RAPID MAGNITUDE ESTIMATION OF THE AUGUST 5, 2018, LOMBOK EARTHQUAKE USING HIGH-RATE GNSS DATA

Abstract

The rapid estimation of the magnitude of an earthquake is an essential part of an earthquake early warning system (EEWS), which is used to respond to earthquake shaking and the possible arrival of a tsunami. This research is the first in Indonesia to use Global Navigation Satellite System (GNSS) as part of an EEWS. Three high-rate GNSS datasets were processed using the precise point positioning post-processing method, which resulted in a peak ground displacement (PGD) and peak ground velocity (PGV) value due to the Lombok earthquake on August 5, 2018. The results showed that the magnitude of the PGD from the station closest to the earthquake source (KDOO) was Mw 6.6 within eight seconds of the original time, while that at the farthest location (CMAT) reached Mw 6.9 within 18 seconds of the original time. At the CMAT station, we also estimated the magnitude using PGV, which showed results consistent with the PGD data. These results confirm the potential use of the PGD and PGV data obtained from high-rate GNSS to estimate earthquake magnitudes rapidly as part of an EEWS.