1994 Mascara earthquake

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1994 Mascara earthquake
1994 Mascara earthquake is located in Algeria
1994 Mascara earthquake
UTC time1994-08-18 01:13:05
ISC event160696
USGS-ANSSComCat
Local dateAugust 18, 1994 (1994-08-18)
Local time02:13 a.m. WAT
Magnitude5.9 Mw[1]
5.6 ML 
Depth8.7 km (5.4 mi)
Epicenter35°31′12″N 0°06′22″W / 35.520°N 0.106°W / 35.520; -0.106Coordinates: 35°31′12″N 0°06′22″W / 35.520°N 0.106°W / 35.520; -0.106
TypeOblique–reverse
Areas affectedAlgeria
Max. intensityVII (Very strong)
VIII (Damaging)
Casualties171 dead and 289 injured.

The 1994 Mascara earthquake occurred on August 18 at 02:13 local time with an epicenter in the Tell Atlas. Despite the moderate size of the earthquake, measuring 5.9 on the moment magnitude scale,[1] and 5.6 on the local magnitude scale, it caused the deaths of 171 people and left 8,000 to 10,000 homeless.[2] Reaching a maximum intensity of VIII (Damaging) on the MSK 64 scale, the earthquake was far more devastating for its size, destroying or damaging many homes.[3]

Tectonic setting[]

See also: Geology of Algeria, Geography of Algeria, and Atlas Mountains

The People's Democratic Republic of Algeria located in Northwest Africa is situated near a complex and poorly defined convergent plate boundary which separates the African Plate from the Eurasian Plate.[4] The converging plates create a zone of compression in northern Algeria, which are accommodated by mainly thrust and reverse faults onshore and inland. Thrusting of strata due to compression results in the formation of the Atlas Mountains in Algeria and Morocco. The tectonic situation of Algeria also make the country vulnerable to large and deadly seismic events with magnitudes greater than 6.0. The offshore thrust faults also pose a tsunami threat to the Algerian coast during large earthquakes.[5]

Earthquake[]

The earthquake occurred as a result of oblique–reverse faulting.[6] The focal mechanism calculated by the European-Mediterranean Seismological Centre suggest strike-slip and reverse components during the earthquake. Based on the epicenter location and depth of the earthquake, the event is inferred to have occurred at the junction of two reverse faults, with either one of them rupturing and producing the quake. The first fault is an east–west striking structure identified as an old reverse structure that is now an active dextral-slip fault. The other fault has a northeast-southwest strike and with a reverse slip sense.[7]

Characteristics[]

No surface ruptures were observed during a field survey after the earthquake, however, cliff failures and rockfalls were found.[8]

Impact[]

See also: Earthquake engineering and Unreinforced masonry building

On August 19, 1994, the New York Times reported that at least 150 people had been killed, 300 injured and between 8,000 and 10,000 were left homeless. It was reported that the worst damage inflicted by the earthquake was in the rural villages where many mud-constructed homes had collapsed, killing or injuring individuals who were residing in them.[9]

Because the earthquake occurred in the early morning, many residents were killed in their sleep due to collapsing homes. Most of the individuals killed were caught off-guard after being awaken and buried under rubble from their collapsing homes.[9] The remaining frightened survivors decided to spend the rest of the morning in the streets for fear than further aftershocks may collapse their already damaged dwellings.[7]

Eventually, a report released in November 1994 revised the death toll to 171, with a further 645 injured, 286 in critical condition. In just 12 seconds, the Mw  5.9 earthquake caused tremendous damage in the rural towns and villages, making 10,000 to 12,500 people from over 1,300 families homeless.[10] A total of 2,000 houses and ten schools were seriously affected or collapsed. [7]

The village of Shadlia alone accounted for 105 of the 171 fatalities in the earthquake. Also in this village, along with Hacine and Sidi Ali Cherif, the earthquake completely wiped out all homes and public structures. The village of Wilaya lost at least 50% of all buildings due to the tremor. A large number of farming facilities are also destroyed or damaged. In Hacine village, a pertol station and town hall building was undamaged, however, aging structures and ten schools built on small support columns suffered cracks or severe damage.[7]

In the city of Oran in Oran Province, located 75 km northwest of the earthquake, the shock was felt strong enough to cause some cracks in buildings. Based on the evaluation of damage to structures and they type of structures that were damaged, the maximum intensity of this earthquake was assigned VIII on the Medvedev–Sponheuer–Karnik scale.[7]

See also[]

References[]

  1. ^ Jump up to: a b "M 5.9 - northern Algeria". USGS-ANSS. USGS. Retrieved 1 April 2021.
  2. ^ "Significant Earthquake Information ALGERIA: MASCARA". NGDC NCEI. NGDC NCEI. Retrieved 1 April 2021.
  3. ^ D. Benouar; A. Aoudia; S. Maouche; M. Meghraoui (November 1994). "The 18 August 1994 Mascara (Algeria) earthquake—a quick‐look report". Terra Nova. 6 (6): 634–638. doi:10.1111/j.1365-3121.1994.tb00529.x.
  4. ^ A. Leprêtre, F. Klingelhoefer, D. Graindorge, P. Schnurle, M. O. Beslier, K. Yelles, J. Déverchère, R. Bracene (2013). "Multiphased tectonic evolution of the Central Algerian margin from combined wide-angle and reflection seismic data off Tipaza, Algeria". Geophysical Research Letters: Solid Earth. 118 (8): 3899–3916. doi:10.1002/jgrb.50318. Retrieved 19 July 2021.CS1 maint: multiple names: authors list (link)
  5. ^ Abdelkarim Yelles-Chaouche; Abdelaziz Kherroubi (2017). Hamoud Beldjoudi (ed.). "The large Algerian earthquakes (267 A.D.-2017)". Física de la tierra. Universidad Complutense de Madrid. 29. doi:10.5209/FITE.57617. ISSN 1988-2440. Retrieved 19 July 2021.
  6. ^ Ayadi, A.; Ousadou-Ayadi, F.; Bourouis, S.; Benhallou, H. (2002). "Seismotectonics and seismic quietness of the Oranie region (Western Algeria): The Mascara earthquake of August 18th 1994, Mw = 5.7, Ms = 6.0". Journal of Seismology. 6: 13–23. doi:10.1023/A:1014276727136.CS1 maint: multiple names: authors list (link)
  7. ^ Jump up to: a b c d e A. Ayadi, F. Ousadou-Ayadi, S. Bourouis & H. Benhallou (2002). "Seismotectonics and seismic quietness of the Oranie region (Western Algeria): The Mascara earthquake of August 18th 1994, Mw = 5.7, Ms = 6.0". Journal of Seismology. 6 (1): 13-23. doi:10.1023/A:1014276727136.CS1 maint: multiple names: authors list (link)
  8. ^ Djillali Benouar; Abdelkrim Aoudia; Said Maouche; Mustapha Meghraoui (1994). "The 18 August 1994 Mascara (Algeria) earthquake—a quick-look report". Terra Nova. 6 (6): 634–638. doi:10.1111/j.1365-3121.1994.tb00529.x.
  9. ^ Jump up to: a b The Associated Press (19 August 1994). "Earthquake Strikes Rural Algeria, Killing 150". The New York Times. Retrieved 19 July 2021.
  10. ^ "Algeria: Earthquake - Aug 1994". Relief Web. Relief Web. Retrieved 1 April 2021.
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