1811-12

On December 16, 1811, the 400 terrified residents of New Madrid, Missouri, are abruptly awakened by the first of three magnitude 8 earthquakes and thousands of aftershocks to rock the region in the winter of 1811-12. These three quakes are some of the most powerful in U.S. history. The shaking actually rings church bells in Boston, Massachusetts—1,000 miles away.

More than 3,500 earthquakes have been recorded east of the Mississippi River since 1700.

1906

An 8.25 magnitude quake strikes San Francisco at 5:13 a.m. on April 18, 1906. Hundreds or thousands of people die when the ground liquefies beneath tenements and causes them to collapse. Most of those buildings immediately catch fire, and trapped victims cannot be rescued. A huge fire burns for four days. The total earthquake death toll is estimated at more than 3,000 from all causes. Damage is estimated at $500 million in 1906 dollars.

The shock is felt from Oregon to Los Angeles and east to central Nevada, an area of about 375,000 square miles, approximately half of which is in the Pacific Ocean. The affected region extends about 400 miles from the southern part of Fresno County to Eureka, and for 25 to 30 miles on either side of the fault zone.

1920s

Scientists recognize that earthquakes occur in specific zones.

1927

For the first time, provisions for seismic design are included in the Uniform Building Code (UBC).

1935

UBC seismic section includes a map showing "Zones of approximately equal seismic probability," leading to 60+ years of grouping seismic requirements primarily by geographic location.

1964

On March 27, 1964 at 5:36 p.m., a magnitude 9.2 earthquake, the largest ever recorded in the northern hemisphere, strikes in Alaska, causing extensive damage. It also triggers a Pacific-wide tsunami that causes damage in Western Canada, Oregon, California and the Hawaiian islands, and even registers in Cuba and Puerto Rico. Crescent City, California is hit by a 21-foot wave.

1971

A 6.6 magnitude quake strikes at 6:01 a.m. on February 9, 1971 in the San Fernando region. It is one of the most devastating earthquakes in California history. Three hospitals are badly damaged, including Olive View Hospital, where a number of newly constructed reinforced concrete buildings are very seriously damaged or collapse, causing several deaths.

1983

The states of Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri, and Tennessee form the Central United States Earthquake Consortium (CUSEC). CUSEC coordinates multi-state planning for earthquake preparedness, response, and recovery, encouraging research in earthquake hazard reduction.

1994

The 6.7 magnitude Northridge earthquake strikes on January 17, 1994 at 4:31 a.m., its epicenter in Northridge, California, a suburb of Los Angeles in the San Fernando Valley. Total damage is estimated at $15 billion. But 57 dead and 1500 serious injuries are low. Why? This is one of the best prepared areas in the world. Although advances in seismic design reduced damage compared to the 1971 quake, building code officials, government scientists and others recognize that current seismic design is insufficient.

1994

The National Earthquake Hazard Reduction Program (NEHRP), which produces seismic hazard maps and publishes seismic recommendations for new buildings and rehabilitating old buildings, responds to the 1994 Northridge quake. NEHRP is a partnership of the Federal Emergency Management Administration, United States Geological Survey, National Institute of Standards and Technology, and the National Science Foundation. NEHRP's "Recommended Provisions for the Development of Seismic Regulations for New Buildings" includes soil condition in its design control factors.

1995

With U.S. Geological Survey (USGS) collaboration, CUSEC state geologists complete a regional soils map that can be used to locate areas likely to experience intense shaking in earthquakes, part of an effort to map earthquake hazards. Most CUSEC states have adopted building codes containing modern earthquake design standards.

1997

The UBC recognizes that soil effects must be included in seismic design, but the 1997 UBC continues to base requirements on the zone in which a structure is located.

2000

The International Building Code (IBC) 2000 adopts NEHRP requirements, including a very complex determination for calculating the seismic construction standards for individual buildings. Seismic requirements are no longer determined just by geographic area, but by a combination of factors, including soil condition and building usage.