The British Geological Survey (BGS) recorded an earthquake with a magnitude of 5.2 (ML) on the Richter scale near Market Rasen, Lincolnshire at 00:56 GMT. The BGS has been inundated with calls from the public, media and emergency services throughout England.

Summary

DATE : 27 February 2008
ORIGIN TIME : 00:56 47.8s UTC
LAT/LONG : 53.404 ° North / 0.331 ° West
DEPTH : 18.6 km
MAGNITUDE : 5.2 ML
LOCALITY : Market, Rasen, Lincolnshire
INTENSITY: 6 EMS

The epicentre is approximately 4 km north of Market Rasen and reports suggest that the earthquake has been felt widely across England, with reports of damage to chimneys in the epicentral area. Earthquakes of this size occur in the mainland UK roughly every 30 years, although are more common in offshore areas. This is the largest earthquake in the UK since the magnitude 5.4 ML Lleyn Peninsula earthquake in 1984, which was widely felt across England and Wales. Earthquakes of this size are typically followed by aftershocks, but these are likely to be smaller the main shock. The largest aftershock recorded so far has a magnitude of 2.2 ML (Richter scale). BGS are currently deploying temporary instruments in the epicentral area to better understand aftershock activity.

UK Seismicity

Aftershocks

Above: These seismograms show a record of ground displacement as a function of time at a number of different BGS seismograph stations across the UK. The traces are ordered in increasing distance from the epicenter. The closest station, CWF, is 90 km from the epicentre. Amplitudes are scaled by ground displacement, measured in nanometers (nm). One nanometer is one millionth of a millimeter, so the maximum displacement at the closest station is just under 1 mm. (click here to view as larger image).

Macroseismic Survey

The preliminary isoseismal map is based on 1609 questionnaire responses received in the period of the first twelve hours after the earthquake. It also includes some information from other sources. It is highly provisional and subject to change.

At this stage it appears that the intensity distribution is somewhat irregular. There is no clear concentration of high intensities near the epicentre. Over an area bounded roughly by Liverpool, London and York, data have been fairly evenly spread. From many locations, too few locations have yet been received to determine intensity values. Where intensity values can be assigned, there seem to be pockets of higher intensity without a great deal of distinction due to distance. For this reason the isoseismals drawn here have a high degree of interpretation.

Outside this area, the density of replies drops sharply (partly this is a population distribution effect). Intensity 2 observations are noted from several locations in Ireland, from Edinburgh and Aberdeen, and it is rumoured, from the Netherlands.

As regards the highest intensities, there is no clear evidence for intensity 6 EMS either from the questionnaires or from field observation. The pattern of observations suggests a relatively deep focus.

Above: Macroseismic map showing the EMS Intensities for the Market Rasen earthquake of 27 February 2008, following the processing of 20,000 completed questionnaires received via the BGS website by 12:30 UTC on 3 March. Click here to view the above map in higher resolution.

OR

Click here to view the real-time "Shake Map" for the Market Rasen earthquake produced from our online questionnaire. The map shows the general distribution of intensities for the earthquake.

Did You Feel The Market Rasen Earthquake? Click here to complete a questionnaire.

Damage

These photographs were taken by a BGS team in Gainsborough on Wednesday 27 February 2008. Damage was mostly to the tops of a few chimneys on Victorian terraces and there was secondary damage to roofs caused by falling bricks. Note that damage was not just confined to Gainsborough and was observed in many other places.

Focal Mechanism

Above: Fault plane solution obtained from moment tensor solution using regional long-period waveform data for a source depth of 10 km. The solution shows predominantly strike-slip faulting on an either nearly EW or NS striking plane, which is consistent with maximum compression in NW-SE direction. The moment magnitude of 4.4 is smaller than the ML value of 5.2. This discrepancy has been observed for other UK earthquakes (e.g., Dudley 2002; Folkestone 2007). The moment magnitude scale reflects the physical dimension of the earthquake and the slip during the event. The match between observed and calculated seismograms was slightly worse for a source depth of 20 km, but the mechanism obtained was not very different.

News Websites Reporting on the Market Rasen Earthquake:

Issued 29 February 2008