Mathematical techniques could help forecast earthquakes
By ANIFriday, December 3, 2010
WASHINGTON - Researchers have used mathematical techniques to find patterns when medium-large earthquakes happen, i.e. earthquakes greater than 4.4, on the Richter scale.
The research, conducted by Universidad Pablo de Olavide (UPO) and the Universidad de Sevilla (US), is based on the data compiled by the Instituto Geogr�fico Nacional on 4,017 earthquakes between 3 and 7 on the Richter scale that occurred on the Iberian Peninsula and in the surrounding waters between 1978 and 2007.
The scientists applied clustering techniques to the data, which allowed them to find similarities between them and discover patterns that will help to forecast earthquakes.
The team focused on the two seismogenic regions with the most data (The Alboran Sea and the Western Azores-Gibraltar fault region) analysing three attributes: the magnitude of the seismic movement, the time elapsed since the last earthquake and the change in a parameter called the b-value from one earthquake and the other. The b-value reflects the tectonics of the region under analysis.
A high b-value means earthquakes are predominantly small in size and, therefore, the land has a low level of resistance while a low value indicates that there are a relatively similar number of large and small seismic movements, which implies the land is more resistant.
“We have discovered the strong relationship between earthquakes and the parameter b-value, recording accuracy rates of more than 80percent,” said Antonio Morales Esteban.
“After the calculations had been performed, providing the circumstances and sequences we have determined to be forerunners occur, we obtain a significant success probability,” he added.
The technique summarises the forecasts in two factors: sensitivity (probability of an earthquake occurring after the patterns detected occur) and specificity (probability of an earthquake not occurring when no patterns have occurred).
The results reflect a sensitivity of 90 percent and specificity of 82.56 percent for the Alboran Sea region and 79.31 percent and 90.38 percent respectively for the seismogenic region of the Western Azores-Gibraltar Fault.
“The results are promising, although I doubt we will ever be able to say that we are capable of forecasting an earthquake 100 percent accurately,” Mart�nez Alvarez conceded.
The study will be published this month by the journal Expert Systems with Applications. (ANI)
