Laser strainmeters: New developments and earthquake prediction applications

Abstract

Two novel laser strainmeters furnished with airfilled pressure-tight shielding pipe are considered to be an affordable tool for modern geodynamic observations. The thermal-to-strain coefficient of 1 · 10 −8 K −1 provides sufficient long-term instrument stability, while short-term sensitivity of ΔL/ L = 10 −11–10 −12 in the frequency band up to 1 kHz has been achieved. Experimental prototypes of the laser strainmeters have been tested at various sites and certain phenomena concerning earthquake prediction problems have been revealed.