BeckerFraserPhotos May 2013 photograph 142

Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "Digging out the basement of the ANZ building in Cathedral Square".

Waterhouse

Images, eqnz.chch.2010

The basement of the "Price Waterhouse" building after demolition after the Christchurch earthquakes...

Photograph by Jennifer Middendorf 404

Images, UC QuakeStudies

Seen through the cordon fence, water fills the former basement of the ANZ building on Hereford Street.

BeckerFraserPhotos May 2013 photograph 149

Images, UC QuakeStudies

The PricewaterhouseCoopers demolition site on Armagh Street viewed through a barbed wire fence. Water has filled the basement area.

Photograph by Jennifer Middendorf 407

Images, UC QuakeStudies

Seen through the cordon fence, a digger sits on a mound of dirt, and water fills the former basement of the ANZ building on Hereford Street.

BeckerFraserPhotos May 2013 photograph 143

Images, UC QuakeStudies

The demolition site of the ANZ Building. A digger sits behind a pile of rubble, and water fills the former basement. The former post office can be seen in the background.

BeckerFraserPhotos May 2013 photograph 031

Images, UC QuakeStudies

A view over the top of a cordon fence. A digger sits on a mound of dirt, and water fills the former basement of the ANZ building on Hereford Street. The partially-demolished BNZ building can be seen in the background.

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.