The Canterbury, New Zealand, Network and CUSP Strong Motion Seismographics

Speaker:
John B Berrill,
University of Canterbury, and
Canterbury Seismic Instruments Ltd.,
Christchurch, New Zealand
(www.csi.net.nz)Seminar Abstract:Motivated by an expected ~M8 rupture on the Alpine Fault, New Zealand, the engineering seismology group at Canterbury University sought to install a strong-motion network of about 80 instruments in the region. The Canterbury Network (CanNet), now part of the NZ national network, GeoNet, has three main components:
1. A dense array of 15 to 20 instruments to capture details of the rupture mechanism.
2. A network of 40 instruments distributed across the central South Island to record regional attenuation.
3. A local network to study the response of the highly variable 20–25 m layer of post-glacial soil beneath the city of Christchurch.
In order to deploy such a number of instruments at affordable cost, the group collaborated with the Electrical Engineering Department of the University to design a low-cost digital accelerograph. The original 12-bit CUSP-3A (CUSP: Canterbury University Seismograph Project) accelerograph, designed to put more points on the map for a fixed budget and low maintenance costs, has been evolved to the 13-bit CUSP-3B and the 17-bit CUSP-3C instrument. Both instruments are web-based for ease of monitoring and down loading of data and, where possible, use off-the-shelf components such as industrial single-board computers and MEMs accelerometers. At this time (February 2007), about half the CanNet instruments have been installed.For the past 15 months, a central-recording system, CUSP-M, developed for monitoring structural response, has been undergoing trials in a building on campus, and will be installed in several structures throughout NZ. It uses the web-based communications of the 3B/C instruments, simple Ethernet wiring to connect up to 32 three-component sensors to the central unit and features digitization at the sensor and synchronized sampling. A hardened version will be employed for the dense, rupure-mechanism array.The speaker is conscious of the isolation of his group on their South Seas islands, and invites your feedback on this program and the instruments.

Audiences: Everyone Is Invited

Contact: Evangeline Reyes