A study of crustal deformation along the Red Sea region using geodetic and seismic data from Egypt and Yemen (original) (raw)
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EVALUATION OF THE CRUSTAL DEFORMATION IN THE GULF OF SUEZ REGION USING GPS TECHNIQUES
Recently, one of the important methods for studying crustal deformation, by means of space techniques, is the Global Positioning System (GPS). The earth's crust deformation attains values of only few mm/yr and can be determined according to the spatial and time density of the measurements as well as their degree of accuracy. A geodetic network consists of 11points was established early in 1997 in southern Sinai . This network was observed six times in different campaigns during the period 1997 – 2003. The observed data were analyzed using Bernes 4.2 software to determine velocity vectors along the Gulf of Suez and Sinai Peninsula. The estimated horizontal velocity vectors in the International Terrestrial Reference Frame (ITRF2000) show that the velocity of Sinai Peninsula ranges from 1.8 to 2.3± 0.5 mm/yr in the NE direction. This velocity is consistent with those predicted by the model NUVEL- 1A in the same direction but smaller in magnitude. The strain Tensor program was used to estimate the principal axes of strains. The principal axes of the strain indicate that the studied region is mainly divided into two areas: western part, around Gulf of Suez, where extensional strain is predominant and the eastern part, around the Gulf of Aqaba, where compressional strains prevail. Principal axes of the strain indicate that an extensional force is acting along the Gulf of Suez in NE-SW direction. Moreover, the principal axes of strains show a good correlation with the directions obtained from earthquake focal mechanisms.
Crustal deformation of the southeastern corner of Egypt derived from geodetic data
NRIAG Journal of Astronomy and Geophysics
The proper evaluation of the crustal deformation is important prior to any strategic projects. Due to the importance of the southeastern corner of Egypt which contains many mineral resources beside a lot of attractive tourism places, we have selected this area to estimate the recent crustal movements and its relation to earthquake activities within this region using the available GPS and seismicity measurements. We used 19 permanent and campaign GPS sites in and around the study area that cover the time span 2007-2014. Most of these sites are related to Abu-Dabbab and Lake Nasser networks. The obtained GPS results show that there is an observed deformation in Abu-Dabbab area, along Red Sea coast, which characterized by a seismic cluster. The localization of the observed movements at Abu-Dabbab area may indicate that the deformation is related to a local structure within the study area. On the other hand, GPS sites located East of Lake Nasser and the permanent GPS sites in southern Egypt do not show any significant velocity field and it seems to be stable compared to Abu-Dabbab region. Even with the non-uniform spatial resolution of the GPS sites used in this work, our results are in good agreement with the seismicity of the study area.
Geophysical Journal International, 2010
New Global Positioning System (GPS) measurements in NW Syria provide the first direct observations of near-field deformation associated with the northern Dead Sea fault system (DSFS) and demonstrate that the kinematics of the northern section of this transform plate boundary between the Arabian and Sinai plates deviate significantly from plate model predictions. Velocity estimates based on GPS survey campaigns in 2000, 2007 and 2008, demonstrate left-lateral shear along the northern DSFS with 1σ uncertainties less than 0.7 mm yr−1. These velocities are consistent with an elastic dislocation model with a slip rate of 1.8–3.3 mm yr−1 and a locking depth of 5–16 km. This geodetically determined slip rate is about half of that reported farther south along the central section (Lebanese restraining bend) and the southern section (Jordan Valley and Wadi Araba) of the transform and consequently requires some deformation to occur away from the transform along other geological structures. The factor of two difference in slip rates along the transform is also consistent with differing estimates of total fault slip that have occurred since the mid Miocene: 20–25 km along the northern DSFS (in NW Syria) versus about 45 km along the southern DSFS segment. Some of the strain deficit may be accommodated by north–south shortening within the southwestern segment of the Palmyride fold belt of central Syria. Additionally, a distinct change in velocity occurs within the Sinai plate itself. These new GPS measurements, when viewed alongside the palaeoseismic record and the modest level of present-day seismicity, suggest that the reported estimates of recurrence time of large earthquakes (M > 7) along the northern section of the DSFS may be underestimated owing to temporal clustering of such large historical earthquakes. Hence, a revised estimate of the earthquake hazard may be needed for NW Syria.
GPS-derived velocity and crustal strain field in the Suez-Sinai Area, Egypt
Bull. Earthq. Res. Inst. Univ. Tokyo, 2005
Five GPS measurements collected in campaign mode during the period +331῍,**, are analyzed to derive velocity vectors and principal components of crustal strains along the Gulf of Suez and in the southern part of the Sinai Peninsula, Egypt. Estimated horizontal velocity vectors in ITRF,*** are found to be in the range of ,3῍-/ mm/yr with an uncertainty level in the order of +῍, mm/yr (3/ῌ confidence level). Then, estimated velocities are converted into a kinematic reference frame (Prawirodirdjo and Bock, ,**.) to discuss crustal deformation relative to the Eurasian plate. Least-Squares prediction (LSP) technique is employed to segregate signal and noise from velocity vectors. Estimated signals are used to reconstruct strains, dilatations, maximum shear strains, and principal axes of strains. Strains obtained might portray active tectonic environments in the region under study. (+) Dilatational strains indicate that the region under study is mainly divided into two areas : the western part around the Gulf of Suez where extensional strain is predominant, and the eastern part around the Gulf of Aqaba where compressional strains prevail. (,) Maximum shear strain is mostly accommodated at the Gulf of Suez and Gulf of Aqaba. Distribution of seismicity shows high consistency with high shear strain areas. The estimated dilatation strain rate and the maximum shear strain rate are both *.,/ Micro-strain/yr on average. (-) Principal axes of the strains indicate that an extensional force is acting along the Gulf of Suez in the NE-SW direction. Moreover, the principal axes of strains show a good correlation with the SHmax directions obtained from earthquake focal mechanisms and borehole breakouts.
Deformation analysis of Great Cairo deduced from potential and GPS data, Egypt.
NRIAG Journal of Geophysics, 651-680., 2009
Detecting crustal movements using the Global positioning system (GPS) has been applied at different seismically active areas in all the world. Egypt is recognized as a moderate earthquake activity region with frequent moderate events. Most of its seismicity is concentrated at its northern part and around greater Cairo. For instance, there have been earthquake activities in the southwest of Cairo region (Dahshour area) since 1847. In order to monitor crustal deformation around this active area, a local geodetic network consists of 8 geodetic points were established in the year 2004, around the active faults. Three campaigns were performed and processed using Bernese GPS software version 5.0. The aim of the present study is to determine the tectonic elements presented and to throw lights upon the geodynamic regime of the study area. The velocity vectors for each epoch of observations were calculated and deformation analysis was performed. The horizontal velocity varies in average between 1 and 8 mm per year across the network.
Kinematics and deformation of the southern Red Sea region from GPS observations
Geophysical Journal International
Summary The present-day tectonics of the southern Red Sea region is complicated by the presence of the overlapping Afar and southern Red Sea rifts as well as the uncertain kinematics and extent of the Danakil block in between. Here we combine up to 16 years of GPS observations and show that the coherent rotation of the Danakil block is well described by a Danakil-Nubia Euler pole at 16.36○N, 39.96○E with a rotation rate of 2.83 ○/My. The kinematic block modeling also indicates that the Danakil block is significantly smaller than previously suggested, extending only to Hanish-Zukur Islands (∼13.8○N) with the area to the south of the islands being a part of the Arabian plate. In addition, the GPS velocity field reveals a wide inter-rifting deformation zone across the northern Danakil-Afar rift with ∼5.6 mm/yr of east-west opening across Gulf of Zula in Eritrea. Together the results redefine some of the plate boundaries in the region and show how the extension in the southern Red Sea g...
The Nile Valley in Egypt is located to the west of the Red Sea Rift and to the south of the Mediterranean Sea. Recently, some moderate earthquakes were occurred along the Nile Valley at the eastern and western side. Tectonically, the Nile Valley is controlled by NW–SE, NE–SW, E–W and N–S tectonic trends due to the exerted forces and stresses. A program of studying the recent crustal movements in Egypt has been started since 1984 to cover some areas which are characterized by the occurrence of felt Earthquakes. One of these areas is the Nile Valley. About 6 moderate earthquakes with magnitudes more than 4 were occurred on both sides of River Nile. The present study aimed to determine the recent crustal movement parameters along the Nile Valley using the Global Positioning System (GPS) measurements. To achieve this mission, a GPS network consisting of ten geodetic stations has been established on both sides along the Nile Valley area. GPS measurements have been collected from 2007 to 2012. The collected data were processed using Bernese 5.0 Software. The result of the data analysis indicates that the rate of local velocity is small ranging from 1 to 4 mm/year. This rate is consistent with the low rate of occurrence of recent earthquakes activity along the Nile Valley area. But, the results obtained from the calculation of the regional velocity indicated that the velocity of the GPS stations including the African Plate motion is about 25 mm/year in the northeast direction which is consistent with the African Plate motion direction.
NRIAG Journal of Astronomy and Geophysics, 2016
The northern part of Egypt is a rapidly growing development accompanied by the increased levels of standard living particularly in its urban areas. From tectonic and seismic point of views, the northern part of Egypt is one of the interested regions. It shows an active geologic structure attributed to the tectonic movements of the African and Eurasian plates from one side and the Arabian plate from the other side. From historical point of view and recent instrumental records, the northern part of Egypt is one of the seismo-active regions in Egypt. The investigations of the seismic events and their interpretations had led to evaluate the seismic hazard for disaster mitigation, for the safety of the densely populated regions and the vital projects. In addition to the monitoring of the seismic events, the most powerful technique of Global Navigation Satellite System (GNSS) will be used in determining crustal deformation where a geodetic network covers the northern part of Egypt. Joining the GPS Permanent stations of the northern part of Egypt with the Southern part of Europe will give a clear picture about the recent crustal deformation and the African plate velocity. The results from the data sets are compared and combined in order to determine the main characteristics of the deformation and hazard estimation for specified regions. Final compiled output from the seismological and geodetic analysis will throw lights upon the geodynamical regime of these seismo-active regions. This work will throw lights upon the geodynamical regime and to delineate the crustal stress and strain fields in the study region. This also enables to evaluate the active tectonics