Earthquake hazard assessments to critical engineered structures are conducted by Probabilistic Seismic Hazard Analysis (PSHA). The predicted rate at which a specific seismic ground motion parameter is exceeded at a site is utilised for safety regulations and design standards of infrastructure such as dams, bridges and nuclear facilities. It is paramount that empirical data is utilised to validate PSHA estimates of large magnitude, low frequency ground motions.
Precariously balanced rocks (PBRs) possess a high susceptibility to toppling during earthquakes, thus their preservation in seismically active regions allows unexceeded ground motions to be constrained. PBRs uniquely provide palaeo-seismic data over long earthquake reoccurrence timescales of 1ka–1Ma, capturing events where there is an absence of instrumental recordings.