The Arias intensity (IA) is a measure of the strength of a ground motion.[1] It determines the intensity of shaking by measuring the acceleration of transient seismic waves. It has been found to be a fairly reliable parameter to describe earthquake shaking necessary to trigger landslides.[2] It was proposed by Chilean engineer Arturo Arias in 1970.
It is defined as the time-integral of the square of the ground acceleration:
(m/s)where g is the acceleration due to gravity and Td is the duration of signal above threshold. Theoretically the integral should be infinite.[3]
The Arias Intensity could also alternatively be defined as the sum of all the squared acceleration values from seismic strong motion records.[2]
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