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Crustal Fault Connectivity of the M w 7.8 2016 Kaikōura Earthquake Constrained by Aftershock Relocations
Author(s) -
Lanza F.,
Chamberlain C. J.,
Jacobs K.,
WarrenSmith E.,
Godfrey H. J.,
Kortink M.,
Thurber C. H.,
Savage M. K.,
Townend J.,
Roecker S.,
EberhartPhillips D.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl082780
Subject(s) - aftershock , seismology , geology , subduction , seismometer , crust , fault (geology) , upper crust , tectonics , geophysics
Abstract The 14 November 2016 M w 7.8 Kaikōura earthquake in the northern South Island, New Zealand, involved highly complex, multifault rupture. We combine data from a temporary network and the permanent national seismograph network to repick and relocate ~2,700 aftershocks of M≥3 that occurred between 14 November 2016 and 13 May 2017. Automatic phase‐picking is carried out using REST, a newly developed hybrid method whose pick quality is assessed by comparing automatic picks for a subset of 138 events with analysts' picks. Aftershock hypocenters computed from high‐quality REST picks and a 3‐D velocity model cluster almost exclusively in the shallow crust of the upper plate and reveal linkages at depth between surface‐rupturing fault segments. Only eight aftershocks are relocated on a deeper structure positioned between patches of geodetically detected afterslip. This indicates that afterslip has not triggered significant earthquake activity on the subduction interface during the period of aftershock activity analyzed.