Optical Measurements of Temperature and Strain of New Zealand’s Alpine Fault

Date: 4/24/2019

Time: 08:30 AM

Room: Grand Crescent

The Alpine Fault of southern New Zealand is a major plate boundary fault that produces large earthquakes approximately every 300 years and last ruptured in 1717AD. There is thus considerable interest in studying this fault for both scientific and practical reasons. In 2013 a program began to drill into the Alpine Fault at Whataroa in NZ where the fault is relatively shallow (about 1000 metres below the surface) and this was completed in 2014. As part of this project a fibre optical cable was cemented to the side of the borehole where it remains allowing passive monitoring of the fault.We will also present in this talk our initial measurements of the temperature profile down the borehole and how it correlates with the sub-surface geological features. Repeated temperature measurements over time will allow us to see how the fault changes in response to seismic activities elsewhere. In addition we have performed an active seismic survey near the borehole and can compare the strain measurements taken using the fibre to those from more traditional acoustic sensors. Finally we will discuss our designs for making a suitable sensing head that is compact, solar powered, and highly reliable. Such a sensor head would find widespread applications not only in geophysical monitoring but also structural health monitoring etc.

Presenting Author: Neil G. R. Broderick

Authors