2021-07-22 | in Paper | one response
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 disturbances that preserved in the upper 260 m of a 723-m deep core drilled on the crest of a thrust-cored anticline in the western Qaidam Basin, NE Tibet.
1. Key Points:
• We interpret micro-faults, soft-sediment deformation, slumps, and detachment surfaces as paleoearthquake/tectonic indicators
• The core records five seismite clusters between 3.6 and 2.7 Ma, revealing episodic thrusting in relation to intense regional deformation
• During the clusters, regional deformation was concentrated more in the fold-and-thrust system than along regional major strike-slip faults
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.
To increase the visibility of activities of Paleoseismicity.org to Chinese in China and around the world and to promote potential interactions with Chinese, I opened an account for Paleoseismicity.org on the WeChat platform last week. The account was named “古地震”. (“古地震” means “paleoseismicity” in English).