Magnitude 5.1 quake strikes Los Angeles: macroseismic analysis

A magnitude-5.1 earthquake centered near Los Angeles caused no major damage but jittered nerves throughout the region as dozens of aftershocks followed. The U.S. Geological Survey said the quake struck at about 9:09 p.m. Friday and was centered near Brea in Orange County _ about 20 miles (32 kilometers) southeast of downtown Los Angeles _ at a depth of about 5 miles (8 kilometers). It was felt as far south as San Diego and as far north as Ventura County, according to the USGS. Broken glass, gas leaks, water main breaks and a rockslide were reported near the epicenter, according to Twitter updates from local authorities.

Macroseismic analysis

Date 29/03/2014      UTC 04:09:42
Latitude 33.92° N      Longitude 117.94° W
Magnitude 5.1           Depth 7.5 Km
The following analysis shows the macroseismical effects based on a model hereby displayed. The reported macroseismic effects may vary (one or two levels, up or down) depending on the characteristics of local geology or buildings. If not expressly indicated, earthquake perception is intended during the day. Peak ground acceleration is expressed in cm/s².
Values and terms do not coincide with other seismic scales.
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Nearby cities 3 Km far from the epicenter:
La Habra
10- Harmful earthquake 150 < PGA < 300 ( VII MCS )
Seismic shake is very strong; people who drive on bumpy roads may not feel it. The event is preceeded by an intense and wide roar, often heard inside buildings. All objects, mirrors, glasses, fall down and break inside houses; furniture moves. People panic and run outside. There are just a few victims and injured. The structure of old houses and monuments is damaged; big cracks in walls; doors and windows break; tiles and chimneys break and fall. Ordinary buildings have shallow damages and can be accessed. A few cracks on the ground; only a few roads get damaged. Even if the situation is serious, a lot of reports come from the affected area.
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Nearby cities from 3 Km to 11 Km far from the epicenter:
Brea, Fullerton, La Miranda, Whittier, Rowland Heights
9- Strong earthquake 80 < PGA < 150 ( VI MCS )
Seismic shake is intense and only a few people, inside moving vehicles, can’t feel it. The event is preceeded by a roar, often heard even inside the houses; who sleeps, wakes up. Furniture and objects vibrate loudly; unsteady objects fall. Doors and windows open and close. Chandeliers oscillate widely. People are terrified and run out of buildings. Someone gets hurt or is suddenly taken ill. Old buildings are damaged: cracks in walls; broken windows; broken chimneys. Ordinary buildings are not particularly damaged. A high number of reports arrive through the internet.
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Nearby cities from 11 Km to 21 Km far from the epicenter:
Yorba Linda, El Monte, Santa Ana, West Covina, Garden Grove, Downey
8- Notable earthquake 40 < PGA < 80 ( V MCS )
Inside the houses almost everyone feels the earthquake, and sometimes even the preceeding roar; outside many perceive a vibration. Seismic shake is intense and wakes up several people. Objects vibrate, some of them fall. Chandeliers oscillate widely. Doors and windows open and close. People are scared and run out of buildings. Old houses and monuments are lightly damaged. Several reports arrive from the affected area.
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Nearby cities from 21 Km to 36 Km far from the epicenter:
Los Angeles, Long Beach, Pasadena, Huntington Beach, Irvine, Ontario, Pomona, Corona
7- Moderate earthquake 20 < PGA < 40 ( IV MCS )
Inside the houses, many people feel the earthquake. Seismic vibration is very intense and wakes up who’s sleeping. Chandeliers oscillate widely. Windows and objects shake;People are scared; many of them get out of buildings. Outside many people clearly feel the earthquake and hear the preceeding roar. Buildings are not externally damaged. Many reports arrive from the affected area.
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Nearby cities from 36 Km to 60 Km far from the epicenter:
Riverside, Santa Monica, San Bernardino, Glendale, Torrance, Mission Viejo
6- Mild earthquake 10 < PGA < 20 ( III – IV MCS )
Lots of people inside buildings feel a strong seismic vibration. Chandeliers oscillate noticeably; crakles and tinkles can be heard. Someone of those who sleep, wakes up. Several people prefer to go outside, as a safety measure. Outside several people feel the vibration, they clearly hear that particular sound preceeding the earthquake. Many reports arrive through the internet.
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Nearby cities from 60 Km to 99 Km far from the epicenter:
Thousand Oaks, Temecula, Santa Clarita, Hemet, Lancaster, Victorville, San Clemente, Hesperia
5- Light earthquake 5 < PGA < 10 ( III MCS )
Inside buildings, some people feel a vibration. Chandeliers oscillate; A tinkle of glasses shattered can be heard. Someone decides to go outside, as a safety measure. Outside only a few people feel the earthquake; before the event, a few people hear a noise, like a far away thunder. From the affected area many reports arrive.
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Nearby cities from 99 Km to 164 Km far from the epicenter:
San Diego, Ventura, Barstow, Palm Springs, Escondido, Indio, California City
4- Weak earthquake 2.5 < PGA < 5.0 ( II – III MCS )
A relevant number of people, inside buildings in in quietness, feels a moderate vibration. Chandeliers oscillate; a tinkle of glasses shattering can be heard. People who perceive these effects feel apprehension. Outside, only a few people feel the earthquake; someone hears a low frequency noise. A few reports arrive through the internet.
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Nearby cities from 164 Km to 270 Km far from the epicenter:
Bakersfield, Tijuana, Mexicali, Ensenada, Santa Barbara, Delano, Caliente
3- Tenuous earthquake 1.2 < PGA < 2.5 ( II MCS )
In the higest and middle floors, a few people perceive a light vibration. Chandeliers oscillate. People feel apprehension. Outside, almost nobody feels the earthquake.From the affected area, only a few reports arrive; sometimes a light sound is heard.
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Nearby cities from 270 Km to 446 Km far from the epicenter:
Las Vegas, Fresno, Henderson, Visalia, Nipton, Yuma, Clovis, Salinas, Kingman
2- Insignificant earthquake 0.6 < PGA < 1.2 ( I – II MCS )
In the highest floors and in quietness, a few people feel a very light vibration, but there isn’t any concern. Outside nobody feels anything. No sound of the earthquake can be heard. Only a few reports arrive through the internet.
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Nearby cities from 446 Km to 735 Km far from the epicenter:
Phoenix, San Francisco, San Jose, Tucson, Sacramento, Reno, Santa Rosa
1- Unperceivable earthquake 0.3 < PGA < 0.6 ( I MCS )
The intensity is irrelevant; the earthquake is recorded by seismic stations in the region. Even in the best-case scenario, almost nobody feels the shaking, not even in the highest floors. No reports come from the area.
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Cities beyond 735 Km from the epicenter.
0- Instrumental earthquake PGA < 0.3 ( I MCS )
Earthquake is unsubstantial; it is recorded by seismic stations with advanced instruments. Even in the best-case scenario, people don’t feel the earthquake.
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