Friday Headlines, March 29, 2013
THE LATEST IN THE GEOSCIENCES
OKLAHOMA EARTHQUAKE LINKED TO OIL EXTRACTION WASTEWATER
In November of 2011, there was a series of earthquakes near Oklahoma’s town of Prague. This series of earthquakes is particularly interesting because we don’t expect earthquakes to occur in the middle of continents.
It was later determined that the fault that moved was a 300 million-year-old fault (called the Wilzetta Fault) that formed when the modern continent of Africa collided with North America to form the supercontinent of Pangaea, during an event called the Alleghenian Orogeny.
There was a mountain range throughout modern-day Oklahoma and Texas called the Ancestral Rocky Mountains. These mountains are completely eroded away now.
The question was, why would this fault slip now?
It turns out that 18 years earlier, wastewater from oil drilling operations in the area was injected into the ground, as a means of disposing of it. A recent paper published in the journal Geology (paywalled, sorry) shows that the injection of this wastewater may have altered the stress field in the rocks, causing the fault to rupture. More importantly, the observation this rupture can happen 18 years after the injection raises concerns about risks involved with water injection, including injections related to hydraulic fracturing or ‘fracking.’
METEOR OVER MANHATTAN: EAST COAST FIREBALL SET INTERNET ABUZZ
Last Friday (March 22) a bright fireball was observed along the eastern seaboard of the United States. It was observed all the way from Virginia into New Hampshire.
Such events are actually not all that uncommon, but often happen during the day or over the ocean and unpopulated areas where they are not seen. This coming in the wake of the big fireball that exploded near Chelyabinsk in Russia, caused quite a stir. There was no explosion, damage, or injuries associated with this fireball.
NEW FOSSIL SPECIES FROM A FISH-EAT-FISH WORLD WHEN LIMED ANIMALS EVOLVED
Several years ago a new species of lobe-finned fish called Tiktaalik roseae was discovered and described from Ellesmere Island in the Canadian Arctic. Tiktaalik is considered the closest fish ancestor that we know of to fully-land-dwelling amphibians. Its fins contain nearly all the bones that form limbs in land-dwelling animals, missing only the fingers and toes.
A new species of lobe-finned fish has also been found and now described from the same locality. It’s called Holoptychius bergmanni and, like Tiktaalik, was a predatory fish that lived in rivers and streams. It probably competed with Tiktaalik a bit, but likely preferred slightly deeper water.
Penny Higgins - Storyteller • Artist • Scientist 