Geophysics

geophysics

Small-scale factors influence mantle flow under the seafloor

In December 2011, scientists and technicians aboard the research vessel Marcus G. Langseth dropped several ocean-bottom seismometers into the deep Pacific more than 1,900 kilometers southeast of Hawaii to measure seismic activity and electrical conductivity to a depth of about 300 kilometers below the seafloor. Now, these measurements are providing new insights into how the mantle flows and deforms below the rigid tectonic plates that make up Earth’s surface.

22 Nov 2016

Mauna Loa's mysterious Ninole Hills were once a rift

Hawaii’s Nīnole Hills, jutting out from Mauna Loa’s southeast flank, are one of the most striking features on the Big Island, though their geologic origins have long been a mystery. A new study looking at gravity anomalies under the hills is revealing that the hills are part of an older rift system that predates the currently active Southwest Rift Zone. The seemingly sudden switch from one rift system to another may provide some clues as to how Mauna Loa grew to be the largest volcano on Earth. “A lot of different ideas have been proposed to explain how the Nīnole Hills were created,” says Jeff Zurek, a geophysicist at Simon Fraser University in Burnaby, British Columbia, and lead author of the new study published in Geophysical Research Letters. It’s been suggested that the hills could be the remnants of an older summit of Mauna Loa, or its predecessor, Mohokea, or that faulting and landslides could have created the unusual topography of the hills, or that they could be from an older, inactive rift system.

11 Aug 2016

Radar reveals unmarked graves

The occasional excursion to Death Valley or mineralogical study of bloodstone notwithstanding, geoscientists don’t often delve into the macabre in the course of their work. But when the administrators of two cemeteries in western New York came calling in 2014, researchers from Buffalo State College ended up using their geophysical field skills to hunt for centuries-old graves.

23 May 2016

Subducting seamounts blocked a big quake in Chile

Chile, which lies above a massive subduction zone fault, is one of the world’s most earthquake-prone countries, experiencing nine temblors of magnitude 7 or greater since 2010. In April 2014, a magnitude-8.1 earthquake struck 95 kilometers northwest of the city of Iquique, but despite its large size, the event failed to release all the stress thought to have built up along that portion of the fault. A new study reveals that a ridge of ancient underwater volcanoes may have blocked the 2014 earthquake rupture from propagating farther, thus limiting the size of the quake.
 

 

20 Jan 2016

Down to Earth With: Marine Geophysicist Maya Tolstoy

Growing up in Scotland, Maya Tolstoy was drawn to the theater, and even briefly considered majoring in the subject in college. Instead, she chose to follow another lifelong passion and became a marine geophysicist.

21 May 2015

Down to Earth With: Brian Tucker

Some of the world’s most densely populated cities are at highest risk for earthquake-related disasters. Geophysicist Brian Tucker has spent the last two-plus decades trying to help the developing world avoid such disasters, and in 1991, he founded the nonprofit GeoHazards International (GHI) to bring the developed world’s risk-mitigation techniques to high-risk communities in the developing world.

27 Apr 2015

Are slow-slip earthquakes under Tokyo stressing faults?

More than 13 million people live in Tokyo, a city that has been devastated by earthquakes in the past and is likely to be rocked again. Since the massive magnitude-9 Tohoku earthquake and tsunami in March 2011, recurrence intervals for nondamaging slow-slip quakes beneath Japan's capital have shortened. And that has left seismologists to wonder if this aseismic creep could be signaling a countdown to Tokyo's next "big one."

07 Aug 2014

Humans causing California's mountains to grow

Humankind has proven time and again that it can reshape mountains, or even tear them down. Now, it appears, we can make them rise as well. Geologists studying growth rates of the Sierra Nevada and of central California’s Coast Ranges have identified an anthropogenic contribution to the mountains’ uplift that they suggest is tied to the decades-long depletion of groundwater in the state’s Central Valley. What’s more, the researchers report in a new study published in Nature, the long-term water loss may be affecting how stress builds up on faults like the San Andreas.

14 May 2014

Precise to a fault: How GPS revolutionized seismic research

Conceived in the 1960s to provide precise time and position for the U.S. military, GPS was soon embraced by geodesists and earth scientists. Today, it is an essential tool for geoscience research that extends far below — and above — Earth's surface.

30 Apr 2014

A new tool for atmospheric studies

Scientists are putting GPS to work in some unexpected new ways, including in atmospheric research.

30 Apr 2014

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