Performance Evaluation of a Community-Engaged Low-Cost Earthquake Early Warning System for Aotearoa New Zealand

Abstract Can an effective earthquake early warning (EEW) system be implemented at a low cost in earthquake-prone regions? This study addresses this question by evaluating the feasibility of a low-cost, community-engaged EEW system in the Greater Wellington region of New Zealand. The system utilizes decentralized processing to run two algorithms: (1) NZ-PLUM, an adaptation of the propagation of local undamped motion approach tailored to New Zealand’s seismic context, and (2) NZ-PLUM-P, an enhanced version that incorporates P-wave detection for faster alerts. NZ-PLUM triggers alerts based on horizontal acceleration thresholds that are more sensitive to S waves, whereas NZ-PLUM-P offers a longer warning window by detecting the initial P waves. The system’s effectiveness is evaluated through an analysis of ambient noise in the community-hosted network, where 24 out of 27 stations exhibit low-to-medium noise levels. A false alert analysis confirms zero false alerts with both algorithms at an alerting threshold of Modified Mercalli intensity 5.0. The performance is further assessed using data from three recent local earthquakes: an M 3.9 event on 23 May, an M 4.1 event on 3 June, and an M 4.0 event on 6 July 2024. The results show that NZ-PLUM-P significantly improves warning times compared to NZ-PLUM, with average gains of 2.6, 1.25, and 6.4 s across five target points. These findings demonstrate the feasibility of implementing a low-cost, community-driven network capable of delivering effective EEWs. This approach presents a promising, cost-effective alternative for developing or enhancing EEW systems in earthquake-prone regions. Future research should focus on expanding the algorithms across the entire network, incorporating site amplification factors to refine intensity predictions, and increasing community engagement to further reduce noise and enhance system reliability.