Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Beresnev, I. A. Search for Related Content GeoRef GeoRef Citation

Uncertainties in Finite-Fault Slip Inversions: To What Extent to Believe? (A Critical Review)

Department of Geological and Atmospheric Sciences
Iowa State University, 253 Science I
Ames, Iowa 50011-3212
beresnev{at}iastate.edu

Manuscript received 6 November 2002.

The matrix inversion of seismic data for slip distribution on finite faults is based on the formulation of the representation theorem as a linear inverse problem. The way the problem is posed and parameterized involves substantial, and often subjective, decision making. This introduces several levels of uncertainty, some of them recognized and some not adequately addressed. First, the inverse problem must be numerically stabilized and geologically constrained to obtain meaningful solutions. It is known that geologically irrelevant solutions also exist that may even better fit the data. It is also known that obtaining a stabilized, constrained solution compatible with the data does not guarantee that it is close to the true slip. Second, once the scheme has been set up, there still remains significant uncertainty in seismological parameterization. Synthetic tests have consistently shown that incorrect assumptions about the parameters fixed in the inversions, such as the rupture speed, fault geometry, or crustal structure, generate geologic artifacts, which are also dependent on array geometry. Third, solving the inverse problem involves numerical approximation of a continuous integral, with the generally grid-dependent result. Fourth, maintaining a linear inverse problem requires that the final slip on each subfault be the only variable to solve for. The slip functions used in the inversions are typically integrals of triangles or boxcars; they all involve a second parameter, slip duration, which has to be fixed. The effect of chosen duration cannot be disregarded, especially when frequencies higher than 0.1-0.5 Hz in the data are modeled. Fifth, the spectra of triangles and boxcars are sinc functions, whose relevance to realistically observed spectra is problematic.

How close then could an inverted slip image be to the true one? There are reasons to believe that the fine structure resolved is often an artifact, dependent on the choice of a particular inversion scheme, variant of seismological parameterization, geometry of the array, or grid spacing. This point is well illustrated by examining the inversions independently obtained for large recent events, for example, the 1999 zmit, Turkey, earthquake. There is no basis currently available for distinguishing between artificial and real features. One should be cautioned against any dogmatic interpretation of inhomogeneous features on inverted slips, except their very gross characteristics.

This article has been cited by other articles:

				J. Salichon, A. Lemoine, and H. Aochi Validation of Teleseismic Inversion of the 2004 Mw 6.3 Les Saintes, Lesser Antilles, Earthquake by 3D Finite-Difference Forward Modeling Bulletin of the Seismological Society of America, December 1, 2009; 99(6): 3390 - 3401. [Abstract] [Full Text] [PDF]

				S. G. Song, A. Pitarka, and P. Somerville Exploring Spatial Coherence between Earthquake Source Parameters Bulletin of the Seismological Society of America, August 1, 2009; 99(4): 2564 - 2571. [Abstract] [Full Text] [PDF]

				N. A. Anil-Bayrak and I. A. Beresnev Fault Slip Velocities Inferred from the Spectra of Ground Motions Bulletin of the Seismological Society of America, April 1, 2009; 99(2A): 876 - 883. [Abstract] [Full Text] [PDF]

				K. Asano and T. Iwata Source Rupture Process of the 2004 Chuetsu, Mid-Niigata Prefecture, Japan, Earthquake Inferred from Waveform Inversion with Dense Strong-Motion Data Bulletin of the Seismological Society of America, February 1, 2009; 99(1): 123 - 140. [Abstract] [Full Text] [PDF]

				B. E. Shaw and S. G. Wesnousky Slip-Length Scaling in Large Earthquakes: The Role of Deep-Penetrating Slip below the Seismogenic Layer Bulletin of the Seismological Society of America, August 1, 2008; 98(4): 1633 - 1641. [Abstract] [Full Text] [PDF]

				G. Hillers and S. G. Wesnousky Scaling Relations of Strike-Slip Earthquakes with Different Slip-Rate-Dependent Properties at Depth Bulletin of the Seismological Society of America, June 1, 2008; 98(3): 1085 - 1101. [Abstract] [Full Text] [PDF]

				S. Lorito, A. Piatanesi, and A. Lomax Rupture Process of the 18 April 1906 California Earthquake from Near-Field Tsunami Waveform Inversion Bulletin of the Seismological Society of America, April 1, 2008; 98(2): 832 - 845. [Abstract] [Full Text] [PDF]

				G. C. P. King and S. G. Wesnousky Scaling of Fault Parameters for Continental Strike-Slip Earthquakes Bulletin of the Seismological Society of America, December 1, 2007; 97(6): 1833 - 1840. [Abstract] [Full Text] [PDF]

				E. Tinti, E. Fukuyama, A. Piatanesi, and M. Cocco A Kinematic Source-Time Function Compatible with Earthquake Dynamics Bulletin of the Seismological Society of America, August 1, 2005; 95(4): 1211 - 1223. [Abstract] [Full Text] [PDF]