Why Southern California is going to have a major earthquake

Friday, March 10 is the anniversary of Long Beach earthquake in 1933, the deadliest California quake in 100 years.
Let's take a look at our chances of another massive disaster.
2017 FORECAST
The U.S. Geological Survey earthquake forecast maps show the risk of human-activity-induced earthquakes in Oklahoma are now as high as natural occurring earthquakes in California. Before 2016, the USGS maps identified hazards only from natural earthquakes.

CALIFORNIA CONCERNS
The U.S. Geological Survey 2014 earthquake forecast indicates that the likelihood of a moderate earthquake – between magnitude 6.5 and 7.5 – has decreased, but the chance of a higher-magnitude quake in the region has increased.
Plate movement
The rate of plate movement along the San Andreas fault is approximately 1.3 inches each year – about the same rate your fingernails grow. A USGS report released March 2 detailed a study of the southern San Andreas fault. The study found evidence of 10 ground-rupturing earthquakes between magnitude 7.0 and 7.5 between 800 A.D. and 1857. Predictions based on the survey forecast a 16 percent chance of a magnitude 7.5 or larger earthquake near Kern County in the next 30 years.
Prediction models
The USGS cautions that although its most recent prediction model is vastly improved since the version in 2008, it is still an approximation. The USGS uses two kinds of scientific models to predict earthquake probability.
1. The earthquake rupture forecast shows where and when the earth might slip along the state’s many faults.
2. The ground motion prediction model estimates the subsequent shaking given by one of the fault ruptures.
The color-coded data are the state’s forecast from 2014.

STATE OF SHAKE

In the late 1980s, the USGS monitored 16 faults (the main ones). In 1994, the 6.7 Northridge earthquake occurred on an unrecognized fault line. The quake is said to be the costliest earthquake in U.S. history, and scientists began to search and monitor many other fault lines in the state.

The USGS estimates long-term quake hazards to give communities an assessment of risk in their area. More than two-thirds of the nation’s annualized earthquake losses in property and structures will be in California, and in California, 80 percent of the losses will be in these 10 counties:
Top 10 counties by estimated annualized earthquake loss (percent of state total)
1. Los Angeles (30.6%)
2. Santa Clara (8.9%)
3. Alameda (8%)
4. Orange (7%)
5. San Bernardino (6%)
6. Riverside (5.6%)
7. Contra Costa (4.6%)
8. San Francisco (3.8%)
9. San Mateo (3.5%)
10. San Diego (3.3%)

DEADLY QUAKES
The John Muir School in Long Beach, above, was damaged by a magnitude-6.4 earthquake on March 10, 1933. More than 230 school buildings were damaged by the quake that struck at 5:54 p.m. The devastation prompted the state to enact a series of earthquake building codes including one that mandated all school buildings be earthquake resistant.

Sources: U.S. Geological Survey, California Department of Conservation, Los Angeles Public Library, Working Group on California Earthquake Probabilities


http://www.ocregister.com/articles/infographic-746097-earthquake-fault.html