Detection of the seismic quiescence along the seismic active faults in Kalabsha area, west of Lake Nasser, Aswan, Egypt

Hassib, Gaber H.; Hamed, H; Dahy, Sayed A.; Hassoup, Awad; Moustafa, Sayed S. R.

doi:10.1556/ageod.45.2010.2.6

Cited by 8 publications

(6 citation statements)

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“…According to Simpson et al [1990] and Kebeasy and Gharib [1991], except the main shock and most of the immediate aftershocks, which occurred beneath Gebel Marawa at depths between 15 and 30 km, all other earthquakes occurred between 0 and 12 km (Figure 1). Deep seismicity followed the typical aftershock pattern and died down with time while the shallow seismicity still continues (Figure 2) [ Hassib et al , 2010]. Kebeasy and Gharib [1991] and Abou Elenean [2003] suggested that most of the seismicity in the Aswan area is concentrated along the identified fault segments.…”

Section: Geology Tectonics and Seismicity Of The Areamentioning

confidence: 99%

“…All the earthquakes of this swarm with a magnitude greater than 2.5 occurred on 19 June 1987 and hence, we chose to perform our calculations on the epoch of 19 June 1987 at a depth of 8 km. CFPS of this swarm is predominantly of strike‐slip type [ Hassib et al , 2010]. The second swarm from 12 to 14 April 2007 occurred at almost the same place as that of the first swarm.…”

Section: Analysis Of the Effect Of Aswan Reservoir Impoundment On Thementioning

confidence: 99%

“…There were 15 events of M ≥ 3.0 and two events with M ≥ 4.0. CFPS of this swarm is derived as predominantly strike‐slip type with a small normal slip component [ Hassib et al , 2010]. Temporal variation in the pore pressure since the impoundment till 2009, at 8 km depth and at the hypocenter of these two swarms, is shown in Figure 4a.…”

Section: Analysis Of the Effect Of Aswan Reservoir Impoundment On Thementioning

confidence: 99%

“…In zone E, around 125 earthquakes of magnitude 1.3 to 4.1 occurred from August to December 2004 including 15 earthquakes in the range M 3.0–3.7 and one earthquake of M 4.1 (Figure 6e). Hassib et al [2010] derived a strike‐slip type focal mechanism for this swarm, which we adopt in our calculations for zones D and E. Since there is an ambiguity whether these earthquakes occurred on the E‐W or N‐S trending faults, we analyzed the effect of reservoir impoundment on both the planes (Figures 8b and 8c). Results are not significantly different from one nodal plane to the other.…”

Section: Analysis Of the Effect Of Aswan Reservoir Impoundment On Thementioning

confidence: 99%

“…In zone E, around 125 earthquakes of magnitude 1.3 to 4.1 occurred from August to December 2004 including 15 earthquakes in the range M 3.0-3.7 and one earthquake of M 4.1 (Figure 6e). Hassib et al [2010] derived a strikeslip type focal mechanism for this swarm, which we adopt in Figure 3b), and at 20 km, corresponding to the hypocenter of the 14 November 1981 earthquake, for the entire period of reservoir operation. Blowups of water-level and pore pressure changes are shown in Figure 4b for the 2007 swarm and in Figure 4c for the 1981 main shock.…”

Section: Analysis For Zones D and Ementioning

confidence: 99%

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Role of fluids in the earthquake occurrence around Aswan reservoir, Egypt

Gahalaut

Hassoup

2012

J. Geophys. Res.

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.[1] Continuing seismicity for about 30 years near a large western embayment of the Lake Nasser, about 50 km from the Aswan High Dam in Egypt, has led to a debate about the possibility of its relation with the reservoir impoundment. The largest event in the region occurred on 14 November 1981 (M 5.3), 20 km beneath the Wadi Kalabsha embayment, a westward extension of the Lake Aswan. Since then, continuous monitoring of seismic activity has given an excellent opportunity to study the spatiotemporal distribution of seismicity in the area. Most of the immediate aftershocks of the 1981 main shock were located in the Gebel Marawa area at depths between 15 and 30 km. Depths of almost all earthquakes away from this zone were shallower than 12 km. To quantify the effect of the reservoir impoundment on the seismicity of the Aswan area, we calculated changes in stress and pore pressure due to the reservoir impoundment using Green's function approach. The change in Coulomb stress (DS) is calculated on the fault planes responsible for majority of the seismicity of the region. We found that for all the seismogenic faults, DS is negative, i.e., stabilizing, when we consider the effect of the reservoir load only, whereas it is positive, i.e., destabilizing, when we include pore pressure. For example, at the hypocenter of the main earthquake, shear stress, normal stress, and pore pressure due to reservoir operation are estimated as 5.5, 13.2, and 13.5 kPa, respectively, which suggest that DS is À3.1 kPa when we do not consider the effect of pore pressure and 5.7 kPa when contribution from pore pressure is considered. Hence, the seismicity in the Aswan lake region is driven by the pore pressure due to reservoir impoundment.

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Section: Geology Tectonics and Seismicity Of The Areamentioning

confidence: 99%

Section: Analysis Of the Effect Of Aswan Reservoir Impoundment On Thementioning

confidence: 99%

Section: Analysis Of the Effect Of Aswan Reservoir Impoundment On Thementioning

confidence: 99%

Section: Analysis Of the Effect Of Aswan Reservoir Impoundment On Thementioning

confidence: 99%

Section: Analysis For Zones D and Ementioning

confidence: 99%

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