Slip deficit and temporal clustering along the Dead Sea fault from paleoseismological investigations

Marthe Lefevre,Mahmoud Al-Qaryouti,Maryline Le Béon,Yann Klinger,Khaled Moumani

doi:10.1038/s41598-018-22627-9

Abstract

Temporal distribution of earthquakes is key to seismic hazard assessment. However, for most fault systems shortness of large earthquake catalogues makes this assessment difficult. Its unique long earthquake record makes the Dead Sea fault (DSF) exceptional to test earthquake behaviour models. A paleoseismological trench along the southern section of the DSF, revealed twelve surface-rupturing earthquakes during the last 8000 years, of which many correlate with past earthquakes reported in historical chronicles. These data allowed us building a rupture scenario for this area, which includes timing and rupture length for all significant earthquakes during the last two millenaries. Extending this rupture scenario to the entire DSF south of Lebanon, we were able to confirm the temporal-clustering hypothesis. Using rupture length and scaling laws, we have estimated average co-seismic slip for each past earthquake. The cumulated slip was then balanced with long-term tectonic loading to estimate the slip deficit for this part of DSF over the last 1600 years. The seismic-slip budget shows that the slip deficit is similarly high along the fault with a minimum of 2 meters, which suggests that an earthquake cluster might happen over the entire region in the near future.

Highlights

Successions of intense periods of seismic activity rupturing significant length of a fault followed by longer periods of seismic quiescence have been documented along several strike-slip faults[1,2,3,4,5,6], suggesting that temporal clustering of earthquakes might be a common behaviour for major strike-slip faults
These new data were integrated with the corpus of data already available to propose an earthquake catalogue including timing and rupture length for significant earthquakes for at least the last 1600 years, for the area from southern Lebanon to the Gulf of Aqaba
The Wadi Araba fault section is mostly linear with two noticeable fault jogs, the Yotvata playa, which is an extensional relay zone, and the compressional bend located at the Jabal al-Risha

Summary

Paleoseismological Observations

The Wadi Araba fault section is mostly linear with two noticeable fault jogs, the Yotvata playa, which is an extensional relay zone, and the compressional bend located at the Jabal al-Risha. A massive reddish sandy unit is popping up through the trench stratigraphy between marks 3 and 9, which is interpreted as a small push-up, based on strong similarity in material and appearance with the observed push-up located a hundred meters south of our trench (Fig. S1). This unit is affected by numerous fractures defining a positive flower structures consistent with compressional deformation. Liu-Zeng et al.[29] showed that under favorable conditions surface rupture of local moderate-magnitude earthquakes could be preserved in the stratigraphy

Earthquake rupture length in the Wadi Araba

Slip deficit assessment and implication for seismic hazard

Author Contributions

Findings

Additional Information