Modified Mercalli Intensity (MMI) Scale

Washington is earthquake country.

We know that earthquakes have occurred here in the past, and will occur again, but what can you expect when the ground shakes? We can anticipate what magnitude an earthquake will have, but the shaking intensity, or strength you experience from that earthquake varies widely based on factors like how far away from the earthquake you are, what type of soil or rock is beneath you, what type of building you are in, and more. Knowing what to expect is an important part of knowing how to get prepared for earthquake hazards in Washington!

Shaking intensity is described by the Modified Mercalli Intensity Scale To help you understand what the strongest levels of earthquake shaking might look like in different areas of Washington, use the tool below to select one or more Shaking Intensity levels, and see which cities/locations in Washington will experience that level of shaking in an earthquake. Click a city to display more information including images, videos, and links to information about which earthquake scenarios would cause that level of shaking.

Intensity Shaking Description
I Not felt
Not felt except by a very few under especially favorable conditions.
II Weak
Felt only by a few persons at rest, especially on upper floors of the building.
III Weak
Felt quite noticeably by persons indoors, especially on the 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 Light
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 Moderate
Felt by nearly everyone: many awakened, Some dishes, windows broken, Unstable objects overturned. Pendulum clocks may stop.
VI Strong
Felt by all, many frightened. Some heavy furniture moved; a few instance of fallen plaster. Damage slight.
VII Very strong
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.
VIII Severe
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 Violent
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 Extreme
Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.

Washington State

Clallam Jefferson GraysHarbor Mason Thurston Pacific Lewis Wahkiakum Cowlitz Clark Skamania Yakima Klickitat Whatcom Skagit Snohomish King Pierce Okanogan Chelan Kittitas Douglas Grant Benton Ferry Lincoln Adams Franklin Walla Walla Stevens PendOreille Spokane Whitman Garfield Columbia Asotin San Juan Island Kitsap
No Summary. Please tick one or more of the intensity above to show details.
back to top