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Two earthquakes hit Crockett, Calif. on Saturday afternoon.
Two earthquakes hit Crockett, Calif. on Saturday afternoon.
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Earthquake magnitudes measure the energy released by a tremor, but are not meant to calculate how intense the shaking is for those near the epicenter. To measure how forceful a quake felt to someone or something near the epicenter, geologists use something called the Modified Mercalli Intensity Scale. The following slides explain what it means when you see a roman numeral representing intensity on USGS readings and color-coded intensity maps. Information taken from a USGS magnitude vs. intensity comparison. less
Earthquake magnitudes measure the energy released by a tremor, but are not meant to calculate how intense the shaking is for those near the epicenter. To measure how forceful a quake felt to someone or ... more
Photo: Vincent Maggiora/The Chronicle
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Below a 3.0 magnitude: Earthquakes at this level are generally deemed level I in intensity. These are "Not felt except by a very few under especially favorable conditions," according to the USGS.
Below a 3.0 magnitude: Earthquakes at this level are generally deemed level I in intensity. These are "Not felt except by a very few under especially favorable conditions," according to the USGS.
Photo: USGS
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Magnitude 3.0 to 3.9 - Earthquakes at this level are typically level II, which. according to the USGS are "only felt by a few persons at rest, especially on upper floors of buildings," or level III, which carry "vibrations similar to the passing of a truck."
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Magnitude 3.0 to 3.9 -
Earthquakes at this level are typically level II, which. according to the USGS are "only felt by a few persons at rest, especially on upper floors of buildings," or level III, which
... more
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Magnitude 4 to 4.9 - quakes at this intensity are often level IV, which are widely felt but rarely cause serious damage or even level V, which are felt by nearly everyone and have the power to wake people up.
Magnitude 4 to 4.9 -
quakes at this intensity are often level IV, which are widely felt but rarely cause serious damage or even level V, which are felt by nearly everyone and have the power to wake people up.
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Magnitude 5 to 5.9 -The USGS says level VI intensity is where people start getting scared. By level VII we start seeing "considerable damage in poorly built or badly designed structures."
Magnitude 5 to 5.9 -
The USGS says level VI intensity is where people start getting scared. By level VII we start seeing "considerable damage in poorly built or badly designed structures."
Photo: Robert Gauthier/LA Times
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Magnitude 6.0 to 6.9 - As the 2014 Napa quake proved, A level VIII quake can take down "chimneys, factory stacks, columns, monuments" and walls.
By level IX many structures are knocked off of the foundation, and even well designed buildings can be thrown out of plumb. The 1989 Loma Prieta quake fell into this category.
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Magnitude 6.0 to 6.9 -
As the 2014 Napa quake proved, A level VIII quake can take down "chimneys, factory stacks, columns, monuments" and walls.
By level IX many structures are knocked off of the foundation, and
... more
Photo: Scott Strazzante, The Chronicle
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Quakes above magnitude 7.0 can range from
level VIII up. The three highest
levels X - where masonry homes are largely destroyed,
level XI - where bridges may come down, and
level XII where "damage is total" are the most intense. San Francisco's 1906 earthquake (damage pictured above) was considered a level XI quake.
lessQuakes above magnitude 7.0 can range from
level VIII up. The three highest
levels X - where masonry homes are largely destroyed,
level XI - where bridges may come down, and
level XII where "damage is total" are
... more
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Two earthquakes hit Crockett, Calif. on Saturday afternoon.
Two earthquakes hit Crockett, Calif. on Saturday afternoon.
Magnitude 3.7 earthquake strikes near Crockett, followed by aftershock
The United States Geological Survey reports a preliminary magnitude 3.7 earthquake struck near Crockett, Calif. on Saturday, followed by an aftershock that shook the same area less than 10 minutes later.
The first quake hit at 11:56 AM local time at a depth of 10 kilometers.
The second, smaller quake was reported at a preliminary magnitude of 2.7, and hit at 12:01 PM.
There was no initial word on damage or injury resulting from either quake. More information on this earthquake is available on the USGS event page.
See the latest USGS quake alerts, report feeling earthquake activity and tour interactive fault maps in the earthquake section.
