On Tuesday 23 October, Cuadrilla Resources paused its fracking operations at its Preston New Road site after detecting a 0.4 magnitude seismic event.
This kind of tremor could not be felt on the surface, but is very close to the Oil and Gas Authority's limit for a 'red alert', whereby a company is required to stop fracking. The red alert is triggered when an event in excess of 0.5 magnitude is recorded.
This was the sixth seismic event recorded since fracking restarted on 13 October.