Three-dimensional structure of Conrad and Moho discontinuities in Egypt

Abdelwahed, Mohamed F.; Khrepy, Sami El; Qaddah, Atef

doi:10.1016/j.jafrearsci.2013.04.007

Cited by 22 publications

(14 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Conrad discontinuity is at about 18-20 km depth, and the Moho discontinuity is at 27-30 km depth. The 3D structure of Conrad and Moho discontinuities based on seismic data recorded recently at the vicinity of the Abu Dabbab area (Abdelwahed et al, 2013) provides similar estimates: 15 km depth for the Conrad discontinuity and 27-31 km for Moho. The discrepancy between these models is due to strong variations of the crustal structures and slightly different locations of the studied areas.…”

Section: Introductionsupporting

confidence: 58%

Crustal Structure in the Area of the Cannon Earthquakes of Abu Dabbab (Northern Red Sea, Egypt), from Seismic Tomography Inversion

Khrepy

Koulakov

Al‐Arifi

2015

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

Abu Dabbab seismogenic zone is located close to the Egyptian Red Sea coast. It is characterized by cannon earthquakes, long continued seismic activity, and frequent earthquake swarms. Earthquakes in this zone have occurred with high frequency over a long period of time in a confined linear zone that extends offshore in the Red Sea. A unique property is that earthquake signals can be heard by humans. Most previous studies suggested a magmatic origin for this activity. We perform a detailed earthquake tomography to image the crustal structure beneath Abu Dabbab and to explore the origin of its seismic activity and the cannon earthquakes. Based on the local and regional data, we construct a large-scale seismic tomography model for the entire region and then enhance it for the local area of Abu Dabbab. We find the seismicity forms an arc-shaped cluster that surrounds an aseismic block of high velocities and a low V P =V S ratio. According to the tomography results, we developed a new schematic geodynamic model proposing that the confined linear seismic zone in Abu Dabbab is due to the location of an active fault below a large, rigid, nondeformed block of Precambrian igneous rock, which reaches a depth of ∼10 km. The surface between this block and the moving parts of the fault are lubricated by fluids penetrating into the crust from the Red Sea as a result of combined strike-slip and thrust displacements along the faults. These results reveal strong arguments for the tectonic origin of the seismicity associated with an important role of the fluid contents in Abu Dabbab area.

show abstract

Section: Introductionsupporting

confidence: 58%

Crustal Structure in the Area of the Cannon Earthquakes of Abu Dabbab (Northern Red Sea, Egypt), from Seismic Tomography Inversion

Khrepy

Koulakov

Al‐Arifi

2015

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

show abstract

“…References consulted for Eastern Africa‐MER‐Afar system: Hayward and Ebinger (), Ebinger (), Kendall et al (), Wright et al (), Rowland et al (), Corti (), Agostini et al (), and Muirhead et al (). References consulted for Gulf of Suez‐Red Sea System: Angelier (), Cochran and Martinez (), Badawy and Horváth (), Bosworth and McClay (), Cochran (), Wolfenden et al (), Avni et al (), and Abdelwahed et al (). For references on other rifts, see main text.…”

Section: Discussionmentioning

confidence: 99%

Rapid Evolution of Subduction‐Related Continental Intraarc Rifts: The Taupo Rift, New Zealand

et al. 2017

View full text Add to dashboard Cite

The evolution of the continental intraarc Taupo Rift in the North Island, New Zealand, is rapid, significantly faster than comparative intracontinental rifts such as the African Rifts. Based on our faulting data and published geological, geophysical, and borehole data, we show that activity in the ~2 Ma Taupo Rift has rapidly and asymmetrically narrowed via inward and eastward migration of faulting (at rates of approximately 30 km Myr−1 and 15 km Myr−1, respectively) and has propagated southward along its axis ~70 km in 350 kyr. The loci of voluminous volcanic eruptions and active faulting are correlated in time and space, suggesting that a controlling factor in the rapid rift narrowing is the presence of large shallow heterogeneities in the crust, such as large rhyolitic magma bodies generated by subduction processes, which weaken the crust and localize deformation. Eastward migration of faulting also follows the eastward migration of the volcanic arc which may be related to rollback of the Pacific crust slab at the Hikurangi subduction zone. Southward propagation of the rift is linked with southward migration of the Hikurangi Plateau/Chatham Rise subduction point and occurs episodically aided by stress changes associated with voluminous local volcanism. The large magma supply during early continental intraarc rift stages explains faster evolution (from tectonic to magmatic) than intracontinental rifts. However, the fast changes in magma supply from the subduction zone can also lead to evolution reversals (more evolved magmatic stages reverting to less evolved tectonic stages), rift cessation, and thus failed continental breakup.

show abstract

“…With respect to recent results, we refer to Abdelwahed et al (2013), showing the Conrad and Moho discontinuities of eastern Egypt and the Red Sea. Corchete et al (2017) determined the crustal and uppermost mantle structure in northeastern Egypt based on Rayleigh wave analysis.…”

Section: Introductionmentioning

confidence: 92%

“…Such an integrative geophysical study is applied to the study area for the first time; this was made possible due to the availability of new data after establishing in 1997 the Egyptian National Seismic Network (ENSN), which provided the input for new receiver functions and tomography models of the Egyptian lithosphere (e.g., El Khrepy et al, , 2016Abdelwahed et al, 2013;Hosny and Nyblade 2016;Mohamed et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Density structure and isostasy of the lithosphere in Egypt and their relation to seismicity

2018

View full text Add to dashboard Cite

Abstract. A joint analysis of the new satellite-terrestrial gravity field model with recent data on the crustal structure and seismic tomography was conducted to create an integrative model of the crust and upper mantle and to investigate the relation of the density structure and the isostatic state of the lithosphere to the seismicity of Egypt. We identified the distinct fragmentation of the lithosphere of Egypt in several blocks. This division is closely related to the seismicity patterns in this region. The relatively dense and strong lithosphere in the Nile Delta limits the seismic activity within this area, while earthquakes are mainly associated with the boundaries of this block. In the same way, the relatively strong lithosphere in the Isthmus of Suez and northern Mediterranean prevents the Gulf of Suez from opening further. The central part of Egypt is generally characterized by an increased density of the mantle, which extends to the Mediterranean at a depth of 100 km. This anomaly deepens southward to Gilf Kebir and eastward to the Eastern Desert. The average density of the crystalline crust is generally reduced in this zone, indicating the increased thickness of the upper crust. The low-density anomaly under the northern Red Sea is limited to 100-125 km, confirming the passive origin of the extension. Most of the earthquakes occur in the crust and uppermost mantle in this structure due to the hot and weak upper mantle underneath. Furthermore, an asymmetric lithosphere structure is observed across the northern Red Sea. The isostatic anomalies show the fragmentation of the crust of Sinai with the high-density central block. Strong variations in the isostatic anomalies are correlated with the high level of seismicity around Sinai. This tendency is also evident in the northern Red Sea, east of the Nile Valley, and in parts of the Western Desert.

show abstract

Three-dimensional structure of Conrad and Moho discontinuities in Egypt

Cited by 22 publications

References 40 publications

Crustal Structure in the Area of the Cannon Earthquakes of Abu Dabbab (Northern Red Sea, Egypt), from Seismic Tomography Inversion

Crustal Structure in the Area of the Cannon Earthquakes of Abu Dabbab (Northern Red Sea, Egypt), from Seismic Tomography Inversion

Rapid Evolution of Subduction‐Related Continental Intraarc Rifts: The Taupo Rift, New Zealand

Density structure and isostasy of the lithosphere in Egypt and their relation to seismicity

Contact Info

Product

Resources

About