Английская Википедия:1990 South Sudan earthquakes

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Шаблон:Short description Шаблон:Infobox earthquake In 1990, present day South Sudan was rocked by a series of violent earthquakes. It started with the largest event, a Шаблон:M 7.2, and continued with multiple very large aftershocks for the next couple of months. It contains some of the largest recorded earthquakes anywhere in Africa.

Tectonic setting

The East African Rift System (EARS) is a system of rifts and associated rift lakes within the eastern portion of the African continent. It accommodates the internal breakup of Africa. It is a boundary between the Somali and African Plate. The Victoria and Rovuma microplates help accommodate additional more local stresses. The eastern portion of the rift runs from the Afar rift to Tanzania, while the western portion runs from Lake Albert (Africa) in Uganda all the way down to Mozambique.Шаблон:Sfn

The Aswa Rift Zone (ARZ) is an important geologic structure in the area near the earthquakes. The ARZ may act as a broad zone of faulting that links together the eastern and western portions of the EARS.Шаблон:Sfn The mainshock occurred along a fault where the ARZ and EARS meet.Шаблон:Sfn

Earthquake sequence

May 20 mainshock

The first and largest earthquake in the sequence struck near Juba at 02:22:01 on May 20, 1990. The event had a Шаблон:M of 6.6, with a Шаблон:M and Шаблон:M of 7.2, and struck at a depth of Шаблон:Convert.Шаблон:SfnШаблон:SfnШаблон:SfnШаблон:Sfn Its focal mechanism shows left-lateral (sinistral) strike-slip faulting, which is consistent with the shear forces in the area of the ARZ.Шаблон:Sfn The event killed 31 people and damaged some buildings in Juba, and some in Moyo, Uganda. This event is believed to be the largest earthquake ever recorded in South Sudan, and is one of the largest events known in all of Africa.[1]Шаблон:SfnШаблон:SfnШаблон:SfnШаблон:Sfn[2]

May 24 foreshock

At 19:34:44 on May 24, 1990, another large earthquake struck southern South Sudan. It occurred at a depth of Шаблон:Convert with a Шаблон:M of 6.1, Шаблон:M of 6.5-6.8 and (Шаблон:M) of 6.5-6.6.[3]Шаблон:SfnШаблон:SfnШаблон:Sfn The focal mechanism solution varies, with some showing the earthquake being the result of normal dip-slip faulting, while others suggesting it was the result of reverse dip-slip faulting instead.[4]Шаблон:Sfn

May 24 mainshock

At 20:00:08, only a little over 25 minutes after the foreshock, an even stronger earthquake struck the region: the second strongest of the whole sequence. This event was a Шаблон:M 6.6, Шаблон:M 7.0, Шаблон:M 7.1 quake that occurred at a depth of Шаблон:Convert.Шаблон:SfnШаблон:SfnШаблон:Sfn The focal mechanisms by various sources again disagree, with some showing normal faulting, with others showing strike slip faulting.Шаблон:Sfn[5][6] It caused additional structural damage to buildings previously affected by the first and strongest shock, however, no casualties occurred.[2] The worst damage was observed in uninhabited areas.[2]

July 9 mainshock

After the sequence had largely finished, another large shock struck the area for a final time. The last big earthquake in the sequence was a Шаблон:M 6.0, Шаблон:M 6.4-6.5 and Шаблон:M 6.6 event. It occurred at a depth of Шаблон:Convert.Шаблон:Sfn Focal mechanism solutions are split, with a roughly equal proportion of agencies and studies preferring a strike-slip event, with another equal proportion believing it to be a normal faulting event.[7]Шаблон:Sfn[8]

Damage

The mainshock killed 31 people and damaged buildings in Juba and Moyo, Uganda. Shaking was felt as far as Nakuru, Kenya.[2] The mainshock of May 24 did further damage. Government buildings and private institutions were damaged in Terekeka, South Sudan.[9] Older buildings in Juba reported cracked walls.[9] Between 8,000 and 10,000 of the displaced required extra relief and shelter.[9] 300,000 people were made homeless across the region as a result of the earthquakes.[10]

See also

References

Шаблон:Reflist Sources Шаблон:Refbegin

Шаблон:Refend

External links

Шаблон:Earthquakes in 1990 Шаблон:Earthquakes in Africa

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  1. ↑ Ошибка цитирования Неверный тег <ref>; для сносок usp00049hf не указан текст
  2. ↑ 2,0 2,1 2,2 2,3 Ошибка цитирования Неверный тег <ref>; для сносок NGDC не указан текст
  3. ↑ Ошибка цитирования Неверный тег <ref>; для сносок usp00049q9 не указан текст
  4. ↑ Ошибка цитирования Неверный тег <ref>; для сносок ISC-GEMquake2 не указан текст
  5. ↑ Ошибка цитирования Неверный тег <ref>; для сносок usp00049qe не указан текст
  6. ↑ Ошибка цитирования Неверный тег <ref>; для сносок ISC-GEMquake3 не указан текст
  7. ↑ Ошибка цитирования Неверный тег <ref>; для сносок usp0004bkr не указан текст
  8. ↑ Ошибка цитирования Неверный тег <ref>; для сносок ISC-GEMquake4 не указан текст
  9. ↑ 9,0 9,1 9,2 Ошибка цитирования Неверный тег <ref>; для сносок reliefweb не указан текст
  10. ↑ Ошибка цитирования Неверный тег <ref>; для сносок UPI не указан текст
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