Friday Headlines, October 24, 2014
THE LATEST IN THE GEOSCIENCES
California is DOOMED
Deinocherus: Terrible Hands (Goofy Body)
Turbidites: Nature’s Seismometers
With modern technology, like GPS, it’s possible to track nearly imperceptible motions along fault lines. Given the history in the San Franscisco area for earthquakes along the San Andreas fault system, USGS scientists have used these devices to track the very small motions (as small as a mm per year) along several prominent fault traces.
These small movements on the surface, called creep, relate to great amounts of strain building up at depth. This strain, the researchers believe, could cause earthquakes with magnitudes as great as 7.1.
That’s scary news for the Bay area that was heavily damaged by the 6.9 magnitude Loma Prieta quake that happened 25 years ago.
50 years ago, a pair of large, fossilized, dinosaurian arms were found. These arms lacked a body. Based on these arms, paleontologists named a new species, Deinocheirus mirificus, meaning “terrible hand, which is unusual”.
This week, after 50 years of waiting, the body of Deinocheirus has finally been described.
Sadly, the rest of its body is not nearly so impressive as its arms. Deinocheirus is described as ‘something out of a bad sci-fi movie.’ It’s a goofy-looking mix of features that includes a humped back, a horse-like head, and perhaps a tuft of tail feathers.
Turbidites are unique sediment deposits that occur when there’s a landslide or mudflow underwater. After the slide, the sediments fall back down and collect on the bottom of the ocean or lake. As the sediments settle, the heavier (and coarser) things settle out first, followed by lighter and lighter sediments, resulting in a “fining-upward” sequence. Repeated underwater landslides result in repeated fining-upward sequences.
There are lots of things that can trigger turbidites. One of these is earthquakes.
In a lake in New Zealand, evidence for past earthquakes is hidden in the bottom sediments in the form or turbidite deposits. Using this evidence, plus radiometric dating of fossilized leaves in the sediment, scientists can assign ages to several earthquakes that happened in the region of the lake in the remote past and make predictions about future quakes.