The role of crustal quartz in continental tectonism...
Gravity, surface heat flow and EarthScope seismic data are combined in a new tool for measuring the averaged abundance of quartz in the Earth's crust... And the results are surprising.
Slow fault slip after the 2004 M9.3 Sumatra- Andaman earthquake
The 2004 earthquake is the largest to occur since the dawn of GPS positioning. In the first two years post-event, GPS sites on the Andaman Islands continued to move upward and southwestward by up to half a meter. These motions serve to relax stress changes during the earthquake, but the mechanism is unclear: Poroelastic fluid movements, flow of hot rock deep in the Earth and continued fault slip at depth are all candidate processes. Large differences in motion at closely-spaced (10-30 km) sites however suggest that fault slip played a dominant role in the first two years. (Coming soon: Fault slip and viscoelastic flow also play about equal roles in transient deformation from the most recent two years of data, with fault slip slightly dominant!)
Slow opening of the Rio Grande Rift
The Rio Grande Rift in Colorado and New Mexico is often cited as the type-example of a "narrow" continental rift. Four years of continuous measurement at 26 GPS sites suggests that opening of the rift is occurring at rates of 1.5 to 2.5 millimeters per year, but comparison to regional GPS sites indicates that the strain is surprisingly broadly distributed (over more than 300 km width at 95% confidence). The eastern limit of rifting is unbounded by existing measurements, but total width may be 500 km or more. By comparison, the width of rifting across the eastern Basin-Range (a type example for a "wide" continental rift province) is only 120 km.
A thought: |
"Our future is being decided now in a struggle that pits two divergent rivers of intellect:
one that views truth as an objective reality, to be pursued through honest and open inquiry,
a second that views reality as a fluid, and truth as a football match in which the ball advances via advocacy.
But an ideology that neglects reality,
or relies on the manufacture of false doubt and obfuscation of the truth,
will collapse of its own corruption.
To which future do you belong?"
Afterthought: It is maddening that, in the 21st century, we are still arguing over whether markets should be entirely free or rationally regulated. Adam Smith, the so-called "father of free-market capitalism", knew the ovious answer to this question in the 1700s... as did any 19th century reader of Dickens.
Updated 10/Jun/2013 Tony Lowry