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So if I'm understanding this correctly, he needs to make a new graph which starts from 1960 to ensure all magnitudes are cataloged? I think you would see the same curve. Or am I getting this totally wrong?
Originally posted by Phage
reply to post by tauristercus
Neat. Too bad the database you used doesn't seem to include them. Or should I say, the search doesn't find them. Probably has something to do with this:
For global events, magnitudes are not routinely reported until the early 1960s. This means, for example, that the largest earthquake observed - the 1960 Chilean earthquake (Mw 9.5) - appears in this catalog without an associated magnitude.
So an earthquake with no magnitude in the catalog will not be found in a search for a magnitude range of 6.0 - 6.9, will it? Why are you disregarding what ANSS says about its own database? It is the one you used, isn't it?
[edit on 4/13/2010 by Phage]
If you’ve been feeling more shaking this year, it’s not your imagination. The number of quakes greater than magnitude 4.0 in Southern California and Baja California has increased significantly in 2010. There have been 70 such quakes so far this year, the most of any year in the last decade. And it’s only April. There were 30 in 2009 and 29 in 2008. Seismologists said they are studying the uptick but cannot fully explain it.
Egill Hauksson, a geophysicist at Caltech, said the rate of quakes in the region is “probably ... picking up again” after a relative lull that lasted more than a decade. “What it means is that we are going to have more earthquakes than in the average year,” said Hauksson.
Earthquakes have been in the forefront of public consciousness this year after January’s devastating temblor in Haiti, which killed tens of thousands. It was followed weeks later by a destructive temblor in Chile. And then came the Mexicali quake, which was stronger than Haiti's although much less destructive. Hauksson said it’s easy to read too much into this year's quake uptick.
posted by Tauristicus
The year 1997 marked the one hundredth anniversary of the general deployment of standardized and calibrated seismographs. It started with nine seismograph stations in 1898 that were capable of detecting, locating and measuring earthquakes of magnitude 7.0 or larger (M 7.0) anywhere in the globe. As a result, major earthquakes have been monitored globally and continuously for more than 100 years. By 1931 there were 350 stations operating worldwide that were locating and measuring M 6.5 earthquakes globally. By the 1950s the system of seismographs could locate all M 6.0 events occurring globally.
Source: T. M. Tsapanos and P. W. Burton, "Seismic Hazard Evaluation for Specific Seismic Regions of the World," Tectonophysics 194 (1991): p. 154.
Originally posted by asala
Im hearring word that its just about to be upgraded to about a 7.1
Via the china earthquake networks...
Will update if more comes up.
Originally posted by patmac
Can oil in our Earth's crust act like a lubricant? Is this all due to us messing with nature's gears? Just curious. I haven't heard anyone mention that on here before. I have NO intent to derail. Also, condolences to any lost in this recent quake.
[edit on 13-4-2010 by patmac]