Expected ground motion in the south-east of Spain due to an earthquake in the epicentral area of the 1910 Adra earthquake
Abstract
To study the ground motion levelassociated with historical earthquakeslocated in Southern Spain, we have chosen ascenario placed in the Poniente Almeriense(Southeast Spain). In this zone, somerelevant historical earthquakes haveoccurred, such as those of 1522, 1804 and1910. In particular, the earthquakes of 1804 and 1910 the estimated and calculatedmagnitudes are of M = 6.3. Those earthquakestook place near the epicentral zone of aseismic series happened in 1993-94. As partof this series, two earthquakes with M5were recorded by strong ground motioninstruments on 23rd December 1993, and 4th January, 1994 at Adra, Almeríaand Motril. We have used the accelerationrecords as empirical Green functions inorder to simulate the expected groundmotion associated with a hypotheticalearthquake of magnitude M = 6.3 like those of1804 and 1910. The simulations have beencarried out for three sites (Almería,Adra and Motril) using three differentapproaches. A total of 30 simulations, foreach approach, have been carried out foreach ground motion component in each site.The peak ground acceleration (PGA) and theresponse spectra are compared with thevalues obtained through empiricalrelationships for the distances and soilconditions corresponding to the threechosen sites. The results of thesimulations show that the horizontal PGAcould exceed the values observed in23/XII/93 and 4/I/94 by a factor of 5-8,surpassing in some cases the value of 140gals. Besides, some of the peak spectralaccelerations simulated reach Samax =400 gals, Adra being the location where thehighest values of amax andSamax are reached, due to the nearnessof this station to the epicentres of 23/XII/93 and 4/I/94. At Almeria, the PGAvalues reach 40 gals, which may beconsidered as input in the bedrock. InMotril, the PGA surpass a value of 130gals, considering as due to a strong localsite effect. Finally, the peak groundacceleration (PGA) and the response spectraobtained with the simulations have beencompared with other values estimated through empirical relationships for similarconditions. The conclusions about theexpected ground motion levels have animportant application aimed at the revisionof the maximum acceleration and responsespectra of the Spanish building Code,NCSE-94.
- Publication:
-
Journal of Seismology
- Pub Date:
- 2003
- DOI:
- 10.1023/A:1023506015307
- Bibcode:
- 2003JSeis...7..175M