Exhibit 10.2

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this “Amendment”) is entered into as of
the 2nd 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.

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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

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

 

LENDER: THE FROST NATIONAL BANK, a national banking association By:  

/s/ Larry Hammonds

Name:   Larry Hammonds Title:   Marketing President BORROWER: OYO GEOSPACE
CORPORATION, a Delaware corporation By:  

/s/ Thomas T. McEntire

  Thomas T. McEntire, Chief Financial Officer and Secretary GUARANTORS: OYOG
OPERATIONS, LP GEOSPACE TECHNOLOGIES, LP OYO INSTRUMENTS, LP CONCORD
TECHNOLOGIES, LP GEOSPACE ENGINEERING RESOURCES INTERNATIONAL, LP By:   OYOG,
LLC, a Delaware limited liability company, its general partner   By:  

/s/ Thomas T. McEntire

    Thomas T. McEntire, Vice President, Chief Financial Officer and Secretary

 

Signature Page

to First Amendment to Loan Agreement

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GEOSPACE TECHNOLOGIES CORPORATION GEOSPACE FINANCE CORP. OYOG, LLC OYOG LIMITED
PARTNER, LLC By:  

/s/ Thomas T. McEntire

  Thomas T. McEntire, Vice President, Chief Financial Officer and Secretary of
each of the Guarantors named above

 

Signature Page

to First Amendment to Loan Agreement

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SCHEDULE 1

TO

FIRST AMENDMENT TO LOAN AGREEMENT

Guarantors

 

(1) OYOG Operations, LP, a Texas limited partnership

 

(2) Geospace Technologies, LP, a Texas limited partnership

 

(3) OYO Instruments, LP, a Texas limited partnership

 

(4) Geospace Engineering Resources International, LP, a Texas limited
partnership

 

(5) Concord Technologies, LP, a Texas limited partnership

 

(6) Geospace Technologies Corporation, a Delaware corporation

 

(7) Geospace Finance Corp., a Texas corporation

 

(8) OYOG, LLC, a Delaware limited liability company

 

(9) OYOG Limited Partner, LLC, a Texas limited liability company

 

Schedule 1

to First Amendment to Loan Agreement