FIRST AMENDMENT TO LOAN AGREEMENT

Exhibit 10.2

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this “Amendment”) is entered into as of the 2^nd day of March, 2011, by and among OYO GEOSPACE CORPORATION, a Delaware corporation (“Borrower”), EACH OF THE DOMESTIC SUBSIDIARIES OF THE BORROWER identified on Schedule 1 hereto (collectively, “Guarantor”), and THE FROST NATIONAL BANK, a national banking association (“Lender”).

RECITALS

A. On March 2, 2011, Borrower, Guarantor and Lender entered into that certain Loan Agreement (together with all amendments, modifications and restatements, the “Loan Agreement”), concerning, among other things, the terms, conditions and covenants of those certain Loans (as defined in the Loan Agreement). The Loans are evidenced by that certain Revolving Promissory Note dated March 2, 2011 in the original principal amount of $25,000,000.00 executed by Borrower and payable to the order of Lender.

B. Borrower has requested and Lender has also agreed to modify certain covenants contained in the Loan Agreement and further amend the Loan Agreement as contained herein.

C. All capitalized terms not otherwise defined in this Amendment shall have the same meanings as are set forth in the Loan Agreement.

NOW, THEREFORE, for and in consideration of the premises and mutual covenants herein contained and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Borrower and Lender hereby agree as follows:

AGREEMENTS

1. Amendments.

(a) The following paragraph is added as Section 6.14 to the Loan Agreement:

Section 6.14. Lender as Principal Depository. To maintain with Lender the primary operating account of Borrower and its Domestic Subsidiaries, including maintaining with Lender all business, cash management, operating and administrative deposit accounts, subject to compliance with Borrower’s investment policy as in effect from time to time.

(b) Section 7.11 of the Loan Agreement is hereby deleted in its entirety.

2. No Other Amendment. Except as specifically modified or amended herein, all terms, provisions and requirements of the Loan Agreement shall remain as written.

3. Reaffirmation. Borrower hereby reaffirms all covenants, conditions, representations and warranties contained in the Loan Agreement, as amended by this Amendment.

4. Counterparts. This Amendment may be executed in counterpart originals, no one of which need contain the signature of all parties, but all of which together shall constitute one and the same instrument.

5. Governing Law. This Amendment and all other Loan Documents shall be governed by, and construed in accordance with, the laws of the State of Texas, excluding those laws relating to the resolution of conflicts between laws of different jurisdictions.

6. Headings. The headings preceding the text of the paragraphs of this Amendment have been inserted solely for convenience of reference and shall neither constitute a part of this Amendment nor affect its meaning, interpretation, or effect.

NOTICE TO COMPLY WITH STATE LAW

For the purpose of this Notice, the term “WRITTEN AGREEMENT” shall mean this Amendment, the Loan Agreement, and the other Loan Documents, together with each and every other document relating to and/or securing the Loans, regardless of the date of execution.

NOTICE OF FINAL AGREEMENT

THIS WRITTEN AGREEMENT REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

[Signatures on the following pages]

2

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed as of the date first above written.

Signature Page

to First Amendment to Loan Agreement

Signature Page

to First Amendment to Loan Agreement

SCHEDULE 1

TO

FIRST AMENDMENT TO LOAN AGREEMENT

Guarantors

Schedule 1

to First Amendment to Loan Agreement