1887
Volume 56, Issue 4
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

Migration techniques, currently used in seismic exploration, are still scarcely applied in earthquake seismology due to the poor source knowledge and sparse, irregular acquisition geometries. At the crustal scale, classical seismological studies often perform inversions based on the arrival time of primary phases (P‐ and S‐waves) but seldom exploit other information included in seismic records. Here we show how migration techniques can be adapted to earthquake seismology for converted wave analysis. As an example, we used data recorded by a dense local seismic network during the 2002 Molise aftershock sequence. In October and November 2002, two moderate magnitude earthquakes struck the Molise region (southern Italy), followed by an aftershock sequence lasting for about one month. Local earthquake tomography has provided earthquake hypocenter locations and three‐dimensional models of P and S velocity fields. Strong secondary signals have been detected between first‐arrivals of P‐ and S‐waves and identified as SP transmitted waves. In order to analyse these waves, we apply a prestack depth migration scheme based on the Kirchhoff summation technique. Since source parameters are unknown, seismograms are equalized and only kinematic aspects of the migration process are considered. Converted wave traveltimes are calculated in the three‐dimensional (3D) tomographic models using a finite‐difference eikonal solver and back ray tracing. In the migrated images, the area of dominant energy conversion corresponds to a strong seismic horizon that we interpreted as the top of the Apulia Carbonate Platform and whose geometry and position at depth is consistent with current structural models from existing commercial seismic profiles, gravimetric and well data.

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2008-06-28
2024-04-19
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References

  1. ChavarriaJ.A., MalinP.E., CatchingsR.D. and ShalevE.2003. A look inside the San Andreas Fault at Parkfield through vertical seismic profiling. Science302, 1746–1748.
    [Google Scholar]
  2. Chavez‐PerezS. and LouieJ.N.1998. Crustal imaging in southern California using earthquake sequences. Tectonophysics286, 223–236.
    [Google Scholar]
  3. ChiarabbaC., De GoriP., ChiaraluceL., BordoniP., CattaneoM., De MartinM. et al . 2005. Mainshocks and aftershocks of the 2002 Molise seismic sequence, southern Italy. Journal of Seismology9, 487–494.
    [Google Scholar]
  4. DemanetD., MargheritiL., SelvaggiG. and JongmansD.1998. Upper crustal structure in the Potenza area (Southern Apennines, Italy), using Sp converted waves. Annali di GeofisicaXLI, 105–119.
    [Google Scholar]
  5. FracassiU., BurratoP., BasiliR., BenciniR., Di BucciD. and ValensiseG.2004. Shallow NE–SW extension and deep E–W right‐lateral slip: Coexisting seismogenic mechanisms as an expression of southern Italy geodynamics. 23rd Gruppo Nazionale Geofisica Terra Solida Symposium, Rome, Italy, Expanded Abstracts, pp. 200–202.
  6. HoleJ.A.1992. Nonlinear high‐resolution three‐dimensional seismic traveltime tomography. Journal of Geophysical Research97, 6553–6562
    [Google Scholar]
  7. JamesD.F., ClarkeT.J. and MeyerR.P.1987. A study of seismic reflection imaging using microearthquake sources. Tectonophysics140, 65–79.
    [Google Scholar]
  8. LatorreD.2004. Imagerie sismique du milieu de propagation à partir des ondes directes et converties: application à la région d'Aigion (Golfe de Corinthe, Grèce). PhD thesis, Université de Nice‐Sophia Antipolis, France .
  9. LatorreD., VirieuxJ., MonfretT. and Lyon‐CaenH.2004a. Converted seismic wave investigation in the Gulf of Corinth from local earthquakes. Comptes Rendus Geosciences336, 259–267.
    [Google Scholar]
  10. LatorreD., VirieuxJ., MonfretT., MonteillerV., VanorioT., GotJ.‐L. et al . 2004b. A new seismic tomography of Aigion area (Gulf of Corinth, Greece) from the 1991 data set. Geophysical Journal International159, 1013–1031.
    [Google Scholar]
  11. Le MeurH., VirieuxJ. and PodvinP.1997. Seismic tomography of the Gulf of Corinth: A comparison of methods. Annali di GeofisicaXL, 1–25.
    [Google Scholar]
  12. LouieJ.N., Chávez‐PérezS., HenrysS. and BannisterS.2002. Multimode migration of scattered and converted waves for the structure of the Hikurangi slab interface, New Zealand. Tectonophysics355, 227–246.
    [Google Scholar]
  13. MicheliniA. and McEvillyT.V.1991. Seismological studies at Parkfield, I, Simultaneous inversion for velocity structure and hypocentres using cubic b‐splines parameterization. Bulletin of the Seismological of Society of America81, 524–552.
    [Google Scholar]
  14. MostardiniF. and MerliniS.1986. L'Appenino centro‐meridionale – Sezioni geologiche e proposta di modello strutturale. Memorie della Società Geologica Italiana35, 177–202.
    [Google Scholar]
  15. NicolaiC. and GambiniR.2007. Structural architecture of the Adria platform‐and‐basin system. Bollettino Società Geologica Italiana7, 21–37.
    [Google Scholar]
  16. NisiiV., ZolloA. and IannacconeG.2004. Depth of a midcrustal discontinuity beneath Mt. Vesuvius from the stacking of reflected and converted waves on local earthquake records. Bulletin of the Seismological Society of America94, 1842–1849.
    [Google Scholar]
  17. PodvinP. and LecomteI.1991. Finite difference computation of traveltime in very contrasted velocity model: A massively parallel approach and its associated tools. Geophysical Journal International105, 271–284.
    [Google Scholar]
  18. RoureF., CaseroP. and ViallyR.1991. Growth process and melange formation in the southern Appenines accretionaly wedge. Earth and Planetary Science Letters102, 395–412.
    [Google Scholar]
  19. SellaM., TurciC., and RivaA.1988. Sintesi geopetrolifera della Fossa Bradanica (avanfossa della catena appenninica meridionale). Memorie della Società Geologica Italiana41, 87–107.
    [Google Scholar]
  20. StecklerM.S., AgostinettiN.P., WilsonC.K., RoselliP., SeeberL., AmatoA. et al . 2008. Crustal structure in the Southern Apennines from teleseismic receiver functions. Geology (in press).
    [Google Scholar]
  21. StroujkovaA.F. and MalinP.E.2000. A magma mass beneath Casa Diablo? Further evidence from reflected seismic waves. Bulletin of the Seismological Society of America90, 500–511.
    [Google Scholar]
  22. ThurberC.H.1983. Earthquake locations and three‐dimensional crustal structure in the Coyote Lake area, Central California. Journal of Geophysical Research88, 8226–8236.
    [Google Scholar]
  23. ThurberC.H.1993. Local earthquake tomography: Velocity and Vp/Vs‐theory. In: Seismic Tomography: Theory and Pratice (eds H.M.Iyer and K.Hirahara ). CRC Press, Boca Raton , FL .
    [Google Scholar]
  24. ToomeyD.R. and FoulgerG.R.1989. Tomographic inversion of local earthquake data from the Hengill‐Grensdalur central volcano complex, Iceland. Journal of Geophysical Research94, 17,497–17,510.
    [Google Scholar]
  25. WesselP. and SmithW.H.F.1991. Free software helps map and display data. Eos Transactions, American Geophysical Union72, 441.
    [Google Scholar]
  26. YilmazO.2001. Seismic Data Analysis: Processing, Inversion and Interpretation of Seismic Data . SEG.
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