Professor Gerald Roberts co-authors new paper explaining what influences earthquake recurrence
A new paper in Nature Geosciences examines how earthquakes are driven by viscous flow of the Earth's mantle
Professor Gerald Roberts is an author on a new paper in Nature Geosciences that explains how earthquakes are driven by viscous flow of the Earth's mantle. The paper uses measurements of the rate of slip on active faults in the Italian Apennines, correlating these with measurements of topography within these mountains. It is demonstrated that forces associated with uplift of the mountains derived from viscous flow at depth produce a power-law increase in strain rate that is best explained by plastic flow in shear zones beneath the brittle fault zones that host devastating earthquakes.
Caption: Fault scarp offsetting a slope dating from 15,000 years ago in central Italy. It is offsets such as this that define the strain-rates that we have correlated with topography. The offsets have developed over tens of earthquakes, each with a slip of <~1m so the correlation holds over a timescale including tens of earthquakes.
Professor Roberts explains:'It is critical to convince local populations that earthquakes are not random events. This study shows that the rate of earthquake recurrence and its geographic variation are controlled by viscous flow whose geography and character are well-known. This is a step towards communicating the fact that earthquakes are not chance events, but are in fact inevitable phenomena that populations should plan for.'
The paper (Viscous roots of active seismogenic faults revealed by geologic slip rate variations) was published on the 3rd November 2013.