Publication Date:
2014-07-03
Description:
The 2013 Cook Strait earthquake sequence began on the 18th July 2013 with two foreshocks of Mw 5.7 and Mw 5.8 and culminated in the Mw 6.6 Cook Strait and Lake Grassmere events on the 21st July and 16th August respectively. Located ∼ 50 km south of New Zealand's capital, Wellington, the earthquakes generated the most significant ground shaking in the Wellington and Marlborough regions in recent decades. During the first event, located under Cook Strait, continuously recording GPS instruments across central New Zealand recorded up to 5 cm of horizontal displacement. Modelling suggests that the rupture was 25 km long with up to 90 cm of dextral strike slip. The second event, located 20 km to the south west, caused displacements of up to 25 cm at GPS sites located around the Clifford bay area. In addition, two interferograms from RADARSAT-2 and TerraSAR-X showed up to 30 cm of Line-of-Sight displacement in the vicinity of Lake Grassmere. Modelling indicates predominantly dextral strike slip of up to 2.1 m. Coulomb Stress changes induced by the earlier foreshocks suggest that the Cook Strait event was triggered by the preceding events and that the Lake Grassmere event was subsequently triggered by the Cook Strait earthquake.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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