FUTURE EXPERIMENTS

From the preceeding discussion, I suggest the following modifications for future experiments of the two types described here:

• Passive seismic experiments
  • Conduct survey in an area with some geologic information at hand, and preferably data from a reflection seismic or drill-bit experiment available for comparison.
  • Use three-component geophones.
  • If a well is available, place phones down the well to make the array 3-D and provide some channels relatively insensitive to surface-traveling noise.
• Drill-bit experiments
  • Use a 2-D surface array, of three-component phones if possible.
  • Record ambient noise while the drill bit is not operating, preferably with other drilling-related machinery operating.
  • If a well near the borehole is available, place phones down the well to make the array 3-D.
• Other experiments. We have limited ourselves to two types of experiments in this discussion, but it may be interesting to consider other sources whose properties are similar to those discussed here. Some examples are geothermal energy, steam injection, and pumps.