Alva Review-Courier -

PHOENIX (AP) — On May 3, 1887, a magnitude 7.6 earthquake struck Arizona from across the Mexico border just south of Douglas. Newspapers, letters and other documents reveal the Pitaycachi quake shook a 770,000-square-mile area (2 million square km.) extending from Prescott to Yuma to El Paso, Texas.

"The surface fracturing and movement was recorded over a distance of about 41 kilometers and had several segments to it," said Dave Brumbaugh, director of the Arizona Earthquake Information Center at Northern Arizona University.

The largest quake known to have ever occurred in the Basin and Range P...