![]() In the United States, the first regional seismic networks were begun by research institutions and universities like Caltech University of California, Berkeley and the University of Washington. The backbone of an earthquake early warning system is a widespread and robust network of seismometers. Scientists deployed an analog system to notify first responders of impending earthquake activity as they worked on rescue efforts at the Cypress Viaduct collapse in Oakland, CA. Retired seismologist David Oppenheimer reflects on the first prototype earthquake early warning system used during the 1989 Loma Prieta earthquake. During its six months of operation, the system sent warnings for 12 earthquakes greater than magnitude 3.7. So USGS scientists set up a temporary system that radioed alerts to the workers whenever there was a significant aftershock that might shake the Nimitz. As rescuers worked to free people trapped in the rubble, the risk of aftershocks damaging the freeway further and injuring the workers became apparent. The intense shaking from the mainshock of Loma Prieta collapsed a 1.6-mile (2.5-kilometer) section of the Nimitz Freeway (referred to as the “Cypress Structure”) along I-880 through Oakland. However, a few years later, other USGS scientists would temporarily use some of Heaton’s innovative ideas after the Loma Prieta earthquake to try to safeguard the lives of rescue workers in the Bay Area. Heaton’s pioneering insight was ahead of its time, but the technology available in 1985 was not adequate for the system he proposed. In the United States, the first serious proposal for such a system came from USGS geophysicist Tom Heaton in 1985. Calls echoing that desire continued throughout the 20 th century in countries as far off as Iran, Italy, Japan, and Mexico. Even as far back as 1868, following a magnitude 6.8 earthquake on the Hayward fault, the San Francisco Daily Evening Bulletin published an editorial proposing an early warning system. ![]() Wherever people live with earthquakes, there is a desire for an early warning that shaking is imminent. The epicenter was located near Loma Prieta peak in the Santa Cruz Mountains, approximately 14 km (9 mi) northeast of Santa Cruz and 96 km (60 mi) south-southeast of San Francisco and Oakland (Credit: H.G. Aerial view of collapsed sections of the Cypress Street viaduct of Interstate Highway 880 in Oakland, California, damaged as a result of the magnitude 6.9 Loma Prieta earthquake on October 17, 1989. ![]()
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