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lucas joel

Forecasting California's earthquake hazard

In California, scientists use a model called the Uniform California Earthquake Rupture Forecast (UCERF3) to assess earthquake hazards across the state based not on the physics of the state’s faults, but on history: By considering the historic record of earthquakes, including the location and severity of past quakes, UCERF3, the third version of the model, provides a hazard measure. “But those observations are limited, because we only have a few hundred years [of written earthquake records] in California,” says Greg Beroza, a seismologist at Stanford University. “In the long term, we have a small sample of the possible behavior of the system.” This means the resulting hazard assessments, relying on the relatively short historical earthquake record, may not accurately reflect earthquake potential across the state. So, scientists have long been trying to come up with physics-based models that show how particular faults might rupture without depending on historical records — and now, they have.

04 Dec 2018

First Antarctic tetrapods

Tetrapods include all those animals with four limbs. Humans are tetrapods, as are dogs and dinosaurs and salamanders. The earliest tetrapods evolved on land from fish with bony fins during the Devonian Period between about 420 million and 359 million years ago. Until now, fossils of the earliest four-legged forms were only known from equatorial regions, but paleontologists working in South Africa now report the discovery of fossil tetrapods that lived in the Late Devonian Antarctic.

18 Oct 2018

Where will the San Andreas Fault rupture next?

In 1906, the San Andreas Fault Zone ruptured, and the shaking that followed brought the city of San Francisco to its knees. Buildings toppled and fires raged and, in the end, more than 3,000 people died as a result. Since then, Californians have often wondered aloud when and where the next “Big One” will strike. Geologists do not know the answers, but recent research has offered a new clue: Field mapping of the San Andreas’ southernmost reaches, near the Salton Sea, reveals a type of fault structure that researchers think may be just right for triggering a big earthquake.

08 Oct 2018

Earth's first footprints

As far as we know, life originated on Earth about 3.5 billion years ago, and for roughly the first 3 billion years of that history all life was microscopic. Then, during the Ediacaran Period from 635 million to 541 million years ago, the first organisms visible to the naked eye emerged. Although many members of this group, called the Ediacara biota, would have looked alien to us, some nonetheless had features we might find familiar. And according to a new study, it was Ediacaran creatures that left behind Earth’s oldest-known footprints.

05 Oct 2018

An asteroid redirected bird evolution

When an asteroid hit Earth 66 million years ago, it helped wipe out all the dinosaur lineages save one: the birds. But birds didn’t completely dodge the cataclysm the asteroid triggered. Recent research suggests that forests around the planet were devastated. With forests gone, bird species that called trees home went extinct alongside their nonavian dinosaur cousins. This means that the birds that we see living in trees today evolved from lineages that, in the aftermath of the impact, were ground-dwelling.

30 Aug 2018

Bolts of insight on earthly gamma ray showers

A handful of times between 2014 and 2016, an array of ground detectors placed in Utah’s western desert sensed something in thunderstorms that occasionally raged overhead: showers of gamma rays — the highest energy waves in the electromagnetic spectrum — occurring alongside lightning bolts.

15 Aug 2018

Seismic waves are blind to water

Geoscientists use the seismic waves produced by earthquakes to image the internal structure of the planet. Some seismic waves travel through liquids, while others do not, which is how we know, for instance, that Earth has a solid inner core and a liquid outer core.

08 Aug 2018

Mineral clue to finding perfectly preserved fossils?

The exquisitely preserved fossils found in the 500-million-year-old Burgess Shale in Canada are famous for the detailed anatomy they display. They also provide a rare and crucial record of the Cambrian Explosion, when most of the major animal groups first appeared.

17 Jul 2018

Benchmarks: June 15, 1991: Mount Pinatubo erupts

Twenty-seven years ago this month, the calm in central Luzon, the largest and most populous island in the Philippines, turned to chaos. On June 15, 1991, Mount Pinatubo disgorged 5 cubic kilometers of material over a few hours, and ash clouds soared 35 kilometers into the atmosphere. The substantial eruption — the second largest of the 20th century — burned itself into memories and history books.

15 Jun 2018

"Dam levels critical" in Cape Town

At first glance, a visitor to Cape Town might not notice the extent of the parched conditions — people still go about their business, amid the same kind of hustle and bustle you would find in other major cities. But looking closer, there are signs that something is not right. People standing in buckets to conserve water during showers is one such sign, and bottled water flying off grocery store shelves is another.

13 Jun 2018

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