Arias intensity explained

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:

IA=

\pi
2g
Td
\int
0

a(t)2dt

(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]

Notes and References

  1. New predictive equations for Arias intensity from crustal earthquakes in New Zea . Journal of Seismology. 13. 1. 31–52 . 2009JSeis..13...31S . 10.1007/s10950-008-9114-2.
  2. Web site: 7. Seismic landslide hazard zonation . Faculty of Geo-Information Science and Earth Observation of the University of Twente . 2006-09-29 . 2010-12-12 . https://web.archive.org/web/20100815092518/http://www.itc.nl/ilwis/applications/application07.asp . 2010-08-15 . dead .
  3. Web site: Earthquake-Triggered Landslides in Austria – Dobratsch Revisited . https://web.archive.org/web/20110531193712/http://www.geologie.ac.at/filestore/download/JB1471_193_A.pdf . dead . 2011-05-31 . Wolfgang A. Lenhardt . Jahrbuch der Geologischen Bundesanstalt . 2007 .