Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Relationship between anthropogenic surface waves and vehicle number. Total horizontal strain for the daytime hours recorded by a Lower Sand Hill Road DAS channel versus the number of vehicles detected by template matching. Two frequency bands are shown, f = 4.0–10.0 Hz (squares) and f = 15.0–30.0 Hz (triangles). The energy of surface waves produced by vehicles decays with decreasing wavelength and increasing propagation length; hence, the correlation improves at higher frequencies.
