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                                                                    EXHIBIT 10.1

                FOURTH SUPPLEMENT TO NINTH AMENDMENT TO LOAN AND
                               SECURITY AGREEMENT

                               W I T N E S S E T H

      WHEREAS, the Ninth Amendment (the "Amendment") to that certain Loan and
Security Agreement (as amended, the "Loan Agreement"), dated as of May 11, 1999,
as amended by Amendments Nos. 1-8, among Grant Geophysical, Inc. ("Borrower"),
Elliott Associates, L.P. ("EALP"), as a Lender, and Foothill Capital Corporation
("Foothill"), as Agent (the "Agent") and a Lender (and, together with EALP, the
"Lenders") was entered into by Borrower, EALP and Foothill on January 3, 2003;
each capitalized term used but not defined herein having the meaning given to it
in the Loan Agreement and the Ninth Amendment.

      WHEREAS, pursuant to the Supplement to Ninth Amendment to Loan and
Security Agreement, executed and delivered as of January 22, 2003, the Waiver
Period, as defined in the Ninth Amendment, was first extended through and
including February 5, 2003, again extended through and including February 21,
2003, and later extended through and including March 7, 2003.

      WHEREAS, Borrower and its subsidiaries and EALP desire that the Waiver
Period, as defined in the Ninth Amendment, be further extended to and including
March 14, 2003.

      NOW THEREFORE, the parties hereto, in consideration of the mutual promises
set forth herein (which are acknowledged to be good, valuable and sufficient
consideration), and each intending to be legally bound hereby, agree as follows:

            1. The Obligors agree, acknowledge and admit that the failure to
remit proceeds of Accounts to EALP as Agent and sole Lender constitutes an Event
of Default (the "Admitted Default") entitling EALP to accelerate all Obligations
immediately and to commence the exercise of remedies under the Loan Documents.
EALP as the successor Agent and sole Lender upon giving effect to the
Obligations Purchase,

      (a)   agrees that the Obligors may retain the proceeds of Accounts
            received by the Obligors (i) prior to and including January 3, 2003,
            if such proceeds have not been turned over, and (ii) from and
            excluding January 3, 2003 through and including 11:59 PM on March
            14, 2003 (the "Waiver Period"); provided, however, that nothing
            contained herein shall allow the Obligors to retain any proceeds of
            Accounts, whether received before, on or after March 14, 2003, at
            any time after the expiration of the Waiver Period;

      (b)   agrees that any payments due on account of the Obligations from and
            after January 24, 2003 to and including March 14, 2003 shall be due
            and payable on March 17, 2003; and

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      (c)   on the condition that no Default or Event of Default (other than the
            Admitted Default) has occurred, agrees for the duration of the
            Waiver Period not to (x) accelerate the Obligations or (y) exercise
            its remedies arising from the Admitted Default.

Nothing contained herein, however, shall constitute a waiver of any other rights
EALP has under the Loan Documents. Without limiting the generality of the
foregoing, EALP specifically reserves its right to enforce, and the Obligors
specifically reaffirm their obligation to comply with, all provisions of the
Loan Documents relating to the continued attachment and perfection of Liens
securing the Obligations on, in or with respect to all of the Collateral,
including without limitation the proceeds of the Accounts.

      IN WITNESS WHEREOF, this Fourth Supplement has been executed and delivered
as of March 7, 2003.

                                    ELLIOTT ASSOCIATES, L.P., a Delaware limited
                                    partnership,

                                    By: Elliott Capital Advisors, L.P.,
                                        as general partner

                                        By: Braxton Associates, Inc. as general
                                            partner

                                            By: /s/ PAUL SINGER
                                                --------------------------------
                                            Name:
                                            Title:


                                        GRANT GEOPHYSICAL, INC.,
                                        a Delaware corporation

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO


                                        ADVANCED SEISMIC TECHNOLOGY, INC., a
                                        Texas corporation

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO


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                                        GRANT GEOPHYSICAL CORP.,
                                        a Texas corporation

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO


                                        GRANT GEOPHYSICAL (INT'L) INC.,
                                        a Texas corporation

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO


                                        GRANT GEOPHYSICAL DO BRASIL LTDA., a
                                        corporation organized under the laws of
                                        the Republic of Brazil, South America

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO


                                        PT. GRANT GEOPHYSICAL INDONESIA,
                                        a corporation organized under the laws
                                        of the Republic of Indonesia

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO


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                                        SOLID STATE GEOPHYSICAL INC.,
                                        a corporation organized under the laws
                                        of the Province of Alberta, Canada

                                        By: /s/ RICHARD F. MILES
                                            ---------------------------------
                                        Name:   Richard F. Miles
                                        Title:  President and CEO



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