A 1.0 magnitude tremor has been recorded at a fracking site in Lancashire - the second within a day.
The seismic event was recorded at about 22:20 BST on Monday at Preston New Road near Blackpool.
Cuadrilla said the event lasted "for a couple of seconds" and was "unlikely" to have been widely felt. Operations at the site remain suspended.
Fracking was stopped by The Oil and Gas Authority (OGA) after a 2.9 magnitude earthquake was reported earlier.
The OGA said operations would remain suspended while it gathered data on recent seismic events and then "considers carefully whether or not the hydraulic fracturing operations, mitigations and assumptions set out in the operator's plan continue to be appropriate to manage the risk of induced seismicity" at the site.
It added there was no fixed timeframe for the suspension.
At present, government guidelines state that if fracking induces quakes above 0.5 magnitude then all drilling must cease for 18 hours.
Drilling was previously suspended at the Preston New Road site in 2011 after earthquakes of 1.4 and 2.3 magnitude were recorded.
It resumed last October after campaigners failed to get an injunction preventing it.
A spokeswoman for Cuadrilla said fracking had not been carried out over the weekend.
She added that the well integrity had been verified and "remains unaffected".
What is fracking?
- Hydraulic fracturing, or fracking, is a technique to extract gas and oil from the earth
- Liquid is pumped underground at high pressure to fracture shale rock and release gas or oil within
- Applications have also been submitted by various firms in Yorkshire, Nottinghamshire and for a second site in Lancashire
- The Department for Business, Energy & Industrial Strategy says shale gas "has the potential to be a new domestic energy source"