The 1954 Chlef earthquake struck Chlef Province in Algeria on September 9. Measuring 6.8 on the Richter scale, it killed 1,250 people and injured 3,000, destroying Chlef, then named Orléansville. It was followed by multiple aftershocks.
Algeria faces annual earthquakes and has undergone several changes to its earthquake building codes since its first earthquake engineering regulations from 1717.
Geology[edit]
Powerful earthquakes strike Algeria annually, ranging in Mercalli scale intensity from VI (Strong) to XI (Extreme).[2] Chlef was hit by another major earthquake in 1980 which killed 3,500 people.[3] The Atlas Mountains area faces aseismic deformation (change in shape not originating from movement of faults), with only marginal plate shifting each year.[3] Both Chlef earthquakes originated from the same reverse fault zone.[4]
The 1954 earthquake measured 6.8 on the Richter scale according to the United States Geological Survey[5] and had a depth of 9 km (5.6 mi).[6] There is evidence of crustal shortening along a NW-SE trend near the epicenter, but the structure of any faults is poorly understood.[6] Because Algeria has a thin ****f and a steep coastal slope, submarine landslides are quite common, especially during earthquakes.[7] During the 1954 earthquake, five underwater telephone cables in the Mediterranean Sea[8] were cut by an avalanche, three recording the exact time of impact.[7]
Damage and casualties[edit]
The earthquake hit Chlef Province[5] at 2:17 AM local time, lasting 12 seconds.[9] The initial death toll was set at 396 then raised to about 800,[9] but this was revised to 1,250 people. The earthquake injured 3,000 and devastated the province. Some victims were buried while in bed.[10]
Shaking extended west to Mostaganem, south to Tiaret, and east to Tizi Ouzou, and many aftershocks followed the earthquake, including a major tremor at 22:18 UTC on September 16 which further damaged Orleansville.[8] The main shock ruptured 16 km (9.9 mi) of rock, ripping faults and creating visible fissures in the ground along the Dahra Massif. Survivors described a sensation of rotating along an axis and that the rubble reminded them of "bombed cities in Europe."[9]
The United States Geological Survey lists the 1954 quake among the deadliest earthquakes in history.[5] Agence France-Presse (AFP) reported that it was the worst earthquake in North African history.[9]
Aftermath[edit]
Orléansville was devastated by the earthquake; a fifth of it wholly destroyed,[10] it was rebuilt and renamed El Asnam and later Chlef.[8]
While Algeria had set earthquake resistance regulations as early as 1717, it was the 1954 earthquake that ushered in fully comprehensive reforms for seismic-resistant design.[2]