Predicting approximate seismic responses in multistory buildings from real-time earthquake source information, for earthquake early warning applications

Abstract

Regional earthquake early warning (EEW) alerts and related risk-mitigation actions are often triggered when the expected value of a ground-motion intensity measure (IM), computed from real-time magnitude and source location estimates, exceeds a predefined critical IM threshold. However, the shaking experienced in mid- to high-rise buildings may be significantly different from that on the ground, which could lead to sub-optimal decision-making (i.e., increased occurrences of false and missed EEW alarms) with the aforementioned strategy. This study facilitates an important advancement in EEW decision-support, by developing empirical models that directly relate earthquake source parameters to resulting approximate responses in multistory buildings. The proposed models can leverage real-time earthquake information provided by a regional EEW system, to provide rapid predictions of structure-specific engineering demand parameters that can be used to more accurately determine whether or not an alert is triggered. We use a simplified continuum building model consisting of a flexural/shear beam combination and vary its parameters to capture a wide range of deformation modes in different building types. We analyse the approximate responses for the building model variations, using Italian accelerometric data and corresponding source parameter information from 54 earthquakes. The resulting empirical prediction equations are incorporated in a real-time Bayesian framework that can be used for building-specific EEW applications, such as (1) early warning of floor-shaking sensed by occupants; and (2) elevator control. Finally, we demonstrate the improvement in EEW alert accuracy that can be achieved using the proposed models.

Earthquake Early Warning in Central America: The Societal Perspective

“…EEW can also provide early situational awareness for decision-makers, as strong shaking often causes cascading failures in key infrastructure systems (e.g., communication, power, transportation). Additionally, pre-programmed automated security actions such as the shut-down of nuclear reactors, deceleration of high-speed trains, bringing elevators to a stop at the nearest floor, can be implemented for engineering applications [9][10][11].…”

Developing a risk-informed decision-support system for earthquake early warning at a critical seaport

“…Many (if not all) existing operational EEW approaches (algorithms) employ relatively simplistic methods for determining when an alert should be issued [3]; decisions are typically based purely on a seismological threshold (such as magnitude or ground-motion amplitude) that are not adequately calibrated to capture/predict the impact of an incoming earthquake on the built environment [e.g., 4,5,6] and do not incorporate risk tolerance on the part of the end user(s). Maximising the utility of EEW requires the implementation of a formal decision support system (DSS) that explicitly accounts for the risk-and engineering-informed consequences of taking or not a particular risk-mitigation action, including the implications of unnecessarily raising an alarm, and stakeholder preferences/priorities towards different types of risks [7].…”