2018 – Probability of Surface Faulting from an Earthquake Affecting a Vulnerable Structure

Russell Cuthbertson and Leanne Capewell

While structures such as a dam walls, pipelines, gas storage tanks, and nuclear facilities are vulnerable to the shaking from earthquakes, they are even more susceptible to differential movement on faults passing beneath their foundations.

In the past, the probability of surface rupture of a fault was calculated by making some simplistic assumptions about the distribution of earthquake magnitudes. Improved databases of earthquake ground faulting now allow the probability of surface rupture to be estimated in a more realistic fashion. Computing software that uses a Monte Carlo approach has been developed to allow the effect of various scenario choices on rupture probability to be investigated.
Using this software, it is found that the most significant influence on rupture probability is the long-term fault slip-rate. Other assumptions about the faulting style, maximum magnitude and conversion parameters have only a moderate influence on the results.

There have been several instances in recent history in Australia of surface faulting due to earthquakes, but there has been only limited damage to infrastructure due to the remoteness of these earthquakes. The software that has been developed will allow a considered assessment and comparison of the hazard and risk due to both ground shaking from earthquakes and from surface rupture.

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