ShakeCast: Facilitating the Use of ShakeMap for Post-Earthquake Decision-Making and Response Within Caltrans and Other Critical Lifeline Communities

ShakeMap is a tool used to portray the extent of potentially damaging shaking following an earthquake. It can be used for emergency response, loss estimation, and public information. When a potentially damaging earthquake occurs, utility and other lifeline managers, emergency responders, and other critical users have an urgent need for information about the impact on their facilities so they can make appropriate decisions and take quick actions to ensure safety and restore system functionality. ShakeCast, short for ShakeMap Broadcast, is a fully automated system for delivering specific Advanced National Seismic System (ANSS) ShakeMap products to critical users, generating maps, and triggering established post-earthquake response protocols. ShakeCast allows utilities, transportation agencies, and other large organizations to automatically determine the shaking value at their facilities, set thresholds for notification of damage states (typically: damage unlikely, possible, or likely) for each facility, and then automatically notify (via pager, cell phone, or email) specified operators, inspectors, etc., within their organizations who are responsible for those particular facilities so they can prioritize response. The California Department of Transportation (Caltrans), a current ShakeCast user, is responsible for rapid assessment of thousands of overpasses and bridges. Hence, ShakeCast is a natural tool for providing Caltrans with an instantaneous snapshot of the likelihood of damage to each facility, allowing them to prioritize rerouting traffic, closures, and inspections following a damaging event. Caltrans evaluates potential impact using ShakeMap’s 1- and 3- Hz response spectral acceleration values, in conjunction with well established (Basoz and Mander) vulnerability functions based on National Bridge Inventory (NBI) structural characteristics. In general, highway and bridge transportation engineers are well situated to take advantage of the ShakeCast system since they are concerned about numerous facilities and they typically have knowledge of the seismic vulnerability of their structures, a requirement for rapid estimation of potential damage based on ShakeMap ground motion metrics. ShakeCast will also provide visualization tools showing both the distribution and likely damage states of the users structures, allowing rapid mapping, analyses, and reconnaissance and response planning.