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Morphology and depth of reflectors from 2D non-linear inversion of seismic data
Author(s)
Language
English
Status
Published
Peer review journal
Yes
Pages (printed)
157-178
Issued date
2006
Keywords
Abstract
We present here two methods to obtain reflection images of upper
crust seismic reflectors. The techniques are based on migration and waveform
coherence analysis of reflected seismic phases recorded in local earthquake seismograms
and in active seismic data.
The first method is a move-out and stack of reflected seismic phases in local
earthquake recordings. The theoretical travel times of reflected/converted
phases in a 1D medium for a given interface depth and velocity model are used
to align the recordings in time. The locations and origin times of events are initially
estimated from the P and S arrival times. Different seismic gathers are
obtained for each reflected/converted phase at the interface under consideration,
and the best interface depth is chosen as that which maximizes the value
of a semblance function computed on moved-out records. This method has
been applied to seismic records of microearthquakes that have occurred at the
Mt. Vesuvius volcano, and it confirms the reports of an 8- to 10-km-deep seismic
discontinuity beneath the volcano that was previously identified as the
roof of an extended magmatic sill.
The second is a non-linear 2D method for the inversion of reflection travel
times aimed at the imaging of a target upper-crust reflector. This method is specifically
designed for geophysical investigations in complex geological environments
(oil investigations, retrieving of images of volcano structures) where the
presence of complex structures makes the standard velocity analysis difficult
and degrades the quality of migrated images. Our reflector is represented by
nodes of a cubic-spline that are equally spaced at fixed horizontal locations. The
method is based on a multiscale approach and uses a global optimization technique
(genetic algorithm) that explores the whole of the parameter space, i.e.
the interface position nodes. The forward problem (the modelling of reflection
travel times) is solved using the finite-difference solver of Podvine & Lecomte
(1991) and using an a priori known background velocity model. This non-linear
method allows the automated determination of the global minimum (or maximum)
without relying on estimates of the gradient of the objective function in
the starting model and without making assumptions about the nature of the
objective function itself. We have used two types of objective functions. The
first is a least-squares L2 norm, defined as the sum of the squared differences between the observed and the calculated travel times. The second is based on
coherence measures (semblance). The main advantage of using coherence
measures is that they do not require travel-time picking to assess the degree of
fit to the data model. Thus, the time performance of the whole procedure is
improved and the subjectivity of the human operators in the picking procedure
is removed.
The methods are tested on synthetic models and have been applied to a subset
of data that was collected during the active seismic experiments performed in
September 2001 in the gulfs of Naples and Pozzuoli in the framework of what
is known as the SERAPIS project.
crust seismic reflectors. The techniques are based on migration and waveform
coherence analysis of reflected seismic phases recorded in local earthquake seismograms
and in active seismic data.
The first method is a move-out and stack of reflected seismic phases in local
earthquake recordings. The theoretical travel times of reflected/converted
phases in a 1D medium for a given interface depth and velocity model are used
to align the recordings in time. The locations and origin times of events are initially
estimated from the P and S arrival times. Different seismic gathers are
obtained for each reflected/converted phase at the interface under consideration,
and the best interface depth is chosen as that which maximizes the value
of a semblance function computed on moved-out records. This method has
been applied to seismic records of microearthquakes that have occurred at the
Mt. Vesuvius volcano, and it confirms the reports of an 8- to 10-km-deep seismic
discontinuity beneath the volcano that was previously identified as the
roof of an extended magmatic sill.
The second is a non-linear 2D method for the inversion of reflection travel
times aimed at the imaging of a target upper-crust reflector. This method is specifically
designed for geophysical investigations in complex geological environments
(oil investigations, retrieving of images of volcano structures) where the
presence of complex structures makes the standard velocity analysis difficult
and degrades the quality of migrated images. Our reflector is represented by
nodes of a cubic-spline that are equally spaced at fixed horizontal locations. The
method is based on a multiscale approach and uses a global optimization technique
(genetic algorithm) that explores the whole of the parameter space, i.e.
the interface position nodes. The forward problem (the modelling of reflection
travel times) is solved using the finite-difference solver of Podvine & Lecomte
(1991) and using an a priori known background velocity model. This non-linear
method allows the automated determination of the global minimum (or maximum)
without relying on estimates of the gradient of the objective function in
the starting model and without making assumptions about the nature of the
objective function itself. We have used two types of objective functions. The
first is a least-squares L2 norm, defined as the sum of the squared differences between the observed and the calculated travel times. The second is based on
coherence measures (semblance). The main advantage of using coherence
measures is that they do not require travel-time picking to assess the degree of
fit to the data model. Thus, the time performance of the whole procedure is
improved and the subjectivity of the human operators in the picking procedure
is removed.
The methods are tested on synthetic models and have been applied to a subset
of data that was collected during the active seismic experiments performed in
September 2001 in the gulfs of Naples and Pozzuoli in the framework of what
is known as the SERAPIS project.
References
Amand P., Virieux J. (1995). Non linear inversion of synthetic seismic reflection data by
simulated annealing. 65th Ann. Internat. Mtg: Soc. Expl. Geophy. Expanded Abstracts, 612-5.
Auger E., Gasparini P., Virieux J., Zollo A. (2001). Imaging of a mid-crust high to low
seismic discontinuity beneath Mt. Vesuvius. Science, 204, 1510-2.
Al-Yahya K. (1989). Velocity analysis by iterative profile migration. Geophysics, 54, 718-29.
Balch R. S., Hartse H. E., Sanford A., Lin K. (1997). A new map of the geographic extent
of the Socorro mid-crustal magma body. Bull. Soc. Seism. Am., 87, 174-82.
Bernard M.-L., Zamora M. (2000). Mechanical properties of volcanic rocks and their relations
to transport properties. EOS, Trans. Am. Geophys. U., 81, Fall Meet. Suppl.,
Abstract V71A-33.
Boschetti F., Dentith M. C., List R. D. (1996). Inversion of seismic refraction data using
genetic algorithms. Geophysics, 61, 1715-27.
Coutant O. (1989). Programme de simulation numerique AXITRA. Res. Report LGIT,
Grenoble.
Gasparini P., Tomoves Working Group (1998). Looking inside Mount Vesuvius. EOS,
Trans. Am. Geophys. U., 79, 229-32.
Goldberg X. (1989). Genetic Algoritm in Search, Optimization and Machine Learning.
Addison-Wesley Pub. Co., pp. 432.
Improta L., Zollo A., Herrero A., Frattini R., Virieux J., Dell’Aversana P. (2002). Seismic
imaging of complex structures by nonlinear traveltime inversion of dense wide-angle
data: application to a thrust belt. Geophys. J. Int., 151, 264-8.
Iyer H. M. (1992). Seismological detection and delineation of magma chambers:Present
status with emphasis on the Western USA, in Volcanic Seismology, edited by P. Gasparini,
R. Scarpa, K. Aki, Springer-Verlag, pp. 299-338.
Iyer H. M., Evans J. R., Dawson P. B., Stauber D. A., Achauer U. (1990). Differences in
magma storage in different volcanic environments as revealed by seismic tomography:
silicic volcanic centers and subduction-related volcanoes, in Magma transport and storage
edited by M.P. Ryan, Wiley, pp. 293-316.
James D., Clarke T., Meyer R. (1987). A study of seismic reflection imaging using
microearthquake sources, Tectonoph., 140, 65-79.
Lomax A., Zollo A., Capuano P., Virieux J. (2001). Precise, absoute earthquake location
under Somma-Vesuvius volcano using a new 3D velocity model. Geophys. J. Int., 146,
313-31.
Lomax A., Virieux J., Volantand P., Berge C. (2000). Probabilistic earthquake location in
3D and layered models: Introduction to a Metropolis-Gibbs method and comparison
with linear locations, in Advances in seismic event location, edited by C.H. Thurber, N.
Rabinowitz, Kluwer, Amsterdam, pp. 101-134.
Matsumoto S., Hasegawa A. (1996). Distinct S wave reflector in the midcrust beneath
Nikko-Shirane volcano in the northeastern Japan arc. J. Geoph. Res., 101, 3067-83.
Naess O. E., Bruland L. (1985). Stacking methods other than simle summation, in
Developments in Geophysical Methods, 6, 189-223, edited by A.A. Fitch, Elsevier Applied
Science Publishers, London.
Neidell N. S., Taner M. S. (1971). Semblance and other coherency measurements for multichannel
data. Geophysics, 36, 482-97.
Nisii V., Zollo A., Iannaccone G. (2003). Depth of a mid-crustal discontinuity beneath
Mt Vesuvius from the stacking of reflected and converted waves on local earthquake
records. Bull. Soc. Seism. Am., 94(5), 1842-9.
Podvin P., Lecomte I. (1991). Finite difference computation of traveltimes in very contrasted
velocity models: a massively parallel approach and its associated tools. Geophys.
J. Int., 105, 271-84.
Ryan M. P. (1994). Neutral-Buoyancy Controlled Magma Transport and Storage in Midocean
Ridge Magma Reservoirs and Their Sheeted-Dike Complex: A Summary of
Basic Relationships. in Magmatic Systems, vol. 2, edited by M.P. Ryan, Academic Press,
London, pp. 97-138.
Rinehart E., Sanford A. R. (1981). Upper crustal structure of the Rio Grande Rift near
Socorro, New Mexico, from inversion of microearthquake S-wave reflections. Bull. Soc.
Seism. Am., 71, 437-50.
Toldi J. L. (1989). Velocity analysis without picking. Geophysics, 34, 191-9.
Sambridge M., Drijkoningen G. (1992). Genetic algorithms in seismic waveform inversion.
Geophys. J. Int., 109, 323-42.
Sanders C. O. (1984). Location and configuration of magma bodies beneath Long Valley,
California, determined from anomalous earthquake signals. J. Geophys. Res., 89, 8287-
302.
Sanford A. R., Alptekinand O., Toppozada T. R. (1973). Use of reflection phases on
microearthquake seismograms to map an unusual discontinuity beneath the Rio Grande
Rift. Bull. Seism. Soc. Am., 63, 2021-34.
Sheriff R. E., Geldart L. P. (1982). Exploration Seismology. Cambridge University Press, New
York.
Stroujkova A. F., Malin P. E. (2000). A magma mass beneath Casa Diablo? Further evidence
from reflected seismic waves. Bull. Seism. Soc. Am., 90, 500-11.
Yilmaz O. (1987). Seismic Data Processing, in Investigations in Geophysics, edited by B.
Nictzel, Vol. 2, Society of Exploration Geophysicists, Tulsa, Oklahoma.
Yilmaz O., Chambers R. (1984). Migration velocity analisis by wavefield extrapolation.
Geophys., 49, 1664-74.
Zollo A., Gasparini P., Virieux J., Le Meur H., De Natale G., Biella G., Boschi E.,
Capuano P., de Franco R., Dell’Aversana P., De Matteis R., Guerra I., Iannaccone G.,
Mirabile L., Vilardo G. (1996). Seismic evidence for a low-velocity zone in the upper
crust beneath Mount Vesuvius. Science, 274, 592-4.
Zollo A., D’Auria L., De Matteis R., Herrero A., Virieux J., Gasparini P. (2002). Bayesian
estimation of 2D P-velocity models from active seismic arrival time data: Imaging of
the shallow structure of Mt. Vesuvius (Southern Italy). Geophys. J. Int., 151, 556-82.
Zollo A., Marzocchi W., Capuano P., Lomax A., Iannaccone G. (2002). Space and time
behaviour of seismic activity al Mt. Vesuvius volcano, Southern Italy. Bull. Seism. Soc.
Am., 92(2), 625-40, doi: 10.1785/0120000287.
simulated annealing. 65th Ann. Internat. Mtg: Soc. Expl. Geophy. Expanded Abstracts, 612-5.
Auger E., Gasparini P., Virieux J., Zollo A. (2001). Imaging of a mid-crust high to low
seismic discontinuity beneath Mt. Vesuvius. Science, 204, 1510-2.
Al-Yahya K. (1989). Velocity analysis by iterative profile migration. Geophysics, 54, 718-29.
Balch R. S., Hartse H. E., Sanford A., Lin K. (1997). A new map of the geographic extent
of the Socorro mid-crustal magma body. Bull. Soc. Seism. Am., 87, 174-82.
Bernard M.-L., Zamora M. (2000). Mechanical properties of volcanic rocks and their relations
to transport properties. EOS, Trans. Am. Geophys. U., 81, Fall Meet. Suppl.,
Abstract V71A-33.
Boschetti F., Dentith M. C., List R. D. (1996). Inversion of seismic refraction data using
genetic algorithms. Geophysics, 61, 1715-27.
Coutant O. (1989). Programme de simulation numerique AXITRA. Res. Report LGIT,
Grenoble.
Gasparini P., Tomoves Working Group (1998). Looking inside Mount Vesuvius. EOS,
Trans. Am. Geophys. U., 79, 229-32.
Goldberg X. (1989). Genetic Algoritm in Search, Optimization and Machine Learning.
Addison-Wesley Pub. Co., pp. 432.
Improta L., Zollo A., Herrero A., Frattini R., Virieux J., Dell’Aversana P. (2002). Seismic
imaging of complex structures by nonlinear traveltime inversion of dense wide-angle
data: application to a thrust belt. Geophys. J. Int., 151, 264-8.
Iyer H. M. (1992). Seismological detection and delineation of magma chambers:Present
status with emphasis on the Western USA, in Volcanic Seismology, edited by P. Gasparini,
R. Scarpa, K. Aki, Springer-Verlag, pp. 299-338.
Iyer H. M., Evans J. R., Dawson P. B., Stauber D. A., Achauer U. (1990). Differences in
magma storage in different volcanic environments as revealed by seismic tomography:
silicic volcanic centers and subduction-related volcanoes, in Magma transport and storage
edited by M.P. Ryan, Wiley, pp. 293-316.
James D., Clarke T., Meyer R. (1987). A study of seismic reflection imaging using
microearthquake sources, Tectonoph., 140, 65-79.
Lomax A., Zollo A., Capuano P., Virieux J. (2001). Precise, absoute earthquake location
under Somma-Vesuvius volcano using a new 3D velocity model. Geophys. J. Int., 146,
313-31.
Lomax A., Virieux J., Volantand P., Berge C. (2000). Probabilistic earthquake location in
3D and layered models: Introduction to a Metropolis-Gibbs method and comparison
with linear locations, in Advances in seismic event location, edited by C.H. Thurber, N.
Rabinowitz, Kluwer, Amsterdam, pp. 101-134.
Matsumoto S., Hasegawa A. (1996). Distinct S wave reflector in the midcrust beneath
Nikko-Shirane volcano in the northeastern Japan arc. J. Geoph. Res., 101, 3067-83.
Naess O. E., Bruland L. (1985). Stacking methods other than simle summation, in
Developments in Geophysical Methods, 6, 189-223, edited by A.A. Fitch, Elsevier Applied
Science Publishers, London.
Neidell N. S., Taner M. S. (1971). Semblance and other coherency measurements for multichannel
data. Geophysics, 36, 482-97.
Nisii V., Zollo A., Iannaccone G. (2003). Depth of a mid-crustal discontinuity beneath
Mt Vesuvius from the stacking of reflected and converted waves on local earthquake
records. Bull. Soc. Seism. Am., 94(5), 1842-9.
Podvin P., Lecomte I. (1991). Finite difference computation of traveltimes in very contrasted
velocity models: a massively parallel approach and its associated tools. Geophys.
J. Int., 105, 271-84.
Ryan M. P. (1994). Neutral-Buoyancy Controlled Magma Transport and Storage in Midocean
Ridge Magma Reservoirs and Their Sheeted-Dike Complex: A Summary of
Basic Relationships. in Magmatic Systems, vol. 2, edited by M.P. Ryan, Academic Press,
London, pp. 97-138.
Rinehart E., Sanford A. R. (1981). Upper crustal structure of the Rio Grande Rift near
Socorro, New Mexico, from inversion of microearthquake S-wave reflections. Bull. Soc.
Seism. Am., 71, 437-50.
Toldi J. L. (1989). Velocity analysis without picking. Geophysics, 34, 191-9.
Sambridge M., Drijkoningen G. (1992). Genetic algorithms in seismic waveform inversion.
Geophys. J. Int., 109, 323-42.
Sanders C. O. (1984). Location and configuration of magma bodies beneath Long Valley,
California, determined from anomalous earthquake signals. J. Geophys. Res., 89, 8287-
302.
Sanford A. R., Alptekinand O., Toppozada T. R. (1973). Use of reflection phases on
microearthquake seismograms to map an unusual discontinuity beneath the Rio Grande
Rift. Bull. Seism. Soc. Am., 63, 2021-34.
Sheriff R. E., Geldart L. P. (1982). Exploration Seismology. Cambridge University Press, New
York.
Stroujkova A. F., Malin P. E. (2000). A magma mass beneath Casa Diablo? Further evidence
from reflected seismic waves. Bull. Seism. Soc. Am., 90, 500-11.
Yilmaz O. (1987). Seismic Data Processing, in Investigations in Geophysics, edited by B.
Nictzel, Vol. 2, Society of Exploration Geophysicists, Tulsa, Oklahoma.
Yilmaz O., Chambers R. (1984). Migration velocity analisis by wavefield extrapolation.
Geophys., 49, 1664-74.
Zollo A., Gasparini P., Virieux J., Le Meur H., De Natale G., Biella G., Boschi E.,
Capuano P., de Franco R., Dell’Aversana P., De Matteis R., Guerra I., Iannaccone G.,
Mirabile L., Vilardo G. (1996). Seismic evidence for a low-velocity zone in the upper
crust beneath Mount Vesuvius. Science, 274, 592-4.
Zollo A., D’Auria L., De Matteis R., Herrero A., Virieux J., Gasparini P. (2002). Bayesian
estimation of 2D P-velocity models from active seismic arrival time data: Imaging of
the shallow structure of Mt. Vesuvius (Southern Italy). Geophys. J. Int., 151, 556-82.
Zollo A., Marzocchi W., Capuano P., Lomax A., Iannaccone G. (2002). Space and time
behaviour of seismic activity al Mt. Vesuvius volcano, Southern Italy. Bull. Seism. Soc.
Am., 92(2), 625-40, doi: 10.1785/0120000287.
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