National Strong Motion Project
Detailed Description
The 1989 Loma Prieta earthquake (magnitude 6.9) set San Francisco’s Transamerica Pyramid swaying and rocking. An array of 22 sensors (small arrows) recorded horizontal movement on the 49th floor of the building five times greater than the 1.5 inches measured in the basement, as indicated by the recordings (red lines).
Sources/Usage
Public Domain.