DESERT Dead Sea Rift Transect: An interdisciplinary research project to study the Dead Sea Transform (original) (raw)

The rift-like structure and asymmetry of the Dead Sea Fault

Earth and Planetary Science Letters, 2010

Whereas the Dead Sea Fault is a major continental transform, active since ca. 13-18 Ma ago, it has a rift-like morphology along its southern part. It has been argued that this results from a transtensional component active since 5 Ma ago, due to a regional plate kinematics change. We present the results of 3D laboratory experiments carried out to test this hypothesis and to explore its consequences for the structure and morphology of the Dead Sea Fault. We conclude that a two-stage tectonic history invoking a first stage of pure strike-slip and a second stage marked by the addition of a minor transtensional component is consistent with most of the striking geological and geophysical features of the Dead Sea Fault. The structural and morphological asymmetry of the Dead Sea Fault can be explained by a transverse horizontal shear in the ductile lower crust below the transform zone. A large-scale heating event of the Arabian mantle is not required to explain these features of the Dead Sea Fault.

The Tectonic Geomorphology and the Archeoseismicity of the Dead Sea Transform in Jordan Valley

2007

The Dead Sea transform (DST) extends 1000 km from the Sinai triple junction in the south to the Tauros- Zagros collision zone in Turkey in the north. In Jordan, the DST consists of three morphotectonic elements; the Wadi Araba in the south, the Dead Sea basin in the middle and the Jordan Valley in the north. The Dead Sea is a pull- apart basin that formed due to the overlap of the Wadi Araba fault (WAF) and the Jordan Valley fault (JVF). The movement along the transform is active as indicated from both the geomorphological features and from the seismic activity. The DST is a major left lateral strike slip fault that accommodates the relative motion of the Arabian plate to the east and the Sinai plate to the west, where 107 km of cumulative left lateral offset has occurred over the last 18 million years. Based on this offset, the accumulated slip rate is estimated to be 5-10 mm/yr. Based on aerial photographic analysis of the DST and earthquake catalogue information, it is suggested ...

The crustal structure of the Dead Sea Transform

2004

To address one of the central questions of plate tectonics – How do large transform systems work and what are their typical features? – seismic investigations across the Dead Sea Transform (DST), the boundary between the African and Arabian plates in the Middle East, were conducted for the first time. A major component of these investigations was a combined reflection/refraction survey across the territories of Palestine, Israel and Jordan. The main results of this study are: (1) The seismic basement is offset by 3-5 km under the DST, (2) The DST cuts through the entire crust, broadening in the lower crust, (3) Strong lower crustal reflectors are imaged only on one side of the DST, (4) The seismic velocity sections show a steady increase in the depth of the crust-mantle transition (Moho) from ~26 km at the Mediterranean to ~39 km under the Jordan highlands, with only a small but visible, asymmetric topography of the Moho under the DST. These observations can be linked to the left-lateral movement of 105 km of the two plates in the last 17 Myr, accompanied by strong deformation within a narrow zone cutting through the entire crust. Comparing the DST and the San Andreas Fault (SAF) system, a strong asymmetry in subhorizontal lower crustal reflectors and a deep reaching deformation zone both occur around the DST and the SAF. The fact that such lower crustal reflectors and deep deformation zones are observed in such different transform systems suggests that these structures are possibly fundamental features of large transform plate boundaries.

Systematic analyses of the large-scale topography and structure across the Dead Sea Rift

Tectonics, 1997

The Dead Sea Rift (DSR) is one of the deepest continental depressions on the Earth's surface and is the best example of a continental rift lying along a transform plate boundary (the Dead Sea Transform) We systematically analyze the large-scale topography, structure, and morphology across the central part of the DSR between Lake Kinneret and the Gulf of Elat and show a distinct asymmetrical topographic pattern across the rift axis The topography analysis uses a Digital Terrain Model (DTM) of Israel and adjacent areas to plot a series of 64 profiles perpendicular to the rift axis.

Historical seismicity of the Jordan Dead Sea Transform region and seismotectonic implications

Arabian Journal of Geosciences, 2014

Based on all available files, catalogs, and previous compilations, it is found that 96 historical earthquakes (M≥6.0) were felt along the Jordan Dead Sea Transform region during the last 2,000 years. More than 50 % of these occurred in the form of sequences and swarms that lasted for different periods, some of which were volcanic related. The largest assigned magnitude is 7.6 with 667 years recurrence period, while the maximum possible future magnitude is 7.8±0.2 with 1,000± 80 years recurrence period. Quiescent periods, with a duration of up to 200 and 400 years and characterized by reduced levels of seismicity, are punctuated by active periods of tens of years when a few large earthquakes occurred. The historical seismicity indicates that all tectonic elements of the study region are presently active. Our results indicate that previous studies overestimate the level of seismicity in this region. Not less than 25 earthquakes, most of which had M≥7.0, are erroneously related to the transform. It is probable that most of these are located within the East Mediterranean region and/or along intraplate faults, rather than the Jordan Dead Sea Transform. This is evidenced by (i) frequency-magnitude results, (ii) moderatelarge East Mediterranean tsunamis, (iii) an apparent higher seismicity of the northernmost three segments compared with the southern three, (iv) relatively high annual seismic slip rate as calculated from the compiled historical seismicity, and (v) overdependence of some previous compilations on secondary rather than primary sources. The revised historical seismicity implies an annual seismic slip rate of about 0.68 cm/year, which indicates that not less than 30 % of the tectonic movements along the regional structures of the study region are aseismic. This is in agreement with results obtained from prehistoric and instrumental data.

Anatomy of the Dead Sea transform: Does it reflect continuous changes in plate motion?

Geology, 1999

A new gravity map of the southern half of the Dead Sea transform offers the first regional view of the anatomy of this plate boundary. Interpreted together with auxiliary seismic and well data, the map reveals a string of subsurface basins of widely varying size, shape, and depth along the plate boundary and relatively short (25-55 km) and discontinuous fault segments. We argue that this structure is a result of continuous small changes in relative plate motion. However, several segments must have ruptured simultaneously to produce the inferred maximum magnitude of historical earthquakes.

Detailed seismicity analysis revealing the dynamics of the southern Dead Sea area

Journal of Seismology, 2014

Within the framework of the international DESIRE (DEad Sea Integrated REsearch) project, a dense temporary local seismological network was operated in the southern Dead Sea area. During 18 recording months, 648 events were detected. Based on an already published tomography study clustering, focal mechanisms, statistics and the distribution of the microseismicity in relation to the velocity models from the tomography are analysed. The determined b value of 0.74 leads to a relatively high risk of large earthquakes compared to the moderate microseismic activity. The distribution of the seismicity indicates an asymmetric basin with a vertical strike-slip fault forming the eastern boundary of the basin, and an inclined western boundary, made up of strike-slip and normal faults. Furthermore, significant differences between the area north and south of the Bokek fault were observed. South of the Bokek fault, the western boundary is inactive while the entire seismicity occurs on the eastern boundary and below the basin-fill sediments. The largest events occurred here, and their focal mechanisms represent the northwards transform motion of the Arabian plate along the Dead Sea Transform. The vertical extension of the spatial and temporal cluster from February 2007 is interpreted as being related to the locking of the region around the Bokek fault. North of the Bokek fault similar seismic activity occurs on both boundaries most notably within the basin-fill sediments, displaying mainly small events with strike-slip mechanism and normal faulting in EW direction. Therefore, we suggest that the Bokek fault forms the border between the single transform fault and the pull-apart basin with two active border faults.