Two figures in the report are very telling as to the concentration of earthquakes and implications on "Shaking expected for Tall Structures Like Bridges" (below)...
as well as a graphic showing the chance of human-induced and natural earthquakes. (Look at the concentration around Oklahoma presumably due to Fracking.)
The report approaches these issues in a FAQ approach...so, here are some quick highlights:
Key Comments in the Report
Q: What Are the Components of Seismic Risk?
A: Seismic risk to a highway system is determined by three factors:
- Likelihood of seismic events of varying magnitudes, and related physical events, often referred to as the hazard;
- Vulnerability of highway structures to damage from such events; and
- Potential consequences of that vulnerability (e.g., lives lost, economic disruption, etc.)