Moment tensor solutions for small and moderate earthquakes in the Ibero-Maghreb region

Daniel Stich, Charles James Ammon, Jose Morales

Research output: Contribution to journalArticle

181 Citations (Scopus)

Abstract

We applied time domain moment tensor inversion of local and regional waveforms to small and moderate (Mw = 3.5-5.7) shallow earthquakes from the Iberian Peninsula, northern Morocco, and northern Algeria. For the 6+ years period from November 1995 to March 2002 and the previous Network of Autonomously Recording Seismograms (NARS) experiment, moment tensor solutions were obtained for 58 events, considerably increasing the total number of available solutions in the study area. For each event we performed a moment tensor inversion and a double-couple grid search. For simple faulting events the grid search is valuable as a quality test for its ability to reveal potential ambiguities of the solutions and to assess confidence limits of fault plane parameters or principal axes orientation. The computed mechanisms show regional consistency: A large part of the Iberian Peninsula is characterized by normal faulting mechanisms with SW-NE oriented T axes. Thrusting and SE-NW compression is dominant in Algeria. In the Alboran Sea, the westernmost part of the Mediterranean, and the transition between both regimes, strike-slip mechanisms dominate with approximately N-S oriented P axes. This pattern suggests a regional anomaly characterized by clockwise rotation of the principal horizontal stress orientations.

Original languageEnglish (US)
JournalJournal of Geophysical Research: Solid Earth
Volume108
Issue number3
StatePublished - Mar 10 2003

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Maghreb
moment tensor
earthquakes
Algeria
Tensors
Earthquakes
Faulting
peninsulas
tensors
moments
Iberian Peninsula
earthquake
faulting
grids
inversions
Morocco
confidence limits
seismograms
seismogram
fault plane

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

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abstract = "We applied time domain moment tensor inversion of local and regional waveforms to small and moderate (Mw = 3.5-5.7) shallow earthquakes from the Iberian Peninsula, northern Morocco, and northern Algeria. For the 6+ years period from November 1995 to March 2002 and the previous Network of Autonomously Recording Seismograms (NARS) experiment, moment tensor solutions were obtained for 58 events, considerably increasing the total number of available solutions in the study area. For each event we performed a moment tensor inversion and a double-couple grid search. For simple faulting events the grid search is valuable as a quality test for its ability to reveal potential ambiguities of the solutions and to assess confidence limits of fault plane parameters or principal axes orientation. The computed mechanisms show regional consistency: A large part of the Iberian Peninsula is characterized by normal faulting mechanisms with SW-NE oriented T axes. Thrusting and SE-NW compression is dominant in Algeria. In the Alboran Sea, the westernmost part of the Mediterranean, and the transition between both regimes, strike-slip mechanisms dominate with approximately N-S oriented P axes. This pattern suggests a regional anomaly characterized by clockwise rotation of the principal horizontal stress orientations.",
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Moment tensor solutions for small and moderate earthquakes in the Ibero-Maghreb region. / Stich, Daniel; Ammon, Charles James; Morales, Jose.

In: Journal of Geophysical Research: Solid Earth, Vol. 108, No. 3, 10.03.2003.

Research output: Contribution to journalArticle

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