OKLAHOMA
EARTHQUAKES
While there are hundreds of
earthquakes every year in Oklahoma,
they are rarely large enough on the
USGS Modified Mercalli Intensity Scale
to cause significant property damage.
Oklahoma has had only 2 earthquakes in the past 5 years above
5.0 magnitude, which is the typical threshold for causing property
damage according to USGS Modified Mercalli Intensity Scale.
TOP
4 EARTHQUAKES IN OKLAHOMA; PAST 5 YEARS
MAGNITUDE
1 Nov. 6, 2011 | 5.6 magnitude
2.1 miles SW of Wilzetta
6.0
5.0
1
5.6
4.0
2
5.1
3
4.8
4
3.2
2 Feb. 13, 2016 | 5.1 magnitude
19.3 miles NW of Fairview
3 Nov. 5, 2011 | 4.8 magnitude
1.6 miles W of Wilzetta
3.0
2.0
4 Nov. 8, 2011 | 3.2 magnitude
3.2 miles SW of Wilzetta
1.0
0
Source: USGS
continued on back
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HOW DO YOU MEASURE THE INTENSITY OF EARTHQUAKES?
The table on the right gives intensities that
are typically observed at locations near
the epicenter of earthquakes of different
magnitudes.
Abbreviated Modified Mercalli Intensity
Scale
I. Not felt except by a very few under especially
favorable conditions.
MAGNITUDE
TYPICAL MAXIMUM
MODIFIED MERCALLI
INTENSITY
1.0 —3.0
I
3.0—3.9
II —III
4.0—4.9 IV —V
5.0—5.9
VI —VII
6.0 — 6.9
VII — IX
7.0 and higher
VIII or higher
II. Felt only by a few persons at rest, especially on
upper floors of buildings.
III. Felt quite noticeably by persons indoors,
especially on upper floors of buildings. Many people
do not recognize it as an earthquake. Standing
motor cars may rock slightly. Vibrations 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, windows broken. Unstable objects overturned. Pendulum clocks may stop.
VI. Felt by all, many frightened. Some heavy
furniture moved; a few instances of fallen plaster.
Damage slight.
VIII. Damage slight in specially designed structures;
considerable damage in ordinary substantial buildings
with partial collapse. Damage great in poorly built
structures. Fall of chimneys, factory stacks, columns,
monuments, walls. Heavy furniture overturned.
IX. Damage considerable in specially designed
structures; well-designed frame structures thrown out
of plumb. 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 are
distorted. Objects thrown into the air.
VII. Damage negligible in buildings 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.
Source: United States Geological Survey’s (USGS) Earthquake
Hazards Program