Abstract
On August 10 1993, at 09h 46m UT an earthquake of magnitude (ML) 6.4 occurred near Ormond, a locality to the north west of Gisbome in the North Island of New Zealand. The epicentre of the event was 38.52°S, 177.93°E, and had a focal depth of 48 km (Seismological Observatory, Institute of Geological and Nuclear Sciences Ltd.). Strong motion accelerographs at two sites on sediment in Gisborne recorded peak ground accelerations of 0.22 g at a distance of 20 km from the epicentre, while at Wairoa (80 km to the SW of the epicentre) 0.05 g was recorded, at Tolaga Bay (30 km to the NE of the epicentre) 0.09 g was measured [Pers. Comn. J. Zhou], and strong motion lasted for 5-10 s. Intensity of MMVI was observed in the Ormond area with pockets of MMVII, the later being based in particular on the presence of liquefaction.
Highlights
On August 10 1993, at 09h 46m UT an earthquake of magnitude (ML) 6.4 occurred near Ormond, a locality to the north west of Gisbome in the North Island of New Zealand
The sand boils lie beside a drain which is about 3 m below the terrace level which had approximately 200 mm of water flowing in it four days after the earthquake. The vents of these boils were aligned in a SE-NW direction, which is perpendicular to the nearby hills
A notable exception to the finer soil being liquefied last is seen at boil 61 where a medium brown sand overlies a thin layer of coarse grey silt
Summary
On August 10 1993, at 09h 46m UT an earthquake of magnitude (ML) 6.4 occurred near Ormond, a locality to the north west of Gisbome in the North Island of New Zealand. It is likely that many of the sites were just over the limit of liquefying and will be of great use in calibrating empirical models At those sites with a deep water table, liquefaction has necessarily occurred under high confining pressures, a condition for which there is a scarcity of data. The aim of this reconnaissance study was to document the extent of liquefaction and to record the location of individual sand boils and to obtain samples of ejecta, for more detailed future studies.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Bulletin of the New Zealand Society for Earthquake Engineering
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
