Contemporary and Paleoliquefaction Induced Lateral Spreading in Christchurch New Zealand

Jeffrey L. Bachhuber, Gregory P. De Pascale, Ellen Rathje, michael Little, Peter Almond, Christian Ruegg, & Michael Finnemore

Submitted August 15, 2018, SCEC Contribution #8689, 2018 SCEC Annual Meeting Poster #225

Earthquake triggered liquefaction and lateral spreading was widespread in Cantebury New Zealand during the 2010 to 2012 Cantebury earthquake sequence (CEF) and lead to $20 billion NZ dollars damage. Although the causes and timing of liquefaction during the CEF are well known, the geologic controls on lateral spreading are more poorly understood. We undertook a multi-disciplinary investigation funded by the National Science Foundation (NSF)and explored lateral spreading in Christchurch using image-differencing displacement maps, shear wave velocity profiles, boreholes and cone penetration soundings (CPT), and paleoseismic trenching combined with radiocarbon dating. Preliminary results suggest that cumulative displacements are less than those observed in the trench by downdropped blocks within the lateral spread and index beds in the subsurface which when combined with clear paleoliquefaction at the site (e.g. faulted pre-CES sandboils) suggest at least one major pre-CES lateral spreading event here. We feel this can be a powerful screening and mapping tool for identifying locations susceptible to lateral spreading to combine with typical geotechnical engineering methods.

Key Words
Paleoliquefaction, Christchurch, Lateral Spreading

Citation
Bachhuber, J. L., De Pascale, G. P., Rathje, E., Little, m., Almond, P., Ruegg, C., & Finnemore, M. (2018, 08). Contemporary and Paleoliquefaction Induced Lateral Spreading in Christchurch New Zealand. Poster Presentation at 2018 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Geology