An experienced seismologist can then interpret the collected records to map the underground formation contours.
She found a penciled map of the underground tunneling system at Columbia University.
"Berliners learn of the Russian advances by the crossing out of places on maps in the underground.
Another was a detailed map of the underground utility tunnels near the embassy, with the access points to the embassy's two water intake pipes highlighted.
We already tested you with the subway signs and street patterns, now what about the geographically accurate maps of the underground metro systems?
Engineers must redraw old city maps of the underground from the 1930's, removing items like trolley electricity systems that no longer exist and adding several utilities, including Verizon, Con Edison and the city's Department of Environmental Protection, which controls the water system.
And so, like a species adapting to a new environment, they have begun to map out the underground portions of the subway that signals will penetrate: parts of the stations at 34th Street and Eighth Avenue, for example, or on the shuttle platform at Grand Central Terminal.
Probes will scan the entire Green over two days to build up a map of the underground graves and buildings.
The roundel and the map made the Underground a brand which has "spawned its iconic status", said Nikki Crumpton, chief strategy officer for advertising agency McCann-Erickson London.
In prioritising clarity over geography, the electrical engineer's map of the underground triggered a revolution in the way transit routes were represented.
