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Coupling and Seismic Cycle Along the Hikurangi Subduction Zone

Description: 

Here, we study the Hikurangi subduction zone (North Island of New Zealand) from Nov. 2014 to Jan. 2022. InSAR studies in New Zealand are particularly challenging due to the dense vegetation cover. The numerous crop fields generate strong biases in the multilooked time series results. These biases can reach several centimeters in amplitude and can be mixed with the tectonic signals. We present a powerful strategy to mitigate these biases and correct their impact on our observations as much as possible. We correct this fading signal using a principal component analysis (PCA). This approach is applied directly to the displacement time series rather than the interferograms. We demonstrate how a PCA applied to the displacement time series can separate the spatial long-wavelength, the coherent tectonic signal, from the localized biases. We observe that this latter method yield is more reliable in reducing the impact of these environmental biases than the masking method.
Furthermore, it allows us to isolate the interseismic signal across the Hikurangi subduction zone. Using these corrected displacement time series, we then study the inter-SSE period following the Kaikoura earthquake (Nov. 2016, Mw 8.1) to observe if this crustal earthquake has impacted the long-term plate coupling. We integrate the InSAR velocity map to compute a coupling model of the inter-SSE period. We then can extract and observe the signal from the Slow Slip Events (SSEs) and propose a first slip model using both InSAR and GNSS time series to obtain the slip at depth.

Session: From Earthquakes to Plate Boundaries: Insights Into Fault Behavior Spanning Seconds to Millennia

Type: Oral

Date: 4/20/2023

Presentation Time: 02:45 PM (local time)

Presenting Author: Louise Maubant

Student Presenter: No

Invited Presentation: 

Authors