Inside View - Does global warming mean more frequent and severe earthquakes?

(From Reinsurance)

Every newspaper in the western world showed the human and material toll inflicted by the 7.6 Richter-scale earthquake that devastated Pakistan on 8 October 2005. But the 23 aftershocks that cruelly added to the region's torment barely made the inside pages. It is only now, after the dust has settled, that the importance of these aftershocks is becoming clearer to the reinsurance industry.

Aftershocks are a usual ingredient of earthquake behaviour, but these 23 in Pakistan included 13 with a magnitude over 5.5 as measured by the US Geological Society. Those are substantial earthquakes, rare as aftershocks in both their size and power, and big enough to shake the scientific community.

TV evangelists and Jehovah's Witnesses have been preaching for decades that Jesus predicted in the Olivet Discourse (Matthew 24:7) that an increase in the frequency and intensity of earthquakes would happen just prior to His return to earth. As early as 1969, Charles F Richter (the originator of the Richter Scale) refuted "with some amusement" the evidence presented by "certain religious groups". Others labelled the belief "ridiculous".

Science, via seismology, took its first giant step in 1897 with the invention of a calibrated seismograph, and today there are over 4000 seismographic stations around the world. All produce a great quantity of information - the sheer volume of data and the conflicting, self-serving graphs of the warring theorists mean making sense of the numbers is problematic.

A question of authority

Although the consortium of seismological institutions have standards by which seismograms are supposed to provide 'authoritative' estimates, problems continue to exist. According to the Seismological Society of America, the strength of earthquake surface waves measured by Japanese and American seismologists usually diverges by 0.2 in magnitude. And any accurate historical study of earthquakes is hindered by incomplete records. Catalogues of events measuring 6.5 or less are especially unreliable for the early part of the 20th century.