11:00 AM - 11:15 AM
[G01-6-03] Near real time modelling of coseismic and post-seismic deformation for NetworkRTK applications
Deformation patterns that result from large earthquakes manifest as instantaneous coseismic and time-dependent post-seismic motion. For example, the deformation caused by the November 2016 Kaikoura Mw 7.8 resulted in coseismic displacements up to several metres while continuing post-seismic displacements have amounted to 20-30 cm after 3 months. Such events deform the geodetic infrastructure, which for the 2016 Kaikoura event, can be detected over 600 km from the epicenter.
Surveying applications, such as Network RTK, require precise relative and current epoch coordinates that are typically based on an International Terrestrial Reference Frame (.e.g. ITRF2008, ITRF2014). Although the latest ITRF realisation (ITRF2014) incorporates post-seismic decay for selected ITRF sites, commercial software that generates time-dependant coordinates assumes linear motion and cannot (currently) deal with non-linear motion. Abrupt changes in position i.e. coseismic displacement; are relatively easy to deal with – a new updated coordinate is computed. However, transient and non-linear motion such as that caused by post-seismic relaxation and slow slip events are more difficult to model and therefore predict.
Correcting the positions of NetworkRTK sites requires the development of low latency models of both the coseismic and post-seismic deformation. Traditionally dislocation models of earthquakes are available months or years after an earthquake but advances in instrumentation and processing algorithms means that models are available in near real time. As shown by the 2016 Kaikoura event, the post-seismic motion is evolving over time and therefore up to date positioning data is required to model the transient motion accurately. Although early models may not necessarily have the accuracies of the final models, it should be possible to make regular updates as additional data becomes available.
Surveying applications, such as Network RTK, require precise relative and current epoch coordinates that are typically based on an International Terrestrial Reference Frame (.e.g. ITRF2008, ITRF2014). Although the latest ITRF realisation (ITRF2014) incorporates post-seismic decay for selected ITRF sites, commercial software that generates time-dependant coordinates assumes linear motion and cannot (currently) deal with non-linear motion. Abrupt changes in position i.e. coseismic displacement; are relatively easy to deal with – a new updated coordinate is computed. However, transient and non-linear motion such as that caused by post-seismic relaxation and slow slip events are more difficult to model and therefore predict.
Correcting the positions of NetworkRTK sites requires the development of low latency models of both the coseismic and post-seismic deformation. Traditionally dislocation models of earthquakes are available months or years after an earthquake but advances in instrumentation and processing algorithms means that models are available in near real time. As shown by the 2016 Kaikoura event, the post-seismic motion is evolving over time and therefore up to date positioning data is required to model the transient motion accurately. Although early models may not necessarily have the accuracies of the final models, it should be possible to make regular updates as additional data becomes available.