Response of test house to vibroseis vibrations and environmental forces

In response to public concerns about the damage potential of vibroseis vibrations from seismic exploration, Fina Oil and Chemical Company (now Total E&P USA, Inc.) sponsored full-scale testing of a typical residence. The test house was vibrated by four vibroseis trucks on both soil and asphalt surfaces at declining separation distances. Ultimately, the vibrators were 13 feet (4.0 m) from the front porch and 10 feet (3 m) from the front sidewalk. Peak particle velocities of the ground motions were about 1 in./second (0.4 cm/second) at the house foundation. As expected, the responses of the superstructure were strongly dependent on the frequencies of the ground motions. No damage to the house of any kind was produced by these vibrations, even though the vibrators were operating at 90% maximum output. Tests were also conducted away from the house to explore the vibration intensities and attenuation characteristics of the ground motions generated. The resulting vibrations were compared to previous work and found to be consistent with those results. Changes in crack width and associated weather-induced changes in temperature, humidity, and other environmental factors were recorded every 2 hours for 1 year. Environmental effects are known to produce larger crack responses than vibrations that conform to common standards and regulated limits, a fact demonstrated again in this case. Response motions in the house were also recorded during common household activities, including hammering nails, slamming doors, and use of the fireplace. In the vicinity of the input forces, some of these activities generated greater response than did the vibroseis excitation.