	June 30, 2020			December 31, 2019
Credit facility:
Principal outstanding	$	20,500		$	35,000
Unamortized debt issuance costs		(140	)		(205	)
Carrying amount		20,360			34,795

Senior loan facility:
Principal outstanding		29,000			29,000
Unamortized debt issuance costs		(626	)		(1,232	)
Carrying amount		28,374			27,768

6% senior secured convertible notes due 2023:
Principal outstanding		60,000			60,000
Unamortized debt discount and debt issuance costs		(11,922	)		(13,341	)
Carrying amount		48,078			46,659

Notes payable		15,522			9,974

Finance leases		—			350

Total debt		112,334			119,546
Current portion of long-term debt and finance leases		(102,621	)		(112,401	)
Total long-term debt and finance leases	$	9,713		$	7,145

We repaid $14.5 million of the amounts outstanding under our credit facility with the net proceeds received from the sale of certain seismic data and related assets in January 2020 (see Note 2).

In May 2020, we received the proceeds from an unsecured loan in the amount of $6.8 million pursuant to the Paycheck Protection Program (the “PPP”) under the recently enacted Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). The PPP loan matures in May 2022 and bears interest at a rate of 1.0% per annum. Principal and interest are payable monthly beginning seven months from the date of the PPP loan and may be prepaid at any time prior to maturity with no prepayment penalties.

Under the term of the CARES Act, PPP loan recipients can apply for and be granted forgiveness for all or a portion of the loan. Such forgiveness will be determined, subject to limitations, based on the use of loan proceeds for payment of payroll costs and any covered payments of mortgage interest, rent, and utilities. In the event the loan, or any portion thereof, is forgiven pursuant to the PPP, the amount forgiven is applied to outstanding principal, and we would record a gain on extinguishment for the amount forgiven when we are legally released from being the primary obligor. We intend to use the proceeds of the PPP loan to maintain payroll and make lease, rent and utility payments; however, there is no assurance that the PPP loan will be forgiven, in whole or in part.

The credit agreements and indentures for our credit facility, senior loan facility and 2023 Notes contain certain representations, warranties, covenants and other terms and conditions which are customary for agreements of these types. As discussed in Note 1, the report of our independent registered public accounting firm on our consolidated financial statements included in our Annual Report on Form 10–K for the year ended December 31, 2019 contains an explanatory paragraph raising substantial doubt about our ability to continue as a going concern, which results in events of default under the credit facility and the senior loan facility, and a cross default under the indenture governing the 2023 Notes. We have entered into forbearance agreements with respect to our credit facility, senior loan facility and 2023 Notes, whereby the holders of the indebtedness thereunder have agreed to refrain from exercising their rights and remedies with respect to these existing defaults and other events of default that have occurred and are continuing as further specified in the forbearance agreements until 5:00 p.m. (New York City time) on the earlier of (i) August 31, 2020 and (ii) the date the forbearance agreements otherwise terminate in accordance with their terms. We have also amended the indenture governing the 2023 Notes to, among other things, provide that a fundamental change resulting from the failure of our common stock to be listed or quoted on any of the NYSE American, The New York Stock Exchange, The NASDAQ Global Select Market, The NASDAQ Global Market, The NASDAQ Capital Market, the OTCQX Market or the OTCQB Market (or any of their respective successors) will not be deemed to have occurred as a result of such failure until the earlier of (i) August 31, 2020 or (ii) the termination date of the forbearance period set forth in the existing forbearance agreement with respect to the 2023 Notes. However, the long–term debt outstanding under the credit facility, senior loan facility and 2023 Notes has been reclassified as current portion of long–term debt in these unaudited condensed consolidated financial statements.