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Ambient Seismic Noise Studies of the Alpine Fault, New Zealand

Description: 

The Alpine Fault has been identified as the primary seismic hazard in Southern New Zealand since it ruptures in M7-8 earthquakes as regularly as every ∼300 years and last ruptured in 1717 AD. Empirical information about how the ground shaking will affect New Zealand after a large Alpine Fault earthquake does not exist as no such Alpine Fault earthquakes have yet been recorded instrumentally. Ambient seismic noise is a new field in seismology that allows us to study wave propagation in areas of interest without the need of an earthquake or explosions. Ambient noise typically appears random and incoherent in seismograms, but it has been demonstrated experimentally and theoretically that the cross-correlation of ambient seismic noise recorded at two seismic stations can reveal coherent energy travelling between stations. The resulting cross-correlation function can provide an estimate of the Green’s function between those stations. This analysis allows us to retrieve the propagation properties of seismic waves over long paths using noise records alone. A good understanding of the ambient noise field is vital for both time-travel and amplitude measurements. We perform a noise analysis of the West Coast of New Zealand to characterise the ambient noise field using records from permanent and temporary networks, including SALSA (Southern Alps Long Skinny Array), a new temporary network of broadband seismometers deployed every ∼10 km between Milford Sound and Maruia following the Alpine Fault trace. This analysis will allow us to perform travel-time analysis (ambient noise tomography) and amplitude analysis (Virtual Earthquakes).

Session: Advancing Science With Global Seismological and Geophysical Networks [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Ilma del Carmern C. Juarez Garfias

Student Presenter: Yes

Invited Presentation: 

Authors