California Earthquakes

Through an historical perspective

San Francisco

Loma Prieta

San Fernando

Northridge

Long Beach

1933 Long Beach Earthquake

• March 10,1933, 5:54 PM• Mw = 6.4• Right lateral slip along Newport-Inglewood

Fault• No surface rupture• 120 fatalities• 50 million dollars in damage

Newport-Inglewood Fault

Franklin Junior High School120 schools destoyed; 70 damaged

Collapse of unreinforced masonry structures

Pile of Bricks

Collapse of Unreinforced Masonry School

• 5 teachers killed• Field Act passed• Gave the state authority to supervise

structures built for schools

1971 San Fernando Earthquake

• February 9, 1971, 6:01 AM• Thrust fault dipping to the north• 12 miles of surface rupture• Maximum displacement of 6 feet• 65 fatalities• 500 million dollars of damage

Location, San Fernando Valley

• Cross-sections of the San Fernando and Northridge earthquakes.

San Fernando Valley Earthquakes

Dam: end terminus of the Los Angeles water system; 80 % of LA’s water

Shaking caused landslide

80,000 people below

House over Garage

Veterans Hospital

Olive-View Hospital (soft story collapse)

1989 Loma Prieta Earthquake

• October 17, 1989; 5:04 PM• Mw = 6.9• Oblique movement on the San Andreas Fault• Maximum offset of 3-4 feet• ~ 25 miles of fault plane movement• 15 seconds of shaking• 6-10 billion dollars of damage

Earth Materials

The Northridge Earthquake

• January 17. 1994, 4:31 am• Epicenter: 1 mile SW of Northridge• Magnitude: Mw 6.7• Type of fault: blind thrust, the Pico Thrust• Hypocenter: 18.4 km• Deaths: 57• 1500 seriously injured• Cost: 15 billion dollars

The mountains are the surface expression of the fault. This fault was unknown before this earthquake.

Northridge Earthquake

Collapse of Soft Story

Failure of Reinforced Concrete Structures

Rebuilt Olive-view Hospital

Success of retrofitted URM

structures

Change in how earthquake insurance is distributed.