WEMO ERT Set 1 - February 2011 - Photograph 91
Images, UC QuakeStudies
A photograph of a pile of sledge hammers in Latimer Square with various nicknames written in vivid on the handles.
A photograph of a pile of sledge hammers in Latimer Square with various nicknames written in vivid on the handles.
A photograph of a member of the Wellington Emergency Management Office Emergency Response Team using a sledgehammer to break open the window of a building in the Christchurch central city.
A photograph a box with supplies on top. These include tarpaulins, duct tape, a sledgehammer, a box of screws, and a brush and shovel.
A photograph of members of the Wellington Emergency Management Office Emergency Response Team and the New Zealand Police inspecting the Cherish Bridal and Formal Wear store on Montreal Street. Inside the store one of the ERT members is attempting to break through a wall.
Despite the relatively low seismicity, a large earthquake in the Waikato region is expected to have a high impact, when the fourth-largest regional population and economy and the high density critical infrastructure systems in this region are considered. Furthermore, Waikato has a deep soft sedimentary basin, which increases the regional seismic hazard due to trapping and amplification of seismic waves and generation of localized surface waves within the basin. This phenomenon is known as the “Basin Effect”, and has been attributed to the increased damage in several historic earthquakes, including the 2010-2011 Canterbury earthquakes. In order to quantitatively model the basin response and improve the understanding of regional seismic hazard, geophysical methods will be used to develop shear wave velocity profiles across the Waikato basin. Active surface wave methods involve the deployment of linear arrays of geophones to record the surface waves generated by a sledge hammer. Passive surface wave methods involve the deployment of two-dimensional seismometer arrays to record ambient vibrations. At each site, the planned testing includes one active test and two to four passive arrays. The obtained data are processed to develop dispersion curves, which describe surface wave propagation velocity as a function of frequency (or wavelength). Dispersion curves are then inverted using the Geopsy software package to develop a suite of shear wave velocity profiles. Currently, more than ten sites in Waikato are under consideration for this project. This poster presents the preliminary results from the two sites that have been tested. The shear wave velocity profiles from all sites will be used to produce a 3D velocity model for the Waikato basin, a part of QuakeCoRE flagship programme 1.