Publication Date

2017-5

Document Type

Honors Thesis

Degree Name

Bachelor of Arts

Department

Geosciences

Advisors

Jack P. Loveless

Keywords

Cascadia, subduction, Slow slip event, Earthquake, Tremor, GPS, Algorithm, Total variation regularization, Olympic Penisula (Wash.), Cascadia subduction zone, Global positioning system

Abstract

Slow slip events (SSEs) are a form of aseismic strain release at subduction zones characterized by a temporary reversal in interseismic upper plate motion, frequently accompanied by seismic tremor. In the northern segment of the Cascadia subduction zone, SSEs occur every 10-16 months and are geodetically detected using continuous GNSS station position time series. This study developed and applied a slope comparison-based detection algorithm to determine dates and displacement vectors of SSEs at individual GNSS stations. We invert for slip distribution estimates for SSEs between 1997 and 2015 using two regularization techniques: Smoothing and total variation regularization (TVR). TVR yields compact, sharply bordered slip estimates which align well with down dip limits of coupling on the plate interface and with spatial ranges of tremor during each event. TVR gives another view of slow slip that can contribute to understanding of the parameters of slip generation.

Language

English

Comments

53 pages 230 unnumbered pages : color illustrations, color map. Includes bibliographical references (pages 52-53)

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