Differential Lidar Derived Geometry and Kinematics of the Papatea Fault (Kaikoura, New Zealand)
Date: 4/25/2019
Time: 09:15 AM
Room: Puget Sound
Differential lidar derived surface displacements provide a unique way of parametrizing shallow fault geometry and estimating fault dip. This is especially useful in regions with sparse field measurements like the Papatea fault of the 2016 Mw 7.8 Kaikoura (New Zealand) earthquake. From fault perpendicular profiles in the E-W, N-S and vertical displacement directions, we measured fault offsets to compute local slip vectors at short intervals along the fault. Since the fault strike is known and the slip vectors lie in the plane of the fault, we calculate dip. Thus, we illustrate our estimations of fault dip and offset magnitude at profiled locations along strike of the Papatea fault. Here, fault dip inferences are especially valuable because only one measurement of fault dip has been collected in the field along the main strand. Although this fault likely played a fundamental role in the northeastward propagation of the Kaikoura earthquake, the Papatea fault is often left out of or parametrized inappropriately in kinematic rupture models. We estimate a maximum fault displacement of ~11 m with an average of 8-9 m along the main strand, exceptionally high for such a short (19 km-long) fault. Our results indicate the Papatea fault has an average fault dip of 70-75ºW along the main strand, significantly steeper than the single field dip measurement of 51ºW. Lastly, from far-field displacements, near the south end of the Papatea fault, we estimate a shallower-angle subsurface dip of ~25-40ºW, implying a complex non-planar shape. Our findings emphasize the utility of high resolution lidar topography in parametrizing surface ruptures and demonstrate the detail preserved using this geodetic method.
Presenting Author: Anna Diederichs
Authors
Anna Diederichs adiederi@uvic.ca University of Victoria, Victoria, British Columbia, Canada Presenting Author
Corresponding Author
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Edwin Nissen enissen@uvic.ca University of Victoria, Victoria, British Columbia, Canada |
Lia Lajoie llajoie@mymail.mines.edu Colorado School of Mines, Golden, Colorado, United States |
Differential Lidar Derived Geometry and Kinematics of the Papatea Fault (Kaikoura, New Zealand)
Category
Advances in Tectonic Geodesy