Taxonomy term

geology

Impact signature in rock produced by lightning strikes

When a meteorite smashes into Earth’s rocky surface, the immense temperatures and pressures created can melt rock into glass and leave signatures of the impact behind. Impacts produce tell-tale planar features in quartz grains called shock lamellae — picture a scrambled television signal, with repeating horizontal lines chopping and distorting the image into layers — that scientists have thought were produced only by meteorites.

05 Jan 2018

In feats of tectonic strength, grain size matters

Plate tectonics involves some of the most powerful forces on Earth, but the lithosphere, of which the plates are made, is not infinitely strong: Weaknesses in the lithosphere allow it to break apart and form plate boundaries. Determining the strength of tectonic plates based on field observations has proved tricky, however, due to the sheer scale of plates, while experiments and calculations in the lab on olivine — the main mineral that makes up the lithosphere — have depicted plates as misleadingly strong. In a new lab-based study, researchers have taken a novel approach to testing olivine’s strength, and the results fit existing models of plate tectonics better than previous efforts.

04 Jan 2018

From space to village: NASA's SERVIR program brings a big picture to local communities

Established in 2005, the joint NASA and U.S. Agency for International Development program SERVIR (named for the Spanish verb “to serve”) puts geospatial satellite images and analysis tools into the hands of local decision-makers around the world to help them deal with natural disasters and plan for changing climates. 
02 Jan 2018

In the lab, machine learning improves quake forecasts

The U.S. Geological Survey estimates that about 500,000 detectable earthquakes occur worldwide every year. But accurate forecasts of when quakes will occur have long been out of reach, in large part because of the complexities of fault behavior.

29 Dec 2017

Driftwood reveals ancient Arctic currents and sea-ice levels

Arctic driftwood up to 12,000 years old is giving scientists a better understanding of how ocean currents and sea ice in the far north have changed through the Holocene. In a new study, published in the Journal of Geophysical Research: Oceans, scientists at the University of Oxford in England studied more than 900 pieces of driftwood collected from Arctic shorelines since the 1950s to investigate how shifting Arctic Ocean currents help melt or fortify sea ice.

28 Dec 2017

Turkey DNA reveals Mesa Verde denizens moved to New Mexico

The Mesa Verde region of southern Colorado was home to as many as 30,000 Puebloans through the middle of the 13th century, until severe drought drove them south into New Mexico, ending the cliff dwellers’ reign. In a new study, researchers have charted this mass migration using mitochondrial DNA from a novel source: turkey bones from the domesticated birds kept by Puebloans in both Mesa Verde and northern New Mexico.

28 Dec 2017

Nautical charts reveal coral decline around Florida Keys

Coral reef cover is known to have decreased over the past few decades, but longer term estimates of coral cover have been difficult to reconstruct. In a new study, researchers used high-resolution historical nautical maps from the 18th century to determine changes to reefs in the Florida Keys.

26 Dec 2017

Volcanism spiked global temps during past hothouse

Roughly 56 million years ago, global temperatures rose 5 degrees Celsius within a few thousand years in an event called the Paleocene-Eocene Thermal Maximum (PETM). Scientists have often attributed the relatively rapid warming of the PETM — frequently used as an analogue for understanding modern warming trends — to large-scale biogenic methane emissions from seafloor reservoirs. But in a new study, researchers tracking carbon and boron isotopes preserved in the shells of tiny marine creatures called foraminifera, or forams, question the conventional wisdom, instead pointing to a volcanic source for the carbon emitted during the PETM.

25 Dec 2017

Earthquakes shaped ancient Greek culture

In ancient Greece, earthquakes frequently shook the ground and devastated cities and temples. But time after time, people built — and rebuilt — prominent structures near dangerous faults. How much the ancient Greeks knew about earthquakes and fault behavior is unclear. But in a new study in Proceedings of the Geologists’ Association, researchers suggest that the relationship between sacred sanctuaries and faults is more than coincidental, and that earthquakes may have had a previously underappreciated cultural significance to the ancient civilization.

22 Dec 2017

New Zealand quake triggers two large slow-slip events

On Nov. 14, 2016, a magnitude-7.8 earthquake struck near Kaikoura on New Zealand’s South Island, setting off a cascade of fault ruptures in the region. Within hours, seismic waves from the quake triggered a two-week-long slow-slip event on a section of the Hikurangi Subduction Zone between 250 and 600 kilometers north of the initial epicenter, as well as ongoing slow slip on the Hikurangi beneath New Zealand’s capital, Wellington, according to a new study in Nature Geoscience. Thanks to New Zealand’s advanced seismic and tectonic monitoring networks, the event is one of the best-documented examples of an earthquake triggering slow slip on distant faults.

21 Dec 2017

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