A mild tremor was reported in the district in the Vellarada-Amboori region late Tuesday night.
The tremor registered a magnitude of 1.9 on the Richter Scale at the Peechi observatory of the National Centre for Earth Science Studies (NCESS), an NCESS official said.
The tremor, which took place around 12 midnight, lasted just a few seconds and no damage was reported in the region, which lies in the eastern part of the southern district, the Thiruvananthapuram district administration and the Station House Officer, Vellarada police station, said.
Local residents alerted the district administration and the Kerala State Disaster Management Authority (KSDMA) about it.
NCESS and the District Geologist have been asked to look into the incident, the district administration said.