The Jordan Rift Valley was formed many millions of years ago in the Miocene epoch (23.8 – 5.3 Myr ago) when the Arabian Plate moved northward and then eastward away from Africa. One million years later, the land between the Mediterranean and the Jordan Rift Valley rose so that the sea water stopped flooding the area.
The geological and environmental evolution of the valley since its inception in the Oligocene can be seen in a variety of sedimentary and magmatic rock units, preserved as continuous sequences in the deeper basins. The outcropping formations around the basins represent alternating deposition and erosion phases.[1]
The lowest point in the Jordan Rift Valley is in the Dead Sea, the lowest spot of which is 790 m (2,590 ft) below sea level. The shore of the Dead Sea is the lowest land on earth, at 400 m (1,300 ft) below sea level. Rising sharply to almost 1,000 m (3,300 ft) in the west, and similarly in the east, the rift is a significant topographic feature over which a few narrow paved roads and difficult mountain tracks lead.[2] The valley north of the Dead Sea has long been a site of agriculture because of water available from the Jordan River and numerous springs located on the valley's flanks.
The DST fault system is generally considered to be a transform fault that has accommodated a 105-kilometre (65 mi) northwards displacement of the Arabian Plate.[4][5] This interpretation is based on observation of offset markers, such as river terraces, gullies and archaeological features, giving horizontal slip rates of several mm per year over the last few million years.[6]GPS data give similar rates of present-day movement of the Arabian Plate relative to the Africa Plate.[7] It has also been proposed that the fault zone is a rift system that is an incipient oceanic spreading center, the northern extension of the Red Sea Rift.[8]
In 1033, the rift valley was struck by a magnitude 7.3 earthquake, believed to have been produced along the DST fault system.[9] It caused widespread destruction, a tsunami, and killed 70,000 people.[10]
Future threat
View of the Jordan Valley, where the earthquake occurred.
The 1033 AD event was the last large earthquake on the Jordan Valley Fault. Given the estimated slip rate is 4.9 ± 0.2 mm (0.1929 ± 0.0079 in) per year, approximately 5 m (16 ft) of potential slip has been accumulated. An estimated 3.5–5 m (11–16 ft) of slip could be produced during a future earthquake along a 110 km (68 mi) × 20 km (12 mi) fault area. Such an event would suggest an earthquake of Mw 7.4, posing a great seismic threat to the region.[11]
In late 2020, researchers at Tel Aviv University said that an earthquake of magnitude 6.5 is expected to occur in the area, resulting in many fatalities. Researchers also stated that the frequency of large earthquakes in the region is significantly underestimated.[12] Previous studies suggested a recurrence interval of 10,000 years for magnitude 7.5 earthquakes, but the researchers said the figure was 1,300 to 1,400 years.[13]Yosef Shapira, the then State Comptroller of Israel, said that a major earthquake in Israel could kill up to 7,000 people if safety recommendations are not enforced. Reports of the years 2001, 2004 and 2011 found that the Israeli government did not fund any retrofitting works to old construction. Although the government said in 2008 that it would retrofit hospitals and schools, no major changes were made.[14]
^Freund R.; Garfunkel Z.; Zak I.; Goldberg M.; Weissbrod T.; Derin B.; Bender F.; Wellings F.E.; Girdler R.W. (1970). "The Shear along the Dead Sea Rift (and Discussion)". Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences. 267 (1181): 107. Bibcode:1970RSPTA.267..107F. doi:10.1098/rsta.1970.0027.
^Mart Y.; Ryan W.B.F.; Lunina O.V. (2005). "Review of the tectonics of the Levant Rift system: the structural significance of oblique continental breakup". Tectonophysics. 395 (3–4): 209–232. Bibcode:2005Tectp.395..209M. doi:10.1016/j.tecto.2004.09.007.
^Grigoratos, Iason; Poggi, Valerio; Danciu, Laurentiu; Rojo, Graciela (14 February 2020). "An updated parametric catalog of historical earthquakes around the Dead Sea Transform Fault Zone". Journal of Seismology. 24 (4): 803–832. Bibcode:2020JSeis..24..803G. doi:10.1007/s10950-020-09904-9. S2CID211102430.
^National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information (1972). "Significant Earthquake Information". NOAA National Centers for Environmental Information. doi:10.7289/V5TD9V7K. Retrieved 22 June 2022. ((cite journal)): Cite journal requires |journal= (help)
