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Elat Sabhka Trenches

Maps, Aerial Views, Trench Logs, Seismic Lines, Age Models, Cores, and Photo
Maps, Aerial Views, Trench Logs, Seismic Lines, Age Models, Cores, and Photo

Maps

  • Fig. 1 Location Map from Kanari et al (2020)
  • Fig. 2a Bathymetric Map from Kanari et al (2020)
  • Fig. 3a Fault Map from Kanari et al (2020)
  • Fig. 3b Fault Map from Kanari et al (2020)
  • Fig. 9 Fault Map from Kanari et al (2020)

Embedded Earthquake hazards of the Elat-Elot Area Map
Aerial Views

  • Elat Sabkha Trench 1 area in Google Earth
  • Elat Sabkha Trench 3 area in Google Earth

Trench Logs and Photomosaics

Location Map

Fig. 6e

(e) map of trenches T1 and T3 area detailing the locations of all other features in the figure (panels a-d). For the reader's convenience, a high-resolution version of the figure is available in the supplementary material SM2

Kanari et al (2020)


Trench T1

Fig. 6b

Liquefaction features and their spatial extent. (c) T1 liquefaction fluid escape structures (interpreted in yellow on photo) and its charcoal ET02 sample; white arrow points out liquefaction related feature.

Kanari et al (2020)


Trench T3

Wide View

Fig. 5b

Trench T3 log of the fault zone: The top 80 cm of the trench were disturbed by farming (marked by white dashed boundary). U1-U8 are stratigraphic units and F1-F11 are interpreted fault strands (see text for detail). Yellow hexagons mark charcoal samples locations; dated samples have adjacent radiocarbon age determinations presented. E1 and E2 are the interpreted event horizons which represent the faulting events (see text for detail). (b) The complete 0–7 m fault zone log; blue rectangle marks the area of panel (a); The presented log is simplified for clarity of the figure; a high-resolution more detailed log is available in the supplementary material SM1

Kanari et al (2020)


Detailed Blowup

Fig. 5a

Trench T3 log of the fault zone: The top 80 cm of the trench were disturbed by farming (marked by white dashed boundary). U1-U8 are stratigraphic units and F1-F11 are interpreted fault strands (see text for detail). Yellow hexagons mark charcoal samples locations; dated samples have adjacent radiocarbon age determinations presented. E1 and E2 are the interpreted event horizons which represent the faulting events (see text for detail). (a) detailed blow-up of the 3–5 m faulted strata in the fault zone

Kanari et al (2020)


Sand Blow SB1

Fig. 6a

Liquefaction features and their spatial extent. (a) Trench log of Sand blow 1 structure (SB1) in T3 and its logged stratigraphic structure; boundaries of sand blow outlined in black dashed rectangle; L1-L7 are stratigraphic units of the West Sabkha (see text for detail). Yellow hexagons mark charcoal samples locations; dated samples have adjacent radiocarbon age determinations presented.

Kanari et al (2020)


Sand Blow SB2

Fig. 6b

Liquefaction features and their spatial extent. (b) photo mosaic of Sand blow 2 structure (SB2) in T3; no detailed log is available for SB2

Kanari et al (2020)


Seismic Lines

Location Map

Fig. 3b

The Avrona Fault offshore and the lineaments georeferenced to a modern satellite image, and the dataset used in the current study: location of seismic reflection profiles SI-4047 (light-blue circles mark CMP numbers), GI-2108 (yellow circles mark CMP numbers) and GI-2210 (blue line) and the paleoseismic trenches T1 and T3. The Hotel District of Elat is marked for reference to its vicinity to the surface rupture prone area. The seismic profiles are presented in Fig. 4.

Kanari et al (2020)


Line GI-2108

Fig. 4a

Seismic line GI-2108 extending E-W on the southern part of the Elat Sabkha including interpretation of the Avrona Fault strands (yellow) and the Elat Fault (green); specific CMP points at interpreted fault strands are marked in red triangles (same CMPs are marked in Fig. 9).

Kanari et al (2020)


Line GI-2210

Fig. 4c

High-resolution seismic line GI-2210 extending S-N on the eastern part of the Elat Sabkha including interpretation of the Avrona Fault strands (yellow); This line overlaps line SI-4047 (panel b) while the high resolution allows to identify fault offsets and deformation reaching up close to the surface. See Fig. 3 for location of the lines.

Kanari et al (2020)


Line SI-4047

Fig. 4b

Seismic line SI-4047 extending S-N on the eastern part of the Elat Sabkha including interpretation of the Avrona Fault strands (yellow) and the Elat Fault (green); specific CMP points at interpreted fault strands are marked in red triangles (same CMPs are marked in Fig. 9).

  • AF = Anticlinal Folds
  • SF = Synclinal Folds


Kanari et al (2020)


Seismic Line Across the Gulf of Aqaba

Fig. 2b

composite marine high-resolution seismic reflection profile across the gulf showing the six faults dividing the basin into the Elat sub-basin, Ayla horst, and Aqaba sub-basin (after Hartman et al., 2014). The location of the composite profile is marked in a pink line and the coastline of the GAE marked in black.

Kanari et al (2020))


Age Models

Age Model for Events E1 and E2 in Trench T3

Fig. 8a

Radiocarbon age models for the deformation and liquefaction events in trench T3 using OxCal software: (b) OxCal modeled age for faulting events E1 and E2 using samples from stratigraphic units U0, U1, U4 and U5 from the fault zone. Model calculated using OxCal 4.3.2 and IntCal13 calibration curve (Bronk Ramsey, 2017; Reimer et al., 2013).

Kanari et al (2020)


Age Model for Units L6 and L7 and Sand Blows SB1 and SB2 in Trench T3

Fig. 8a

Radiocarbon age models for the deformation and liquefaction events in trench T3 using OxCal software: (a) OxCal modeled age for liquefaction event using samples from stratigraphic units L6 and L7 from SB1 and the liquefied sand from SB2

Kanari et al (2020)


Sediment Accumulation Rate in Trench T3

Fig. 7

Sediment accumulation rate estimation for trench T3: using the calibrated year BP ages of the radiocarbon ages from the bottom of the trench and the measured depth to the top of the trench, an accumulation rate was calculated. The triangles are radiocarbon ages with 2-sigma error bars and the solid lines are the linear interpolation regressions. The fault zone ages (blue) result in 0.9 mm/year accumulation rate, while the west sabkha SB1 ages (orange) result in 1.7 mm/year. Locations of charcoal samples on trench logs are presented in Figs. 5 and 6. Radiocarbon age determinations in Table 1.

Kanari et al (2020)


Cores

Location Map

Figure 2

Map of marine and continental data presented here: the submarine Avrona Fault mapped by Hartman (2015) in white line, paleoseismic trench locations (yellow lines), piston cores in red circles; Inset: blow-up of land survey data collections (trenches in yellow and GPR lines in black; GPR data not presented here); red star: the location of the fault observed in trench T3 (Fig. 3); red line: the suggested fault trace of the on-land Avrona Fault, traced between the edge of the submarine fault and the surface rupture of the 1068 AD and 1458 AD earthquakes observed in T3.

Kanari et al (2015)


Core P27

Figure 4

Grain size distribution (downcore spectrum of % volume per grain diameter) and 14C age determinations (cal BC/AD) of core P27 from the northern Gulf of Aqaba Elat. 14C age calibrated using Calib 7.0 (Stuiver and Reimer, 1993) and Marine13 calibration curve (Reimer et al, 2013).

Kanari et al (2015)


Cores P17, P22, and P29

Figure 5

Grain size distribution (downcore spectrum of % volume per grain diameter) of cores P17 (540 mbsl), P22 (316 mbsl) and P29 (282 mbsl) from the Northern Gulf of Aqaba-Elat; see Fig. 2 for core locations

Kanari et al (2015)


Photo of Liquefaction from 1995 Nuweiba Quake

Location Map

Fig. 6e

(e) map of trenches T1 and T3 area detailing the locations of all other features in the figure (panels a-d). For the reader's convenience, a high-resolution version of the figure is available in the supplementary material SM2

Kanari et al (2020)


Photo

Fig. 6d

Liquefaction features and their spatial extent. (d) liquefaction evidence from the 1995 Nuweiba M 7.2 earthquake, still visible today in the vicinity of T1; white arrow points out liquefaction related feature; photo taken in December 2011

Kanari et al (2020)


Master Seismic Events Table
Master Seismic Events Table

Calculators
Normal Fault Displacement

Source - Wells and Coppersmith (1994)

Variable Input Units Notes
cm.
cm.
m/s Enter a value of 655 for no site effect
Equation comes from Darvasi and Agnon (2019)
Variable Output - not considering a Site Effect Units Notes
unitless Moment Magnitude for Avg. Displacement
unitless Moment Magnitude for Max. Displacement
Variable Output - Site Effect Removal Units Notes
unitless Reduce Intensity Estimate by this amount
to get a pre-amplification value of Intensity
  

Site Effect Explanation

The value given for Intensity with site effect removed is how much you should subtract from your Intensity estimate to obtain a pre-amplification value for Intensity. For example if the output is 0.5 and you estimated an Intensity of 8, your pre-amplification Intensity is now 7.5. An Intensity estimate with the site effect removed is helpful in producing an Intensity Map that will do a better job of "triangulating" the epicentral area. If you enter a VS30 greater than 655 m/s you will get a positive number, indicating that the site amplifies seismic energy. If you enter a VS30 less than 655 m/s you will get a negative number, indicating that the site attenuates seismic energy rather than amplifying it. Intensity Reduction (Ireduction) is calculated based on Equation 6 from Darvasi and Agnon (2019).

VS30 Explanation

VS30 is the average seismic shear-wave velocity from the surface to a depth of 30 meters at earthquake frequencies (below ~5 Hz.). Darvasi and Agnon (2019) estimated VS30 for a number of sites in Israel. If you get VS30 from a well log, you will need to correct for intrinsic dispersion. There is a seperate geometric dispersion correction usually applied when processing the waveforms however geometric dispersion corrections are typically applied to a borehole Flexural mode generated from a Dipole source and for Dipole sources propagating in the first 30 meters of soft sediments, modal composition is typically dominated by the Stoneley wave. Shear from Stoneley estimates are approximate at best. This is a subject not well understood and widely ignored by the Geotechnical community and/or Civil Engineers but understood by a few specialists in borehole acoustics. Other considerations will apply if you get VS30 value from a cross well survey or a shallow seismic survey where the primary consideration is converting shear slowness from survey frequency to Earthquake frequency. There are also ways to estimate shear slowness from SPT & CPT tests.

Estimate PGA of Sand Boils and Convert PGA to Intensity
Estimate PGA of Sand Boils Fig. 9.

Proposed boundary curves relating thickness of nonliquefiable surface layer to thickness of the liquefiable zone as a function of peak earthquake accelerations required to induce venting or ground rupturing at the surface. From Ishihara (1985).

Obermeier (1996)


Sand Blow Sand Blow Thickness (m) Thickness of Surface Layer (m)
SB1 0.5 ?
SB2 0.3 ?
Variable Input Units Notes
g Peak Horizontal Ground Acceleration
Variable Output
(No Site Effect)
Units Notes
unitless Conversion from PGA to Intensity using Wald et al (1999)
  

References
References