects swing. Vibration like passing of heavy trucks;
or sensation of a jolt like a heavy ball striking the walls.
Standing motor cars rock. Windows, dishes, doors rattle.
Glasses clink. Crockery clashes. In the upper range of IV,
wooden walls and frame creak.
V. Pictures Move: Felt outdoors; direction estimated. 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. Objects Fall: Felt by all. Many frightened and run outdoors. Persons walk
unsteadily. Windows, dishes, glassware broken. Knickknacks,
books, etc., off shelves. Pictures off walls. Furniture moved
or overturned. Weak plaster and *masonry D cracked. Small bells
ring (church, school). Trees, bushes shaken (visibly, or heard
VII. Nonstruct Ural Damage: Difficult to stand. Noticed by drivers of motor cars. 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. Moderate Damage: Steering of motor 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 panels 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. Heavy Damage: 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,
shifted off foundations. Frames racked. Serious damage to
reservoirs. Underground pipes broken. Conspicuous cracks in
ground. In alluvial areas sand and mud ejected, earthquake
fountains, sand craters.
X. Extreme Damage: 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 flat
land. Rails bent slightly.
XI. Catastrophic Damage: Rails bent greatly. Underground pipelines completely out of
XII. Cataclysmic Devastation: Damage nearly total. Large rock masses displaced. Lines of
sight and level distorted. Objects thrown into the air.
Good workmanship, mortar, and design; reinforced, especially laterally, and bound together by using steel, concrete, etc.; designed
to resist lateral forces.
Good workmanship and mortar; reinforced, but not designed in detail to resist lateral forces.
Ordinary workmanship and mortar; no extreme weaknesses like failing to tie in at corners, but neither reinforced nor designed
against horizontal forces.
Weak materials, such as adobe; poor mortar; low standards of workmanship; weak horizontally.*
Modified Mercalli Intensity Scale
[edit on 28-3-2005 by Vajrayana]