New Modes of Sinkhole Formation along the Dead Sea Shorelines (Israel): Observations from InSAR, LiDAR, Time-lapse Camera, and Water Analysis

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1 New Modes of Sinkhole Formation along the Dead Sea Shorelines (Israel): Observations from InSAR, LiDAR, Time-lapse Camera, and Water Analysis G. Baer, Y. Avni, M. Shviro, R. Nof, I. Gavrieli, N. Lensky, Y. Yechieli, I. Haviv, E. Dente Geological Survey of Israel, Ben Gurion University, Geophysical Institute of Israel, Hebrew University, Jerusalem Fringe 2015 InSAR workshop, March, 2015, ESA-ESRIN Frascati, Italy

2 Overview Sinkhole formation mechanism along the Dead Sea Sinkhole hazards and precursory subsidence New modes of Seasonal sinkholes: 1. Along active riverbeds 2. Away from active riverbeds Fringe 2015 InSAR workshop, March, 2015, ESA-ESRIN Frascati, Italy

3 Sinkhole Formation Mechanism Ezersky et al., 2009 Abelson et al., 2003

4 # Sinkholes Dead Sea sinkhole evolution Sinkholes/yr # sinkholes Sinkholes/year Year Dead Sea water level drop Water level bsl (m)

5 Sinkhole hazard LiDAR DEM Differential map:

6 14/12/ /12/ /9/ /10/ cm First typical precursory subsidence on highway 90, Dead Sea, COSMO SkyMed, 16 days, LiDAR 0.5 m/pixel DEM Nof et al., 2013

7 7/10/ /10/ End 2014: Subsidence increases

8 7/10/ /10/2014 1/2/ m deep 5 m diameter Cracks and local subsidence on the road

9 7/10/ /10/ /2/2015 Road is now diverted 2.5 years between initial subsidence and exposure: cavity held by geotechnical sheet

10 Seasonal sinkholes and subsidence along ושקיעות קרקע התפתחות בולענים active riverbeds : בנחל חבר

11 LiDAR DEM of Hever sinkhole site Resolution: 0.5 m/pixel

12 Long-term changes (Years)

13 Long-term changes (Years) Northward and eastward migration of sinkholes 2. Filling of existing sinkholes by gravel

14 Short-term (16 days) changes

15 Subsidence volume m 3 /day Flood date 0 Jan-12 Jul-12 Jan-13 Jul-13 Jan-14 Jul-14 Jan-15 Shviro et al., in prep.

Subsidence volume m 3 /day 16 12 8 4 Flood date 0 Jan-12

16 Subsidence volume m 3 /day Flood date 0 Jan-12 Jul-12 Jan-13 Jul-13 Jan-14 Jul-14 Jan-15 Shviro et al., in prep.

17 Ze elim Alluvial Fan LiDAR 2013 Drainage Seepage LiDAR 2013 LiDAR 2005

18 Ze elim Alluvial Fan LiDAR 2013 Drainage Seepage Mechanism

Flood and spring water properties Spring Density=1.205 Na/Cl=0.89 δ 18 O= 6.

20 Flood and spring water properties Spring Density=1.205 Na/Cl=0.89 δ 18 O= Flood Density=1.005 Na/Cl=0.33 δ 18 O= Flood Density=1.007 Na/Cl=0.35 δ 18 O= 9.7 Drainage Seepage

21 Interim summary Flash-floods drain into existing or newly formed sinkholes Subsurface salt dissolves rapidly New sinkholes are formed and the overlying ground subsides Additional ponding areas and conduits form Accelerated subsidence and more sinkholes Subsurface water flow at velocity of ~ 500 m/hr (~ 15 cm/sec)

22 What happens away from active riverbeds?

23 active riverbed 12 Subsidence volume m 3 /day Flood date Jan-12 Jul-12 Jan-13 Jul-13 Jan-14 Jul-14 Jan-15 Shviro et al., in prep.

24 active riverbed 12 Subsidence volume m 3 /day Flood date Jan-12 Jul-12 Jan-13 Jul-13 Jan-14 Jul-14 Jan-15 Shviro et al., in prep.

25 last rain storm

26 Post winter InSAR time series

29 ~

33 Away from active riverbeds: 1. Groundwater level rises during a period of several months after rain storms 2. Salt layers dissolve as water level rises 3. Subsidence occurs, followed by sinkholes 4. Process is repeated after each rain storm

34 In Summary Two complementary seasonal sinkhole formation modes: out 1. Along active channels: Immediate acceleration due to direct drainage of flood water to the underlying salt layer and gradual recovery within weeks to several months Revealed and analysed by time-series InSAR 2. Away from active channels: Post-winter groundwater-level rise, gradual increase in subsidence rates into the midsummer, and gradual recovery within several months Avni et al., in prep.

35 A new sinkhole is born (in front of our camera)

37 Thank you! More about sinkholes in poster No. 69: Atzori et al., Thursday afternoon

PUBLICATIONS. Journal of Geophysical Research: Earth Surface

PUBLICATIONS. Journal of Geophysical Research: Earth Surface PUBLICATIONS Journal of Geophysical Research: Earth Surface RESEARCH ARTICLE Key Points: A self-accelerated active salt karst system is formed along the Dead Sea coast Land subsidence and sinkhole formation