It is likely that most of the large impact craters on Earth have already been discovered and that others have been erased, according to a new calculation by a pair of Purdue Univ. graduate students.
"Over the past 3.5 billion years it is thought that more than 80 asteroids similar in size to, or larger than, the one which killed the dinosaurs have struck the Earth, leaving behind craters which are over 100 kilometers across, but our model suggests only about eight of these massive craters could still exist today," says Timothy Bowling, a graduate student in Purdue’s Department of Earth, Atmospheric and Planetary Sciences. "Geologists have already found six or seven such craters, so odds are not in the favor of those hoping to find the next big crater."
Researchers from Northwestern Univ. and the Univ. of New Mexico have reported evidence for potentially oceans worth of water deep beneath the U.S. Though not in the familiar liquid form — the ingredients for water are bound up in rock deep in the Earth’s mantle — the discovery may represent the planet’s largest water reservoir.
The presence of liquid water on the surface is what makes our “blue planet” habitable, and scientists have long been trying to figure out just how much water may be cycling between Earth’s surface and interior reservoirs through plate tectonics.
Floods of molten lava may sound like the stuff of apocalyptic theorists, but history is littered with evidence of such past events where vast lava outpourings originating deep in the Earth accompany the breakup of continents.
However, new research at Michigan State Univ. shows that the source of some of these epic outpourings may not be as deep as once thought. The results, published in the journal Geology, show that some of these lavas originated near the surface rather than deep within the mantle.
Scientists have long been trying to understand how the Andes and other broad, high-elevation mountain ranges were formed. New research by Carmala Garzione, a professor of earth and environmental sciences at the Univ. of Rochester, and colleagues sheds light on the mystery.
In a paper published in the latest Earth and Planetary Science Letters, Garzione explains that the Altiplano plateau in the central Andes — and most likely the entire mountain range — was formed through a series of rapid growth spurts.
Using satellite imagery to monitor which volcanoes are deforming provides statistical evidence of their eruption potential, according to a new study led by the Univ. of Bristol published in Nature Communications.
ESA’s Sentinel satellite, launched this week, should allow scientists to test this link in greater detail and eventually develop a forecast system for all volcanoes, including those that are remote and inaccessible.
People living in the path of a deadly Washington state landslide had virtually no warning before a wall of mud, trees and other debris thundered down the mountain. Some of the homeowners didn’t even know the hillside could give way at any time.
Unlike the warning systems and elaborate maps that help residents and officials prepare for natural disasters such as floods and hurricanes, there’s no national system to monitor slide activity and no effort underway to produce detailed nationwide landslide hazard maps.
Large river networks — such as those that funnel into the Colorado and Mississippi rivers — may seem to be permanent features of a landscape. In fact, many rivers define political boundaries that have been in place for centuries.
But scientists have long suspected that river networks are not as static as they may appear, and have gathered geologic and biological evidence that suggest many rivers have been “rewired,” shifting and moving across a landscape over millions of years. Now, researchers at MIT and the Swiss Federal Institute of Technology (ETH Zurich) have developed a mapping technique that measures how much a river network is changing, and in what direction it may be moving. Their results are published in this week’s issue of Science.
Oldest Part of Crust Firms Up Idea of a Cool Early Earth
With the help of a tiny fragment of zircon extracted from a remote rock outcrop in Australia, the picture of how our planet became habitable to life about 4.4 billion years ago is coming into sharper focus.
Writing this week in the journal Nature Geoscience, an international team of researchers led by Univ. of Wisconsin-Madison geoscience Prof. John Valley reveals data that confirm the Earth’s crust first formed at least 4.4 billion years ago, just 160 million years after the formation of our solar system. The work shows, Valley says, that the time when our planet was a fiery ball covered in a magma ocean came earlier.
Scientists at the Univ. of Liverpool have shown that deep sea fault zones could transport much larger amounts of water from the Earth’s oceans to the upper mantle than previously thought.
Water is carried mantle by deep sea fault zones which penetrate the oceanic plate as it bends into the subduction zone. Subduction, where an oceanic tectonic plate is forced beneath another plate, causes large earthquakes such as the recent Tohoku earthquake, as well as many earthquakes that occur hundreds of kilometers below the Earth’s surface.
Images gathered by Univ. of Oregon scientists using seismic waves penetrating to a depth of almost 200 miles report the discovery of an anomaly that likely is the volcanic mantle plume of the Galapagos Islands. It’s not where geologists and computer modeling had assumed.
The team’s experiments put the suspected plume at a depth of 250 kilometers (155 miles), at a location about 150 kilometers (about 100 miles) southeast of Fernandina Island, the westernmost island of the chain, and where generations of geologists and computer-generated mantle convection models have placed the plume.
Seismologists say Seahawks fans shook the ground under Seattle’s CenturyLink Field during a defeat of the New Orleans Saints, causing another fan-generated earthquake.
The scientists believe the small earthquake during a Marshawn Lynch touchdown was likely greater than Lynch’s famous ”beast quake” touchdown run three years ago, which also came against New Orleans during a playoff game.
Every Thursday, Laboratory Equipment features a Scientist of the Week, chosen from the science industry’s latest headlines. This week’s scientist is Robert Hazen from the Carnegie Institution for Science. Hazen compiled a list of every plausible mineral species on the early Earth and concluded that no more than 420 different minerals would have been present at or near Earth’s surface.
A volcanic eruption has raised an island in the seas to the far south of Tokyo, the Japanese coast guard and earthquake experts say.
Advisories from the coast guard and the Japan Meteorological Agency say the islet is about 200 meters (660 feet) in diameter. It is just off the coast of Nishinoshima, a small, uninhabited island in the Ogasawara chain, which is also known as the Bonin Islands.
Find Challenges Assumptions about Makeup of Earth’s Mantle
A new discovery by researchers from the Univ. of Notre Dame’s Department of Civil and Environmental Engineering and Earth Sciences could change prevailing assumptions about the chemical makeup of the Earth’s mantle.
Antonio Simonetti, an associate professor in the department, and his doctoral student Wei Chen worked in cooperation with Vadim Kamenetsky of the Univ. of Tasmania to learn the art of conducting chemical and mineralogical analyses of melt inclusions within crystals of the mineral magnetite (Fe3O4).
Lightning strikes causing rocks to explode have, for the first time, been shown to play a huge role in shaping mountain landscapes in southern Africa, debunking previous assumptions that angular rock formations were caused by cold temperatures, and proving that mountains are a lot less stable than we think.
In a world where mountains are crucial to food security and water supply, this has vast implications, especially in the context of climate change.