Attenuation of Intensity for the Zemmouri Earthquake of 21 May 2003 (Mw 6.8): Insights for the Seismic Hazard and Historical Earthquake Sources in Northern Algeria - Historical Seismology: Interdisciplinary Studies of Past and Recent Earthquakes - page 325

(C)

0

-2

-4

-6

-8

Distance

1 10 100 1000

(D)

F it attenuation in the azimuth parallel to the fault
I = I 0 +1.22-0.01*D-1.820 log(D)

0

azimuth using isoseismals:
Coef of determination = 0.93

-2

-4

it attenuation in the azimuth perpendicular
to the fault azimuth using isoseismals:

F
I=I +0.159-0.004 *D-2.325 log(D)

-6

0

Coef of determination = 0.88

-8

Distance 1 10 100 1000

Fig. 4 (continued)

horizontal peak acceleration decays as a function of distance (Laouami et al. 2004)
and provide a comparison with the attenuation of intensities for the Algiers region.
Only the PGA values at sites for which the intensity is available are considered and
we obtain a good correlation between the distance and PGA parameters (Fig. 4f).
All observed PGA values show a better fit than the average values predicted by