Evaluating the reliability of phones as seismic monitoring instruments

Emergency responders must "see" the effects of an earthquake clearly and rapidly for effective response. This project is a novel use of cell phone and information technology to measure ground motion intensity parameters. The phone sensor, however, is an imperfect device and has a limited operational range. Thus, shake table tests were performed to evaluate their reliability as seismic monitoring instruments. Representative handheld devices, either rigidly connected to the table or free to move, measured shaking intensity parameters well. Bias in 5%-damped spectral accelerations measured by phones was less than 0.05 and 0.2 [log(g)] during 1-D and 3-D shaking in frequencies ranging from 1 to 10 Hz. They did tend to overestimate the Arias Intensity, but this error declined for stronger motions with larger signal to noise ratios. With these ubiquitous measurement devices, a more accurate and rapid portrayal of the damage distribution during an earthquake can be provided.