Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Title of 12(b) Security	Common Stock
Trading Symbol	GEOS
Security Exchange Name	NASDAQ
Entity Registrant Name	GEOSPACE TECHNOLOGIES CORP
Entity Central Index Key	0001001115
Current Fiscal Year End Date	--09-30
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,664,989
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity File Number	001-13601
Entity Tax Identification Number	76-0447780
Entity Incorporation, State or Country Code	TX
Entity Address, Address Line One	7007 Pinemont
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77040
City Area Code	(713)
Local Phone Number	986-4444
Document Quarterly Report	true
Document Transition Report	false