The submarine landscape of the Mediterranean Israeli continental - PowerPoint PPT Presentation

The submarine landscape of the Mediterranean Israeli continental slope Oded Katz 1 , Einav Reuven 1,2 , Einat Aharonov 2 1. Geological Survey of Israel 2. The Hebrew University of Jerusalem, Israel

This work: -3 LS Water Step We study the bathymetry and depth (m) -250 near surface geology off the -500 coast of Israel. -750 This is now feasible due to a Haifa -1000 recently released bathymetry grid: -1250 • National bathymetric grid – IOLR, -1500 GSI (Sade et al., 2006, 2008); Hadera • Resolution: 15 m grid till water -1750 depth of 700 and 50 m grid till water Natanya depth of 1750 m. Tel Aviv Motivation: 1. Connecting surface geomorphic features to past and present Ashdod geological processes; 40 km 2. Hazard evaluation (landslides, Ashqelon active faulting).

Objectives of the work: -3 LS Water Step 1. Mapping landslides and related depth (m) -250 surface features (steps trenches); 2. Analyzing landslide mechanics, -500 slope stability and triggering -750 conditions; Haifa 3. Hazard mapping (seismic and -1000 infrastructure related: gas lines -1250 and facilities). -1500 Hadera Studied area: -1750 Israeli continental slope, water depth Natanya range 100 – >1000 m. Tel Aviv Previous works: Almagor and Garfunkel, 1979; Almagor, 1983; Garfunkel and Almagor, 1985; Ashdod Gradmann et al., 2005; Mart and Ryan, 40 km 2007; and more. Ashqelon

Funding : • Steering Committee for Earthquake Preparedness, Israel (2011- 12) - to GSI; • Ministry of Science and Technology (2012-2014): 1. Katz, O. (GSI), Aharonov, E. (HU), Klar, A. (Technion); 2. Makovsky, Y. (UH), Tibor, G. (IOLR), Kamishny, A. (BGU). הטיסרבינואה ןוינכטה תירבעה לארשיל יגולונכט ןוכמ םילשוריב

Continental slope off the Israeli coast A A’ Haifa A’ x10 vertical exaggeration A TA Ashdod 0 Water -250 No vertical exaggeration -500 depth (m) -750 -1000 -1250 -1500 Slope = 4 ° -1750

Continental slope offshore Canyon Land Israel; 0 -250 -500 -750 Haifa -1000 -1250 Open Slope with landslides -1500 -1750 Hadera Tel Aviv Ashdod (Why are there two provinces of different behavior?)

Large geomorphic features Dor disturbance (e.g. Almagor & Garfunkel, 1979) 0 -250 -500 10 km -750 Haifa -1000 -1250 -1500 Palmahim disturbance -1750 Hadera Tel Aviv 15 km Ashdod

Geological structure (Almagor and Garfunkel, 1979) 1 2 1. Pliocene-Quaternary silt and clay 2. Messinian evaporites

Salt tectonic offshore Israel Gradmann et al., 2005

Similarity of landslides geometry: t/l ~ 0.1 e.g. Klar, Aharonov, Katz, 2011 l H t Thus: Palmahim disturbance: l ~ 10 km → t ~ 1 km Shallow landslides: l ~ 1 km → t ~ 0.1 km

Landslide Mapping targets (south of Haifa): Slope Map with mapped Step/channel 1. Landslides (scars and deposits); landslides >15.0 ° 2. Step like lineaments (growth 33.0 ° N Slope 12.5 ° faults); angle 3. Trenches 10.0 ° Haifa This talk 7.5 ° 2 In this talk : 5.0 ° • Map of submarine landscape 2.5 ° in the area south of Haifa. Hadera 1 0.0 ° Natanya Tel Aviv 32.0 ° N 34.0 ° E 35.0 ° E Ashdod 0 25 50 km Ashqelon

Simple landslide Simple (and apparently younger) landslide S W E N Scar Scar Scar Step ~50 m A Step Step Step Toe Scar A ’ Toe 1 km Map view Perspective view A ’ A -300 Water depth (m) Slope = 15 ° -350 -400 -450 1:2 vertical exaggeration -500 0 500 1000 1500 Distance (m)

Complex landslide Complex (and apparently older) landslide A ’ S N Scar N S Scar Scar Step Step 2 km A Map view Perspective view -200 A ’ -250 A Water depth (m) -300 Slope = 25 ° -350 -400 -450 -500 1:2 vertical exaggeration -550 0 500 1000 1500 2000 Distance (m)

Large landslide Landslide Step/channel W E 40 km Haifa 5 km Hadera Map view Natanya N S Tel Aviv Ashdod Perspective view Ashqelon

Landslide Steps (growth faults) Step/channel 40 km Haifa Hadera Natanya Tel Aviv Ashdod Ashqelon

Step Steps (growth faults) N S W E E W A Step Step Step Step ~85 m A ’ 2 km Map view ~60 m Perspective view A A’ Line 2057-IS Base Pliocene Base Messinian Fault interpretation: Ecolog

Landslide Channel Trench Line 2057-IS Step/channel W E 4 km 40 km Haifa Base Pliocene Map view Base Messinian Hadera Natanya E W ~40 m Tel Aviv Ashdod Perspective view Ashqelon

Landslide Summary Step/channel • Slides become smaller northwards, and are characteristic of the southern province. 40 km • Landslides, both young and old, either Haifa emerge from the over-steepened steps (growth faults), or are displaced by them, and hence submarine landslides and steps are apparently contemporaneous. These slides are smaller and different than the two Hadera main disturbances, Palmahim and Dor. • Salt dynamics at depth is a main drive for at Natanya least some of the shallow landslides. • The above preliminary results testify to the complicated and highly dynamic nature of Tel Aviv the studied continental slope, yet to be revealed. Future finding are relevant to the energy industry and infrastructure as well as Ashdod to general seismic hazard analysis and regulations. Ashqelon