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Seismological and Hydrogeological Controls on New Zealand-Wide Groundwater Level Changes Induced by the 2016 Mw 7.8 Kaikōura Earthquake

journal contribution
posted on 09.02.2021, 07:26 by KC Weaver, SC Cox, John Townend, H Rutter, IJ Hamling, C Holden
© 2019 K. C. Weaver et al. The 2016 Mw 7.8 Kaikōura earthquake induced groundwater level changes throughout New Zealand. Water level changes were recorded at 433 sites in compositionally diverse, young, shallow aquifers, at distances of between 4 and 850 km from the earthquake epicentre. Water level changes are inconsistent with static stress changes but do correlate with peak ground acceleration (PGA). At PGAs exceeding 2 m/s2, water level changes were predominantly persistent increases. At lower PGAs, there were approximately equal numbers of persistent water level increases and decreases. Shear-induced consolidation is interpreted to be the predominant mechanism causing groundwater changes at accelerations exceeding 2 m/s2, whereas permeability enhancement is interpreted to predominate at lower levels of ground acceleration. Water level changes occur more frequently north of the epicentre, as a result of the fault's northward rupture and resulting directivity effects. Local hydrogeological conditions also contributed to the observed responses, with larger water level changes occurring in deeper wells and in well-consolidated rocks at equivalent PGA levels.

History

Preferred citation

Weaver, K. C., Cox, S. C., Townend, J., Rutter, H., Hamling, I. J. & Holden, C. (2019). Seismological and Hydrogeological Controls on New Zealand-Wide Groundwater Level Changes Induced by the 2016 Mw 7.8 Kaikōura Earthquake. Geofluids, 2019, 1-18. https://doi.org/10.1155/2019/9809458

Journal title

Geofluids

Volume

2019

Publication date

01/01/2019

Pagination

1-18

Publisher

Hindawi Limited

Publication status

Published

ISSN

1468-8115

eISSN

1468-8123

Article number

UNSP 9809458

Language

en