Research on the 1989 Loma Prieta, California, earthquake, probably the most thoroughly documented in American history, has dramatically improved our understanding of the complexity of earthquakes and of how society can reduce risk and improve response in connection with large natural disasters. The magnitude 6.9 earthquake was the largest and most damaging to strike an American urban area since the 1906 San Francisco earthquake. Loma Prieta's 10th anniversary is October 17.

Loma Prieta began without immediate foreshock activity about 100 km southeast of San Francisco (37°03.6′N, 121°88.3′W) on October 17, 1989, at 5:04 p.m. PDT (00:04:15.2 UTC., October 18).The quake killed 63 people, and another 350 were hospitalized. Estimates of total property losses range from $6 billion to $10 billion. Its dramatic timing, interrupting the World Series in San Francisco, and its striking images—a pancaked freeway, a fallen span of a major transbay bridge, and burning collapsed apartments—piqued public interest. It also prompted the U.S. Congress to authorize supplemental funding to the National Earthquake Hazards Reduction Program (NEHRP) agencies—USGS, National Science Foundation, Federal Emergency Management Agency and National Institute of Standards and Technology—to support research in order to learn from the tragedy.