Uncertainty in Ground-Motion-to-Intensity Conversions Significantly Affects Earthquake Early Warning Alert Regions

• DOI: 10.1785/0320240004
• Publication Date: 2024-05-16T13:53:02Z
• Authors: Jessie K. Saunders; Annemarie S. Baltay; Sarah E. Minson; Maren Böse
• Keywords: Intensity; Earthquake warning system

Abstract We examine how the choice of ground-motion-to-intensity conversion equations (GMICEs) in earthquake early warning (EEW) systems affects resulting alert regions. find that existing GMICEs can underestimate observed shaking at short rupture distances or overestimate extent low-intensity shaking. Updated remove these biases would improve accuracy regions for ShakeAlert EEW system West Coast United States. uses ground-motion prediction (GMPEs), which calculate spatial distributions peak ground acceleration (PGA) and velocity (PGV) from source estimates, combined with to translate GMPE output into modified Mercalli intensity (MMI). significant epistemic uncertainty distances; near-source MMI estimates different differ by over 1 unit, extents used public alerts hundreds kilometers larger magnitude earthquakes (M ∼6.5+). use a catalog “Did You Feel It?” reports evaluate well predict Our preferred GMICE is one computes using PGV high intensities transitions PGA nondamaging intensities. These results motivate updating relationships more generally, including ShakeMap applications.