<PAGE>
                                                                  EXHIBIT 10.1



                    SUPPLEMENT TO NINTH AMENDMENT TO LOAN AND
                               SECURITY AGREEMENT


                                   WITNESSETH

         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, Borrower and its subsidiaries and EALP desire that the Waiver
Period, as defined in the Ninth Amendment, be extended until February 5, 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 February
                  5, 2003, if such proceeds have not been turned over, and (ii)
                  from and excluding February 5, 2003 through and including
                  midnight on February 5, 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 February 5, 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 to and including February 5, 2003
                  shall be due and payable on February 5, 2003; and

         (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.



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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 Supplement has been executed and delivered as
of January 24, 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/ ELLIOT GREENBERG
                                                 ------------------------------
                                              Name:   Elliot Greenberg
                                                   ----------------------------
                                              Title:  Vice-President
                                                    ---------------------------

                                   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
                                                    ---------------------------

                                   GRANT GEOPHYSICAL CORP.,
                                   a Texas corporation

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



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                                   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
                                                    ---------------------------


                                   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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