Seismic Threat Level Heightened
April 10, 2011 • 5:51PM

A further examination of the record of earthquakes and volcanoes for the past century shows a greater increase in the threat level from large seismic and volcanic activity, beginning at the time of the year 2000 solar maximum, than previously calculated.

If you take the lower threshold as magnitude 7.9, instead of 8.0, the increase in seismic and volcanic activity turns out to be dramatically worse than the already dramatic one we presented earlier this week on It turns out that there were five 7.9 earthquakes in the decade 2000-2009, but no more than two in any previous decade. That brings the total quakes and volcanoes to 28 for the decade, not the 23 you get at the 8.0 threshold (the total for the 90s is 14). The differential increase in earthquake activity alone, is even more magnified, as the total earthquakes (magnitude 7.9+) for the decade come to 18 compared to a maximum of 12 in any decade of the previous century.

The lowering of the threshold magnitude by 0.1 is perfectly valid as a statistical measure. So long as the standard of comparison remains the same for all decades, the trend is better shown by inclusion of the 7.9 magnitude earthquakes, than by exclusion. It also turns out that some of the 7.9 earthquakes have later been upgraded to 8.0. In the case of the 2008 Sichuan, China earthquake, which alerted me to re-look at this data, it measured 8.0 on the Richter scale, and 7.9 on the moment magnitude scale. The government of China uses the Richter rating, while the USGS uses the moment magnitude scale.

The difference in scale use is not the key point to be argued, however. So long as it is applied consistently, there is no error in employing the moment magnitude scale, and some advantages to be gained, to my best knowledge. Rather, the point emphasized in Thursday's video ought to remain the focus, in respect to that question that the serious threat evident in the pattern of sharply increased great earthquake and volcanic activity over the 2000-2009 decade is obscured by a willfully fraudulent presentation of the data.