Mobile Phones and Social Media Empower the Citizen Seismologist
Monday, 15 December 2014
Emergency responders must “see” the effects of an earthquake clearly and rapidly for effective response. Mobile phone and information technology can be used to measure ground motion intensity parameters and relay that information to emergency responders. However, the phone sensor 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 one-dimensional (1-D) and three-dimensional (3-D) shaking in frequencies ranging from 1 Hz to 10 Hz. They did tend to over-estimate the Arias Intensity, but this error declined for stronger motions with larger signal-to-noise ratios. Additionally, much of the data about infrastructure performance and geotechnical effects of an earthquake are lost soon after an earthquake occurs as efforts move to the recovery phase. A better methodology for reliable and rapid collection of perishable hazards data will enhance scientific inquiry and accelerate the building of disaster-resilient cities. Post-earthquake reconnaissance efforts can be aided through the strategic collection and reuse of social media data and other remote sources of information. This is demonstrated through their use following the NSF-sponsored GEER response to the September 2013 flooding in Colorado. With these ubiquitous measurement devices in the hands of the citizen seismologist, a more accurate and rapid portrayal of the damage distribution during an earthquake may be provided to emergency responders and to the public.