Surface slip behavior of the southern and central Alpine fault, New Zealand

Jozi K. Pearson, & Nicolas C. Barth

Submitted August 15, 2016, SCEC Contribution #6980, 2016 SCEC Annual Meeting Poster #114

The Alpine Fault (AF) is a major continental plate boundary between the Australian and Pacific plates, linking oppositely-dipping subduction zones in New Zealand. Due to its relative geometric simplicity, high slip rate, and quasi-regular earthquake recurrence, the AF is a paradigm for characterizing “ideal” plate boundary behavior. It offers a stepping stone to understanding earthquake behavior on comparable but more complex systems such as the San Andreas Fault (SAF) System in California. A burgeoning record of more than ten paleoearthquakes on the AF spanning over four hundred kilometers of fault length reveals multi-mode earthquake behavior wherein some earthquakes propagate across section boundaries (e.g.: representing changes in geometry, slip vectors, and seismicity) and others appear to arrest at these locations. One critical section boundary is located between the southern and central AF sections. Through geomorphic analysis of high resolution light detection and ranging (lidar) data and supporting fieldwork on the southern and central sections of the AF, we aim to supplement the paleoseismic record with along-strike measurements of single earthquake surface displacements to determine spatiotemporal variations in slip accumulation and slip rate. We will also inform seismic hazards (specifically the location and width of surface rupture) and structural complexity, which may influence earthquake rupture propagation or arrest. Offset features will be dated by the following Quaternary dating methods: dendrochronology, optically stimulated luminescence (OSL), cosmogenic radionuclide (CRN), and/or Carbon-14 methods. The primary hypothesis is that surface rupture offsets along the AF will follow a uniform slip model in which repeating large earthquakes have essentially the same slip distribution in each event and that the total slip accumulation across the southern-central AF section boundary will have low spatiotemporal variation, which is consistent with previously determined slip rates and paleoearthquakes. Understanding slip distribution along the AF will clarify controls on continental plate boundary behavior, thus providing grounds for new research directions on other similar continental plate boundaries that exhibit more complexities and uncertainties.

Key Words
New Zealand, Alpine Fault, lidar, geomorphology, neotectonics

Citation
Pearson, J. K., & Barth, N. C. (2016, 08). Surface slip behavior of the southern and central Alpine fault, New Zealand. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Geology