Using 1-Hz GPS data to measure deformations caused by the Denali fault earthquake

Area of Science:

• Geophysics
• Seismology
• Geodesy

Background:

• The 2002 Denali fault earthquake (Mw 7.9) produced substantial surface displacements and widespread seismic waves.
• Traditional seismic instruments faced limitations in capturing the full amplitude and frequency of these waves.

Purpose of the Study:

• To assess the efficacy of high-frequency Global Positioning System (GPS) in recording seismic wave data from a major earthquake.
• To compare GPS-derived displacement data with traditional strong ground-motion records.

Main Methods:

• Integration of strong ground-motion records to derive displacement data.
• Analysis of 1-hertz GPS position estimates collected at varying distances from the earthquake epicenter.
• Detection and analysis of seismic surface waves using 1-hertz GPS receivers.

Main Results:

• Good agreement was found between integrated strong ground-motion data and GPS-derived displacement estimates near the epicenter (140 km).
• 1-hertz GPS receivers successfully detected seismic surface waves up to 3800 km away, surpassing the dynamic range of saturated seismic instruments.
• High-frequency GPS demonstrated a broader dynamic range and frequency bandwidth for ground-motion observations.

Conclusions:

• High-frequency GPS is a valuable tool for observing seismic surface waves, especially when traditional instruments saturate.
• GPS technology enhances the study of earthquake processes by providing detailed ground-motion data over extended distances and frequencies.