Friday Headlines, August 31, 2018
THE LATEST IN THE GEOSCIENCES
This week in geology
- How old is an asteroid?
- Injecting waste water causes earthquakes
This week in the environment
- Looking at plants of the past to predict plants of the future
Particles collected by Hayabusa give absolute age of asteroid Itokawa
In 2003, the Japan Aerospace Exploration Agency (JAXA) launched the probe Hayabusa (which means “peregrine falcon”) to rendezvous with a near-Earth asteroid named Itokawa. In 2005, Hayabusa reached Itokawa, observed it from orbit then landed on the surface to collect rock samples. Hayabusa returned to earth with the rock samples in 2010.
Since then, scientists have been studying the rock to better understand the history of the asteroid.
Using these rock samples, it was determined that materials that make up Itokawa formed about 4.6 billion years ago, along with our entire solar system. About 1.5 billion years ago, a collision with another asteroid occurred, breaking up the original asteroid and resulting in the formation of today’s Itokawa.
More reading (may be paywalled): Thermal and impact histories of 25143 Itokawa recorded in Hayabusa particles
Injection wells can induce earthquakes miles away from the well
Many processes used to extract oil and gas from rock result in a great deal of waste water, which is not safe to simply dump on the Earth’s surface. One way to get rid of this water is to pump it back into the ground, below the reach of water used for human consumption. Where this water is pumped into the ground is called an injection well.
The pressure in the rock due to injecting the waste water has been known to cause small earthquakes. These earthquakes can be felt as far as 6 miles (10 kilometers) from the well site.
Additionally, scientists have learned that the kind of rock into which the water is injected affects the strength of these earthquakes and how far away they are felt. Earthquakes due to injection into sedimentary rocks appears to result in larger earthquakes that are felt further away from the well than those caused by injection into igneous or metamorphic rocks.
More reading (may be paywalled): The spatial footprint of injection wells in a global compilation of induced earthquake sequences
Prehistoric changes in vegetation help predict future of Earth’s ecosystems
After the end of the last glaciation about 12,000 years ago, the Earth warmed rapidly and vegetation changed dramatically. Current trends in climate change may drive an equally large change. Scientists are studying the changes in plant life due to the recent de-glaciation to help better understand what may happen to vegetation should modern global warming continue.
The authors discovered the most dramatic changes in the mid-to-high latitudes of North America, Europe, and South America. Of 594 sites studied on all continents except Antarctica, 93 percent (553 sites) experienced large to moderate changes in vegetation.
Because modern warming is occurring at a much greater rate than that at the end of the last glaciation, the authors expect vegetation changes to be even more extreme than they were during de-glaciation.
More reading (may be paywalled): Past and future global transformation of terrestrial ecosystems under climate change