Jordan River Delta Slumps Figure 2

North-south 3.5 kHz seismic-reflection profile A showing cross-sectional detail of submarine slump and correlation of seismic reflectors (B-E; with major, radiocarbon-dated lowstands of Dead Sea (Frumkin et al., 1991); m bsl is metres below sea level. Arrow indicates headwall scarp of slump. Two seismically triggered slump events are labeled 1 and 2 (see text for description).

Niemi and Ben-Avraham (1994)

Master Seismic Events Table

Charts, Plots, Maps, Images, etc.
Jordan River Delta

Image Description Source
Fig. 1 - Map Niemi and Ben-Avraham (1994)
Fig. 2 - Line A Niemi and Ben-Avraham (1994)
Fig. 3 - Line B Niemi and Ben-Avraham (1994)

Notes about the Survey and the interpretation of the data

Niemi and Ben-Avraham (1994) state the following:

To study active tectonic processes in the Dead Sea, >1250 km of 3.5 kHz high-resolution seismic-reflection data were collected with a 1 km grid spacing in the north basin. From analyses of the 3.5 kHz and Sparker single-channel seismic-reflection data (Neev and Hall, 1976, 1979), we mapped active faults flanking the margins of the deep north basin of the Dead Sea (Fig. 1). Adjacent to a segment boundary of the main fault, we discovered a large submarine slump characterized by backward rotational blocks covering an area 6.15 by 2.75 km (Fig. 1) and having a basal glide plane at ~10 m depth (Fig. 2). The toe of the slump is not very well developed. The headwall scarp is located in the stable bottomset region of the Jordan River delta on a slope of less than 1° in ~250 m water depth ~5.5 km south of the mouth of the river (Fig. 1).

Given the Dead Sea sediment characteristics and that gravity-induced sliding on slopes of less than 3° occurs only where silt and clay are overpressured and underconsolidated (Crans et al., 1980), we conclude that this large submarine slump was triggered by an earthquake. The Dead Sea bottom sediments consist of chemical precipitates (aragonite, calcite, and gypsum) and detrital mud interbedded with layers of rock salt (Elazari-Volcani, 1943; Neev and Emery, 1967; Garber, 1980; Levy, 1984, 1988) that are continuous across the deep basin (Ben-Avraham et al., 1993). Geotechnical measurements on short cores from the Jordan River delta show that the sediments are consolidated and have a high effective angle of internal friction (Almagor, 1990). The predominance of chemical precipitates also leads to a low sediment porosity (Stiller et al., 1983). These characteristics show that Dead Sea sediments are extremely stable in the bottomset slopes of the Jordan River delta and that slump was produced by ground shaking caused by a large earthquake.