Development of recent faulting in the southern Dead Sea Rift according to GPR imaging

Abstract

Abstract. The Arava valley is located at the southern part of the Dead Sea Rift (DSR). The continuous long-term tectonic activity in the area of Evrona fault zone, southern Arava valley, is evident with abundant geological expressions, while the neotectonic activity is not very clear on the surface. Furthermore, surficial inspection may give the impression that this prominent transform plate-boundary hardly produces meaningful evidence for recent tectonic activity.However, Ground Penetrating Radar (GPR) imaging, which has been conducted across the Evrona fault zone up to a depth of approximately 25 meters below the surface, reveals a dense inhomogeneous distribution of subsurface discontinuities. These hundreds of discontinuities per a kilometer length of GPR profile can be interpreted as sets of fractures and faults, with a variety of dip-slips, spatial orientations and depths. Another unique GPR observation reveals that the density of faults increases as a function of depth at the first 25 m. Moreover, the apparent dips of the faults suggest that they merge at a depth of a few tens of meters. This is confirmed by Shallow Seismic Reflection (SSR) observations conducted at the same locations, which generally identify a parent fault below group of faults that are detected by the GPR. According to both seismic and radar observations, a typical single active fault which is traced through the top hundred meters, changes its characteristics abruptly as it reaches a depth range of about 35-20 m below the surface. It then proceeds towards the surface in a series of splays. As a result of this mechanism, the tectonic displacement that accumulates along a plane of a parent fault is dispersed towards the surface. Linear Shear Strength Decrease (LSSD), damage distribution and fault propagation modelling of the relations between the structure and distribution of the faults and the mechanical properties of the alluvial materials of Evrona emphasize the splay mechanism and other phenomena revealed by the GPR images.Correspondence to: U. Basson (uri@geo-sense.com) An analysis of the faults detected by GPR in Evrona helped in evaluating the relative level of tectonic activity of an active fault zone. According to this approach, the neotectonic history of the Evrona fault zone during the last 45 000 yr is recorded. The GPR record reveals a peak in tectonic activity within 18 000-27 000 ybp. This peak in tectonic activity is about 37% higher than the average tectonic activity of the whole period. The level of tectonic activity in the recent period recorded by GPR (0-9000 ybp) is about 70% of the average tectonic activity and about 50% of the peak activity. These values and the decreasing trend in the tectonic activity since the peak wave suggest that the most recent period is tectonically quiet.

The door to Dor: Tracing unseen anthropogenic impact in an ancient port

“…Lazar et al, 2018) that affect more conventional methods used in archaeology and neotectonics, such as ground‐penetrating radar (e.g. Basson & Ginzburg, 2009; Basson et al, 2002; Bristow & Jol, 2003; Conyers, 2004; Rogers et al, 2012). The ease of use and quick scanning capability means that large areas can be covered in a relatively short time.…”

Geology and Evolution of the Southern Dead Sea Fault with Emphasis on Subsurface Structure

“…The southern part of the Arava Valley is marked by a structural saddle, resulting from mild compression (Garfunkel 1981, Garfunkel & Ben-Avraham 2001, Basson et al 2002. This compression can clearly be seen in upwarping Neogene and younger sediments.…”

“…According to Ginat & Avni (1994) the saddle, located 50-70 km north of the Gulf of Elat, was high and wide enough to allow a major drainage line to flow westward across the Dead Sea Fault into the Negev during the Pliocene. In the southern section of the Arava, just north of the Gulf of Elat, compressional features developed in the sedimentary fill (Basson et al 2002). These structures are young and formed as a result of recent changes in the geometry of the longitudinal master faults.…”

Evidências tectônicas no leste da Ilha do Marajó: integração de dados morfoestruturais e geofísicos

“…O GPR tem sido utilizado em inúmeras aplicações: a. hidrogeológicas (Beres & Haeni, 1991;Rea & Knight, 1995;Greaves et al 1996;Nakashima et al 2001;Marcelino et al 2005); b. arqueológicas (Vaughan, 1986;Cezar et al 2001); c. em estudos de engenharia (Dourado et al 2003); e d. na pesquisa de depósitos minerais (Porsani et al 2004). Em tempos mais recentes, o GPR tem-se destacado pela sua grande aplicabilidade na caracterização faciológica, no mapeamento estratigráfico de sucessões sedimentares de diferentes idades geológicas e no delineamento de estruturas tectônicas (p.e., Jol & Smith, 1991;Knoll et al 1991;Gawthorpe et al 1993;Dominic et al 1995;Bristow, 1995 a, b;Van Heteren et al 1998;Ellefsen, 1999;Uchua et al 1999;Dagallier et al 2000;Silva & Scherer, 2000;Basson et al 2002;Rashed et al 2003;Neal, 2004;Castro et al 2005;Maurya et al 2005;Patidar et al 2008). Porsani, 1999;Dourado et al 2001;Pereira, 2001;Borges & Porsani, 2002;Pereira et al 2003;Ceia et al 2004;Nogueira, 2004;Nogueira et al 2006;Moura et al 2005;Souza et al 2005).O uso do GPR na Amazônia tornou-se importante para desvendar a complexidade de sedimentação versus erosão durante o Neógeno no norte do Brasil, implicando no mapeamento de superfícies estratigráficas ch...…”

“…Este fato, associado a áreas delgadas livre de reflexões ou com reflexões caóticas onde ocorre interrupção brusca e deslocamento vertical desses segmentos de reflexões, sugere a presença de falhas. Muitos trabalhos têm interpretado planos de falha em seções GPR por meio de refletores interrompidos seguindo este mesmo padrão (p.e., Meschede et al 1997;Van Heteren et al 1998;Basson et al 2002;Rashed et al 2003;Ferry et al 2004;Patidar et al 2008). A presença de segmentos escalonados é condizente com sucessões de falhas com deslocamento por gravidade.…”