# Robust Estimation of Earthquake Magnitude in Indonesia Using PGD Scaling Law from Regional High-Rate GNSS Data

## TL;DR

This paper presents a new method to estimate earthquake magnitudes in Indonesia using high-rate GNSS data, improving early tsunami warnings.

## Contribution

A regional PGD scaling law using HR-GNSS data is developed to improve magnitude estimation for large earthquakes in Indonesia.

## Key findings

- The PGD-derived magnitudes show strong agreement with catalog magnitudes, with a MAD of 0.21.
- MPGD estimates converge within 2–3 minutes for well-recorded events and remain robust for large earthquakes.
- The method complements conventional seismic networks for more reliable early warning systems.

## Abstract

The accurate and timely estimation of earthquake magnitude is essential for effective tsunami early warning, particularly in seismically active regions such as Indonesia. Conventional seismic approaches are often hindered by magnitude saturation in significant events (Mw > 7.5), resulting in systematically underestimated magnitudes. To address this limitation, we develop a regional peak ground displacement (PGD) scaling law using high-rate GNSS (HR-GNSS) data from 21 moderate to large earthquakes in Indonesia. Based on 87 PGD observations, we construct a regression model that relates PGD, hypocentral distance, and moment magnitude (Mw). The PGD-derived magnitudes (MPGD) exhibit strong concordance with catalog moment magnitudes, achieving a mean absolute deviation (MAD) of 0.21 and surpassing the accuracy of previously published global models. Retrospective analyses reveal that MPGD estimates converge within 2–3 min for well-recorded events and remain robust, even for great and tsunamigenic earthquakes. These results underscore the potential of HR-GNSS data to complement conventional seismic networks, providing rapid and reliable magnitude estimates for operational tsunami early warning in Indonesia.