First result from the GEONET real-time analysis system (REGARD): the case of the 2016 Kumamoto earthquakes

Kawamoto, Satoshi; Hiyama, Yohei; Ohta, Yusaku; Nishimura, Takuya

doi:10.1186/s40623-016-0564-4

Cited by 44 publications

(39 citation statements)

References 21 publications

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“…The 2016 Kumamoto earthquake ( M j 7.3) occurred on 16 April 2016 (Japan Standard Time, +9 GMT), which was the first large inland earthquake with M > 7 after the launch of the REGARD system. During the earthquake, the REGARD system successfully modeled the coseismic displacements and estimated finite fault models consistent with postprocessed models [ Kawamoto et al ., ]. This result demonstrates the potential of GNSS‐enhanced EEW systems because finite fault models should improve hazard information by providing the spatial extent of the fault.…”

Section: Discussionmentioning

confidence: 99%

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REGARD: A new GNSS‐based real‐time finite fault modeling system for GEONET

et al. 2017

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The short‐period seismometer‐based magnitude saturation problem, especially for events with magnitude > 8, can be improved by a real‐time Global Navigation Satellite System (GNSS) positioning technique, which has enabled rapid estimation of a finite fault model for a large earthquake without any saturation. A new real‐time fault modeling system based on the GNSS Earth Observation Network (GEONET) is developed and is under experimental operation in Japan. In this paper, we present the newly developed system REGARD (the Real‐time GEONET Analysis system for Rapid Deformation monitoring), which consists of real‐time GNSS positioning, automatic detection of coseismic displacement by the event, and quasi real‐time finite fault model inversion routines. The performance of the automatic event detection system is tested through experimental real‐time operation based on GEONET data for 2 months. Furthermore, we also test the reliability of the finite fault model inversion routines using real raw GNSS data observed for past large earthquakes: the 2003 Tokachi‐oki earthquake (moment magnitude (Mw) 8.3), the 2011 Tohoku earthquake (Mw 9.0), and the 2011 off‐Ibaraki earthquake (Mw 7.7). A simulated 1707 Hoei‐type Nankai Trough earthquake (Mw 8.7) is also tested. The real‐time experimental operation shows that real‐time GNSS positioning is precise enough to detect all the tested earthquakes, and the inversion results demonstrate that the REGARD can reliably estimate the earthquake size and its extent within 3 min after the origin time. These results suggest that the REGARD system will complement the seismometer‐based magnitude determination system.

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Section: Discussionmentioning

confidence: 99%

“…As denoted in section 1, challenges for GNSS augmentation to EEW systems have already started in the United States, e.g., GlarmS [Grapenthin et al, 2014] and G-FAST [Crowell et al, 2016]. For a further study on the results for the 2016 Kumamoto earthquake, see Kawamoto et al [2016].…”

Section: Future Prospects Of the Regard Systemmentioning

confidence: 99%

REGARD: A new GNSS‐based real‐time finite fault modeling system for GEONET

et al. 2017

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“…So far, many aforementioned GNSS approaches and related publications are based on post-event processed data and implementation. To our knowledge, real-time inversion of earthquakes just using GNSS is only feasible in regions where there is a dense GNSS network (Kawamoto et al 2016(Kawamoto et al , 2017, while a global GNSS-based earthquake source inversion system has never been reported except post-event demonstration in simulated environment.…”

Section: Introductionmentioning

confidence: 99%

Automated GNSS and Teleseismic Earthquake Inversion (AutoQuake Inversion) for Tsunami Early Warning: Retrospective and Real-Time Results

Chen

Liu

Song

2019

Pure Appl. Geophys.

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Rapid finite fault source determination is critical for reliable and robust tsunami early warnings. Near-field Global Navigation Satellite System (GNSS) observations have shown value to constrain the source inversion, but real-time GNSS stations are sparse along most of the active faults. Here we propose an automatic earthquake finite source inversion (AutoQuake Inversion) algorithm jointly using near-field (epicentral distance \ 1000 km) GNSS data and mid-range (epicentral distance from 30°to 45°) teleseismic P displacement waveforms. Neither the near-field GNSS nor the mid-range teleseismic data clip or saturate during large earthquakes, while the fast-traveling P-waves are still essential to constrain the source in regions where very few or no GNSS stations are available. Real-time determination of the fault geometry remains to be the main challenge for rapid finite source inversion. We adopt a strategy to use the predefined geometry Slab2 for earthquakes within it or to forecast a focal mechanism based on nearby historical events for earthquakes without Slab2 prior. The algorithm has been implemented successfully in the prototype of JPL's GPS-Aided Tsunami Early-Detection system and tested for many real events recently. This article provides the framework of the algorithm, documents the retrospective and real-time results, and discusses remaining challenges for future improvements.

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“…Applications of this newly deployed technique to the Kumamoto earthquake sequence are presented in this issue. Kawamoto et al (2016) show the ability of the GNSS-based real-time analysis system (REGARD) deployed by the Geospatial Information Authority (GSI) to detect coseismic displacements and estimate size and location of the source fault. Kodera et al (2016) examine the performance of the current seismic-based earthquake early warning system operated by the Japan Meteorological Agency (JMA) and indicate that two improved methods will be implemented in the near future.…”

Section: Open Accessmentioning

confidence: 99%