Lower-crustal strength under the Dead Sea basin from local earthquake data and rheological modeling

F. Aldersons*, Z. Ben-Avraham, A. Hofstetter, E. Kissling, T. Al-Yazjeen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

98 Scopus citations

Abstract

We studied the local seismicity of the Dead Sea basin for the period 1984-1997. Sixty percent of well-constrained microearthquakes (ML≤3.2) nucleated at depths of 20-32 km and more than 40% occurred below the depth of peak seismicity situated at 20 km. With the Moho at 32 km, the upper mantle appeared to be aseismic during the 14-year data period. A relocation procedure involving the simultaneous use of three regional velocity models reveals that the distribution of focal depths in the Dead Sea basin is stable. Lower-crustal seismicity is not an artifact created by strong lateral velocity variations or data-related problems. An upper bound depth uncertainty of ±5 km is estimated below 20 km, but for most earthquakes depth mislocations should not exceed ±2 km. A lithospheric strength profile has been calculated. Based on a surface heat flow of 40 mW m-2 and a quartz-depleted lower crust, a narrow brittle to ductile transition might occur in the crust around 380°C at a depth of 31 km. For the upper mantle, the brittle to ductile transition occurs in the model at 490°C and at 44 km depth. The absence of micro-seismicity in the upper mantle remains difficult to explain.

Original languageEnglish
Pages (from-to)129-142
Number of pages14
JournalEarth and Planetary Science Letters
Volume214
Issue number1-2
DOIs
StatePublished - 10 Sep 2003

Funding

FundersFunder number
Ministry of Energy and Infrastructure of Israel

    Keywords

    • Brittle
    • Dead Sea
    • Ductile
    • Focal depth
    • Heat flow
    • Lower crust
    • Rheology
    • Rifts
    • Seismicity

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