Imaging the 2016 Mw 7.8 Kaikoura, New Zealand, earthquake with teleseismic P waves: A cascading rupture across multiple faults

The 13 November 2016 Mw 7.8 Kaikoura, New Zealand, earthquake was investigated using teleseismic P waves. Backprojection of high‐frequency P waves from two regional arrays shows unilateral rupture of at least two southwest‐northeast striking faults with an average rupture speed of 1.4–1.6 km/s and t...

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Bibliographic Details
Published in:Geophysical research letters 2017-05, Vol.44 (10), p.4790-4798
Main Authors: Zhang, Hao, Koper, Keith D., Pankow, Kristine, Ge, Zengxi
Format: Article
Language:English
Subjects:
2016 Kaikoura earthquake
Arrays
backprojection
Bursting strength
Cascading
cascading rupture
Duration
Earthquakes
Elastic waves
Energy
Energy distribution
Fault lines
Faults
finite fault model
Imaging techniques
Movement
multiple faults
P waves
peak ground acceleration
Rupture
Rupturing
Seismic activity
Shaking
Slip
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Summary:The 13 November 2016 Mw 7.8 Kaikoura, New Zealand, earthquake was investigated using teleseismic P waves. Backprojection of high‐frequency P waves from two regional arrays shows unilateral rupture of at least two southwest‐northeast striking faults with an average rupture speed of 1.4–1.6 km/s and total duration of ~100 s. Guided by these backprojection results, 33 globally distributed low‐frequency P waves were inverted for a finite fault model (FFM) of slip. The FFM showed evidence of several subevents; however, it lacked significant moment release near the epicenter, where a large burst of high‐frequency energy was observed. A local strong‐motion network recorded strong shaking near the epicenter; hence, for this earthquake the distribution of backprojection energy is superior to the FFM as a guide of strong shaking. For future large earthquakes that occur in regions without strong‐motion networks, initial shaking estimates could benefit from backprojection constraints. Key Points Unilateral rupture to the northeast with an average velocity of 1.4–1.6 km/s and total duration of ~100 s Multiple faults within the Marlborough system were activated during the rupture Peak ground acceleration near the source is better correlated with areas of short‐period energy release than with areas of large slip
ISSN:0094-8276
1944-8007
DOI:10.1002/2017GL073461