Determination of Short-term and Long-term Relaxation Times of Postseismic Deformation and Their Spatial Variability Using GNSS Trajectory Models
Loading...
Date
2025-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
Extended trajectory models of geodetic stations are a vital tool for assessing the geodynamic processes of the Earth. Postseismic transient deformation can be modeled using a double logarithmic transient function, and daily observations from several stations affected by a seismic event. One transient representing the short-term deformation, the days to weeks after an event, and the other representing the long-term deformation, the months to years after an event. This study works to determine the best pair of transient values that minimize the residuals of the model for the 2011 Mw 9.1 Tohoku-Oki earthquake. Previous studies indicate there is a geographic correlation between the transient values and the distance from the earthquake’s epicenter. The values are first found via a grid search and then amplitudes are plotted and analyzed to view any spatial patterns in the results. From the values plotted according to their latitude and longitude, no clear spatial pattern was viewed in the T1 or T2 values. The plotted amplitudes show some correlation in the T1 amplitudes, with more negative values closer to the earthquake, and a stronger geographic correlation in the T2 amplitudes, with higher positive values closer to the earthquake. When the stations with higher residuals are removed, a stronger spatial correlation is observed. These results suggest that either the T1, or short-term component of the deformation is not being modeled as well due to the algorithm down weighting the first several weeks after the event or that a single relaxation time may fit the data for this earthquake.
Description
Keywords
Geodesy, Postseismic Deformation, Trajectory Models, GNSS