The National Seismic Network monitored light earthquakes on Sunday morning, about 10 km southeast of Mahalla al-Kubra, with a magnitude of 3.5 on the Richter scale, Latitude 30.39° N, Longitude E 31.25° East, and at a depth of 21 km.
The National Seismic Network Station of the National Institute for Astronomical Research recorded an earthquake today, Thursday, November 19, 2020, east of Cairo, 13 km southeast of the Administrative Capital.
Where this tremor occurred this morning and was not felt by any of the citizens, and it was 3.0 degrees on the Richter scale at 29.91 north latitude and 31.84 east longitude.
Dr. Gad Al-Qadi, head of the National Institute for Astronomical Research, had made it clear in a special statement to “Echo of the Country” that the sky of Cairo will witness this evening a new astronomical phenomenon.
Al-Qadi explained that the moon will be associated with the two large planets (Jupiter and Saturn), indicating that this scene can be seen when the night comes until eight in the evening, when it can be viewed with the naked eye or through amateur telescopes
Similarly, on 12 October 1992, an earthquake, magnitude mb = 5.9 and M s = 5.2, hit the City of Cairo, Egypt. It was this century’s largest earthquake in northern Egypt with related destruction in the City of Cairo, the Nile Valley and the Nile Delta areas. Our source parameter determinations show that the 1992 earthquake had a normal faulting mechanism, seismic moment M o = 5.2 × 1017 Nm, centroid depth of 23 km and a source time function duration of 3 seconds. The mechanism is compared with those corresponding to two other events that occurred in the northern Red Sea.
The similarity between the mechanisms as well as the spatial distribution of the geological faults around Cairo suggest seismic activity along the extension of the stress field of the Red Sea rift system to the area around the City of Cairo. This situation affects the level of seismic hazard in the Cairo area.
The 1992 earthquake belongs to an unusual class of relatively small, M w > 6.0, yet destructive earthquakes. The damage caused by these events is usually attributed to their shallow focal depth, 5 km, and to amplification of seismic waves in the local soil beneath the damaged structures. However, the Cairo earthquake deviates from other events of this class since the focal depth was determined to be 23 km.
We calculated synthetic accelerograms for the 1992 earthquake with the loose sediments observed in the Nile Valley, and show that this enhanced the amplitude of the acceleration by a factor of two. However, the determined accelerations, about 0.5 m s-2, cannot alone explain the relatively large amount of damaged structures. Hence, a major cause to the destruction is likely the poor state of construction of the Cairo buildings.
