Detection Statistics

Larger earthquakes occur less frequently than smaller ones. The relationship is exponential, ie there are ten times as many magnitude 4 or larger earthquakes in a given time period than magnitude 5 or larger earthquakes. This can be expressed by the Gutenberg-Richter formula

where N is the number of earthquakes per year exceeding a given magnitude M. The constant a reflects the absolute level of seismicity in an area, and the value of b has generally been found to be consistently close to 1.0.

The graph shows the relationship for the UK. A least-squares regression to this data gives the relationship

Also shown is an alternative doubly-truncated exponential model which gives a curved fit ot the data at the higher magnitude end.

On average, the UK may expect:

• an earthquake of 3.7 ML or larger every 1 year
• an earthquake of 4.7 ML or larger every 10 years
• an earthquake of 5.6 ML or larger every 100 years.

• Real-time Data
• Detection Capability
• Detection Statistics
• Station Book

• Magnitude 4.6 ML Earthquake South Wales 17/02/2018
• The magnitude 4.6 ML Earthquake South Wales on 17/02/2018 recorded on the Vale of Pickering sesimic network
• M7.1 PUEBLA, MEXICO 19/09/2017
• M8.1 CHIAPAS PROVINCE, MEXICO 08/09/2017
• North Korea Nuclear Test 03/09/2017
• Baseline Monitoring in the Vale of Pickering
• Are yesterday's earthquakes tomorrow's disasters?
• Monitoring earthquakes: PlanetEarth podcast