The answer depends on what is being monitored. The key is to remember that
whereever the seismograph is, that is what is being monitored. If the
seismograph is coupled to the ground, then ground vibration is being monitored.
If the seismograph is on a porch, then the response of the porch is being
monitored.
According to the ISEE Seismograph User Guidelines, the sensor should be placed on or in the ground on the side of the structure towards the blast. A structure can be a house, pipeline,
telephone pole, etc. Measurements on driveways, walkways, and
slabs are to be avoided where possible. If in soil, the soil should be
undisturbed or compacted. If near a structure, it should be placed within
10 feet (0.3 meters) or less than 10% of the distance from the blast, whichever
is less. |