Photograph by Paul Corliss 2991

Images, UC QuakeStudies

A photograph captioned by Paul Corliss, "NZEI poster and Save the Cathedral sticker. Corner Oxford Terrace and Bangor Street, Avon Loop".

Photograph by Paul Corliss 2989

Images, UC QuakeStudies

A photograph captioned by Paul Corliss, "NZEI poster. Corner Oxford Terrace and Bangor Street, Avon Loop".

Photograph by Paul Corliss 2990

Images, UC QuakeStudies

A photograph captioned by Paul Corliss, "NZEI poster and Save the Cathedral sticker. Corner Oxford Terrace and Bangor Street, Avon Loop".

Photograph by Paul Corliss 2992

Images, UC QuakeStudies

A photograph captioned by Paul Corliss, "NZEI poster and Save the Cathedral sticker. Corner Oxford Terrace and Bangor Street, Avon Loop".

Photograph by Paul Corliss 2993

Images, UC QuakeStudies

A photograph captioned by Paul Corliss, "NZEI poster and Save the Cathedral sticker. Corner Oxford Terrace and Bangor Street, Avon Loop".

Ambient noise cross-correlation observations of fundamental and higher-mod…

Research papers, Victoria University of Wellington

Measurement of basement seismic resonance frequencies can elucidate shallow velocity structure, an important factor in earthquake hazard estimation. Ambient noise cross correlation, which is well-suited to studying shallow earth structure, is commonly used to analyze fundamental-mode Rayleigh waves and, increasingly, Love waves. Here we show via multicomponent ambient noise cross correlation that the basement resonance frequency in the Canterbury region of New Zealand can be straightforwardly determined based on the horizontal to vertical amplitude ratio (H/V ratio) of the first higher-mode Rayleigh waves. At periods of 1-3 s, the first higher-mode is evident on the radial-radial cross-correlation functions but almost absent in the vertical-vertical cross-correlation functions, implying longitudinal motion and a high H/V ratio. A one-dimensional regional velocity model incorporating a ~ 1.5 km-thick sedimentary layer fits both the observed H/V ratio and Rayleigh wave group velocity. Similar analysis may enable resonance characteristics of other sedimentary basins to be determined. © 2013. American Geophysical Union. All Rights Reserved.