Ashleigh (Ash) Matheson

Ash wearing a hi-vis jacket and standing in front of snow-capped mountains.

Contact

Email: ash.matheson@vuw.ac.nz

Office: CO421

Qualifications

Diploma in Performing Arts, UCOL (2013)

BSc in Physics, Massey University (2020)

BA in English, Massey University (2020)

BSc with Honours in Geophysics, Victoria University of Wellington (2021)

MSc Candidate in Geophysics

Research Interests

Seismology, Geodesy

MSc thesis

Title

Modelling Earthquake Sources in Aotearoa Using Joint Analysis of Seismological and Geodetic Data.

Supervisors

- Prof John Townend

- Dr Calum Chamberlain

Project objectives and description

Aotearoa is located along the boundary of the Pacific and Australian tectonic plates, making it vulnerable to large and potentially damaging earthquakes. Modelling the source processes of these earthquakes is critical in understanding how they are generated and in mitigating earthquake-related risks. The robustness of an earthquake source model can be improved by the inclusion of multiple independent datasets: in particular, the differing sensitivities and geometries of seismic and geodetic datasets can be combined in ‘joint’ inversions to generate enhanced source models.

Moment tensor solutions are routinely produced for earthquakes in Aotearoa via analysis of broadband seismometer waveforms alone. For large earthquakes (e.g., the Darfield, Christchurch, Cook Strait, and Kaikōura earthquakes in recent years), ad hoc models incorporating multiple datasets are often published by different groups, but the wide variety of modelling methods employed in some cases renders comparisons between different seismic events difficult.

My objective is to develop a semi-automatic method of computing robust seismic source models routinely for all shallow moderate-to-large earthquakes in Aotearoa. My models incorporate broadband and strong-motion data from GeoNet’s national seismometer network in conjunction with static geodetic displacements from GeoNet GNSS receivers and high-rate geodetic data from the PositioNZ network. Ideally, this modelling method will produce robust earthquake source models with meaningful uncertainties for all source parameters - enabling meaningful comparison between earthquakes in Aotearoa, and improving the quality and size of the source model catalogue.