Characterizing the Complex Two N‐Wave Ionospheric Signature of the 2016 Kaikoura Earthquake

• Published in: Journal of geophysical research. Space physics 2018-12, Vol.123 (12), p.10,358-10,367
• Main Authors: Li, Justin D., Rude, Cody M., Pankratius, Victor
• Format: Article
• Language: English
• Subjects: 2016 Kaikoura earthquake; Atmosphere; Complexity; Earth; Earth atmosphere; Earth ionosphere; Earthquakes; Equator; GPS; Ionosphere; ionospheric disturbance; Ionospheric disturbances; Ionospheric electron content; Periodic variations; Perturbation; Seismic activity; Total Electron Content; Traveling ionospheric disturbances
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2018JA025376

Major earthquakes (>∼6.5 Mw) can generate observable waves which propagate not only through the Earth but also through the Earth's ionosphere. These traveling ionospheric disturbances can be observed using multifrequency GPS receivers to measure the ensuing perturbations in the Total Electron Content of the ionosphere. Assisted by a statistical approach we developed to indicate the occurrence of a significant TEC perturbation from the normal background behavior, we detect a traveling ionospheric disturbance generated by the 2016 7.8 Mw Kaikoura earthquake occurring in New Zealand on the 13th of November. The disturbance was detected ∼8 min after the earthquake, propagating toward the equator at ∼1 km/s with a peak‐to‐peak amplitude of ∼0.22 Total Electron Content units. The coseismic waveform exhibits complex structure unlike that of the expected N‐wave for coseismic ionospheric disturbances, with observations of oscillations with 4‐min periodicity and of two N‐waves. This observed complexity in the ionosphere likely reflects the impact of the complex, multifault structure of the earthquake. Plain Language Summary Earthquakes can produce waves that propagate through the charged layer of the Earth's atmosphere. Here we report on such an event caused by the 2016 Kaikoura earthquake in New Zealand. The appearance of the event was more complex than what is typically seen, which we attribute to the more complex structure of the earthquake itself. This may improve our understanding of how the atmosphere responds to earthquakes as well as other large scale types of events. Key Points We developed a statistical approach to detecting the occurrence of Total Electron Content disturbances The coseismic ionospheric disturbance event is characterized, driven by the schock-acoustic mechanism with complex, multiple N-wave behavior The complexity of the coseismic ionospheric disturbance suggests a link to the earthquake's complex structure