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Soft-sediment deformation structures are often used as evidence for paleo-earthquakes. When several deformed horizons are present, one has to ask whether repeated slope failure at the sediment surface has built-up the stratigraphic record. Another option would be that a single failure event could have concurrently created surficial and sub-surface deformed horizons at different stratigraphic levels. The implications of these differing models are important for the timing of palaeo-earthquakes. In a new paper, Alsop et al. used the late Pleistocene Lisan Formation from the Dead Sea Basin to catalogue and establish key criteria that help distinguish surface versus sub-surface intrastratal deformation of soft-sediments. The paper is available for free for 50 days!

A recent study investigated seismogenic mass failure deposits that were preserved in a 457-m deep ICDP drilling (220-0 ka) from the Dead Sea depocenter. The study conducted a critical assessment and testing of the links between the occurrence of seismogenic mass failure, changes in water-level, and sedimentation rate driven by a changing climate.

1. Key Points:
• At the orbital- and millennial-scale, variable sedimentation rates are not a preconditioning factor for earthquake-triggered mass failures
• At the centennial- to decadal-scale, earthquake-triggered mass failures are not statistically correlated with lake-level state
• At the orbital- and millennial-scale, the mass failures are more frequent during lake-level high-stands with large-amplitude fluctuations

A recent study investigated turbidites that preserved in a 457-m deep ICDP drilling from the Dead Sea depocenter. This is the first work to show detailed information on turbidites in the region.

1. Key Points:

• Seismic origin for prehistoric turbidites is established by analyzing the underlying in situ deformation structures for each turbidite
• Data validate a previous hypothesis that soft-sediment deformation formed at the sediment-water interface in the Dead Sea
• The new approach permits a more confident geohazard assessment by improving the completeness of a paleoseismic archive

1. Key points

This is the first attempt to apply a computational fluid dynamic modeling-based quantitative “fossil seismograph” to develop a large earthquake record.

The record is calibrated to historic earthquakes, for which the Dead Sea area has a famously long span, and it confirms a clustered earthquake recurrence pattern and a group-fault temporal clustering model.

The record yields much shorter mean recurrence for large (≤ 1.4 kyr vs. 7-11 kyr) and moderate (≤ 500 yr vs. 1600 yr) earthquakes than previously obtained, thus reveals a much higher seismic hazard than previously appreciated on this slow-slipping plate boundary.

A new book on the Dead Sea Transform has been published by Springer:

DEAD SEA TRANSFORM FAULT SYSTEM: REVIEWS

Together with Prof. Zvi Garfunkel and Prof. Zvi Ben-Avraham, I am a co-editor of this book. The book focuses on various aspects of the fault system, from geophysics, to tectonics, paleolimnology, hydrology, seismicity, and PALEOSEISMICITY. Most relevant to this blog are the papers by Agnon and by Marco & Klinger.

• Shmulik Marco and Yann Klinger review in a new light the on-fault paleoseismic studies carried out along the DST.
• Amotz Agnon delves into the off-fault seismite archives (lake, cave).

Here is a link to the book on the Springer site: http://link.springer.com/book/10.1007%2F978-94-017-8872-4

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Here’s my list of recent publications that deal with paleoseismology and related topics.

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“Each of us has to decide what the right balance is between being effective and being honest.” 

I was thinking of this quote whilst listening to Mustapha Meghraoui’s talk during this week’s ISEMG conference in Mugla (Turkey). Mustapha was reviewing the seismic hazard potential of the northern stretch of the Dead Sea Rift, and he ended by identifying two prominent areas where there was a substantial long-term (1000 yr) slip deficit that strongly suggested heightened future earthquake potential. The quote above has nothing to do with earthquakes. Neither is it by Mustapha. Instead, it relates to global warming and was from the climate modeller and policy advocate Stephen Schneider. Nevertheless, it struck me that what Schneider was wrestling with a decade or so ago with climate change has parallels to what some earthquake geologists are wrestling with now: what do we do when we believe that the science demands action? more

Elisa Kagan sent me this nice field photo of the day – a drill core containing mass-movement evidence from the Dead Sea:

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I hope you have reserved some time for reading – here comes plenty of great new material on one of the most interesting tectonic features on earth, the Dead Sea Transform. The Israel Journal of Earth Sciences has published a special issue: The Dead Sea Rift as a natural laboratory for neotectonics and paleoseismology, Volume 58, Number 3 – 4. The papers are an outcome of the 2009 INQUA joint Israel/Jordan fieldtrip with the same name. I was lucky enough to have participated in that field trip. It was for sure one of the best field trips I ever had. more

This week’s centerfault is a very prominent one that you will know for sure – the Dead Sea Fault. The sinistral strike-slip fault marks the boundary between the Arabian plate and the Sinai. The entire system is more than 600 km long and has accommodated ~107 km of slip since Miocene. Magnitude 7 is no problem for this structure and the recurrence intervalls are short. more