Friday Headlines, March 21, 2014
THE LATEST IN THE GEOSCIENCES
A new gully on Mars
Water in the deep Earth
A big-ish earthquake in LA
The search for liquid water on Mars is a major focus for planetary scientists these days. Imagine their delight in seeing a new gully appear on the surface of Mars.
On Earth, new gullies form from the flow of water. On Mars, especially where this gully formed, temperatures are too cold for water to be liquid. It is more likely that flowing carbon dioxide is a more likely culprit.
This headline is a little misleading. No, there’s not a sea of liquid water deep in the Earth, a la “Journey to the Center of the Earth.”
However, minerals are capable of holding water within their crystal matrix. Temperatures and pressures deep within the Earth have been thought sufficient to drive such water out of crystals, resulting in the Earth being ‘dry’ at great depths.
Around 400 kilometers below the Earth’s surface is the so-called ‘transition zone,’ between upper and lower mantle. At this transition zone, there are a series of mineral changes due to temperature and pressure. One important change is from the mineral olivine to the mineral ringwoodite.
Recently, a specimen of ringwoodite was found on the Earth’s surface, driven there by volcanic activity. The surprize was to find that about 1.5 percent of the ringwoodite’s weight was made up of water. That might not seem like much, but if you consider the entire volume of the transition zone, it would add up to about the same amount of water as there is in all the world’s oceans combined.
There was an earthquake in California.
So what? you say. California has earthquakes all the time.
This one was among the largest that have it the metropolitan area in over 20 years. So, yeah, it was just another earthquake, but it caught the attention of a lot of people, including this news anchor:
Earthquakes rattle California all the time, because the Pacific Plate is sliding North past the North American plate along the San Andreas Fault.
Technically, this event has been called the Encino Earthquake, but since this one happened on St. Patrick’s day, some have informally dubbed it the Shamrock Shake.