<PAGE>
                                                                    EXHIBIT 10.1

                           NINTH AMENDMENT TO LOAN AND
                               SECURITY AGREEMENT

         This Ninth Amendment dated January 3, 2003 (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"; each capitalized term used but not defined
herein having the meaning given to it in the Loan Agreement)

                               W I T N E S S E T H

         WHEREAS, the Borrower and its subsidiaries that have guaranteed
Obligations under the Loan Agreement (the "Guarantors", and, with the Borrower,
collectively, the "Obligors" and individually, an "Obligor") require access to
additional funds to continue their operations; and

         WHEREAS, the Obligors have proposed to Foothill and EALP that Foothill
and EALP agree to amend or waive applicable provisions of the Loan Documents so
as to allow the Obligors to receive and retain collections on their Accounts,
which would otherwise be automatically paid to Foothill for application to
Advances; and

         WHEREAS, EALP has agreed to allow the Obligors to use such proceeds and
to implement such agreement by purchasing the Obligors' Obligations to Foothill
as provided under Loan Agreement ss. 9.5 (the "Obligations Purchase") on the
condition that (1) the Obligors execute the Acknowledgment and Release
contemplated in Loan Agreement ss. 9.5 and in the form of Exhibit A; (2) the
Obligors agree to pay EALP, as an Obligation, all amounts EALP was required to
pay and did pay to Foothill in excess of the Obligors' Obligations to Foothill
on the date of purchase, as set forth on Exhibit B and (3) the Guarantors
reaffirm their Obligations to EALP under the Continuing Guaranty by executing
the Reaffirmation of Continuing Guaranty attached as Exhibit C.

         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. Each Obligor agrees to execute the Acknowledgment and
Release attached as Exhibit A and to deliver the same to Foothill.

                  2. The Borrower agrees to pay EALP under the Loan Agreement,
and each Guarantor agrees to guaranty payment to EALP under its Guaranty, all
amounts paid by EALP to Foothill in connection with the Obligations Purchase to
the extent such amounts exceed the Obligations owing to Foothill by the
Obligors, including without limitation:

         (a)      the Early Termination Fee paid as required by Section 9.5
                  (whether or not such fee was payable at such time by the
                  Obligors) and




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         (b)      all other costs, expenses and fees paid to Foothill by EALP
                  (whether or not such costs, expenses and fees were at such
                  time payable by Obligors to Foothill)

all as set forth in the Schedule attached hereto as Exhibit B (the "Waiver
Fee"). As further evidence of their agreement to pay the Waiver Fee, the parties
hereto agree that the definition of "Obligations" in the Loan Agreement shall
be, and it hereby is, amended by the insertion immediately after the second
parenthetical therein, the words "Waiver Fee provided for under the Ninth
Amendment to the Agreement." The Guarantors agree that the term "Guaranteed
Obligations" as defined in the Guaranty is amended to include the Waiver Fee as
a Guaranteed Obligation.

                  3. Each of the Designated Subsidiaries hereby joins in this
Amendment for the purpose of consenting to the terms hereof. The Designated
Subsidiaries hereby agree that all terms, covenants and provisions of the Loan
Agreement and the other Loan Documents are, and shall remain, in full force and
effect, including (without limitation) the Designated Subsidiaries' guaranty of
the Obligations of the Borrower pursuant to the Subsidiary Guaranties, which
Subsidiary Guaranties are hereby acknowledged and reaffirmed with respect to all
Obligations of Borrower arising pursuant to the Loan Agreement and other Loan
Documents, as amended by this Amendment and all previous amendments.

                  4. 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. On the condition that the Obligors have fulfilled each and every one
of their obligations set forth in the preceding paragraphs 1-3, 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
                  midnight on January 24, 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 January 3, 2003, at any time after the
                  expiration of the Waiver Period; and

         (b)      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.



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                  5. This Amendment may be executed in one or more counterparts,
each of which when so executed shall be deemed to be an original, but all of
which when taken together shall constitute one and the same instrument. Each
Obligor may indicate its intention to be bound hereby executing its signature
page and delivering the same by facsimile to EALP or its counsel, and EALP may
indicate its intention to be bound by executing its signature page and
delivering the same to the Borrower or its counsel. The delivery of a party's
signature on the signature page by facsimile transmission shall have the same
force and effect as if such party signed and delivered this Amendment in person.

         IN WITNESS WHEREOF, this Amendment has been executed and delivered as
of January 3, 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/ Elliott Greenberg
                                       --------------------------------------
                                   Name:      Elliott 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
                              ------------------------------------





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<PAGE>
                            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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