Arias Intensity

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:

I_A = \frac {\pi} {2g} \int_0^{T_d} a (t)^2 dt (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]

References

  1. ^ "New predictive equations for Arias intensity from crustal earthquakes in New Zea". Journal of Seismology, Volume 13, Issue 1, pp.31-52. http://adsabs.harvard.edu/abs/2009JSeis..13...31S. Retrieved 2010-12-12. 
  2. ^ a b "7. Seismic landslide hazard zonation". Faculty of Geo-Information Science and Earth Observation of the University of Twente. 2006-09-29. http://www.itc.nl/ilwis/applications/application07.asp. Retrieved 2010-12-12. 
  3. ^ Wolfgang A. Lenhardt (2007). "Earthquake-Triggered Landslides in Austria – Dobratsch Revisited". Jahrbuch der Geologischen Bundesanstalt. http://www.geologie.ac.at/filestore/download/JB1471_193_A.pdf.