DOI: 10.5061/dryad.3n5tb2rsj
title: Geodetic constraints of strain partitioning across the Pacific Northwest, USA

description: At the Cascadia subduction zone, the Juan de Fuca plate (JdF) subducts
 obliquely under, and deforms, the North American plate (NA). Subduction
 deformation dominates deformation on land, as observed by geodetic
 measurements such as the Global Navigation Satellite System (GNSS,
 including GPS), limiting the resolution of deformation due to surface
 faults on the overriding North American plate. A kinematic block model
 applied to oblique JdF-NA convergence interprets deformation in terms of
 microplate rotations and elastic deformation on locked and partially
 locked faults, revealing partitioning between surface faults in the
 Pacific Northwest region and the subduction zone interface. Beginning with
 an initially dense block model, an L1 regularization known as Total
 Variation Regularization (TVR) algorithmically selects the most active
 faults. We find a tradeoff between megathrust activity and surface fault
 activity: A megathrust constrained to dip-slip-only requires more active
 surface faults along with greater fault slip rates than a freely slipping
 (oblique) megathrust. However, even with a dip-slip-only megathrust,
 trench-parallel strike-slip faults near the trench are neither active nor
 form a simple forearc sliver. Furthermore, estimated slip rates in models
 with a freely slipping subduction zone are more consistent with geologic
 slip rates than those models with a constrained dip-slip subduction zone.
 In other words, oblique subduction is sufficient to explain onshore GNSS
 observations or geologic slip rates, and strain partitioning between a
 dip-slip megathrust and strike-slip hanging-wall faults is not required
description: # Geodetic Analysis of Strain Partitioning across the Pacific Northwest,
 USA
 [https://doi.org/10.5061/dryad.3n5tb2rsj](https://doi.org/10.5061/dryad.3n5tb2rsj) This repository contains additional details of total variation regularization (TVR) results for the 6 block model results and an Excel sheet of the fault slip rates. The required inputs are in the repository as block folder, mesh folder, segment data, command textfile, and station data. These folders are the output results and block model inputs as described in the Block format ([https://github.com/jploveless/Blocks/wiki](https://github.com/jploveless/Blocks/wiki)). The 6 different block model results are identified as follows:  ## List of the block model results (folders) Reference models are the models used to describe the results. Comparison models include the higher λ and lower λ as shown in the paper. Each folder contains information on the velocities of the respective block model results (Mod), Residual (Res), Observation (Obs), Rotation (Rot), and Strain (Strain).  | Folders | Type | | :------ | :----------------------------------------------------------------- | | 1919 | Reference model for dip-slip subduction ((λ = 1600) | | 2078 | Reference model for oblique-slip subduction (λ = 3400) | | 1932 | Comparison model for dip-slip subduction (higher λ) (λ = 2900) | | 2113 | Comparison model for oblique-slip subduction (higher λ) (λ = 6900) | | 1904 | Comparison model for dip-slip subduction (lower λ) (λ = 550) | | 2058 | Comparison model for oblique-slip subduction (lower λ) (λ = 1400) | ## Description of block model inputs Block folder - contains the blocks used in our study Segment folder - contains the faults used in our study Mesh folder - contains the Cascadia mesh used in our study  Station folder - contains the GNSS data used in our study Cascadia_final.command - is a textfile containing the parameters used to run the block modeling ### Description of Excel sheet (Observed slip rates - Cascadia project) This excel sheet contains the compliation of fault slip rates described in our model and NSHM faults. Units of fault slip rates are in mm/yr. Faults are described in the respective fault codes used in the block models.