Ground Acceleration Induced GNSS Satellite Loss-of-Lock During the 2016 M7.8 Kaikōura Earthquake, New Zealand

Session: Earthquake Early Warning: Current Status and Latest Innovations [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Over the last decade the Global Navigation Satellite Systems (GNSS) has provided significant insights in the retrospective analysis of dynamic motions during earthquakes. Techniques ranging from Central Moment Tensor (CMT) determination, peak-ground-displacement (PGD) scaling to magnitudes, to time-dependent finite fault slip inversions have been developed and applied to kinematic position time series analyses of earthquakes. Seismogeodetic analyses use high-rate geodetic observations to correct drift in strong motion instruments and provide position time series at accelerometer sampling rates. These techniques have been implemented into real-time GNSS analysis and modeling algorithms to augment earthquake early warning systems for large magnitude events with demonstrated operational success, for instance, during the 2014 Mw6.0 South Napa earthquake or the 2019 Ridgecrest sequence in California

A significant benefit attributed to GNSS is its ability to record and resolve ground motion precisely and provide a theoretically infinite dynamic range compared to, in particular, broadband seismic instrumentation. We show that during the 2016 Mw7.8 Kaikōura earthquake ground accelerations were large enough at the closest GNSS station KAIK that it lost lock of most GPS satellites – equivalent to a seismometer “clipping.” This can cause problems in real-time solutions as integer ambiguities will have to resolved again. Furthermore, real-time analysis techniques such as peak-ground-displacement inferred magnitude may be negatively affected. Utilizing receiver velocities and clock errors from time-differenced carrier phase observations, we can reliably detect such cycle slips without the need for additional modeling. Repair of these cycle slips is difficult as the station is shaking relatively unpredictably.

Presenting Author: Ronni Grapenthin

Authors