Geology

A new discovery in the study of how lava dome volcanoes erupt may help predict how a volcanic eruption will behave.

Volcanologists say a process called frictional melting plays a role in determining how a volcano will erupt, by dictating how fast magma can ascend to the surface, and how much resistance it faces en-route.

The process occurs in lava dome volcanoes when magma and rocks melt as they rub against each other due to intense heat. This creates a stop start movement in the magma as it makes its way towards the earth's surface. The magma sticks to the rock and stops moving until enough pressure builds up, prompting it to shift forward again, a process called stick-slip. 


University of California, Berkeley, geologist William Dietrich pioneered the application of airborne LIDAR, light detection and ranging, to map mountainous terrain, stripping away the vegetation to see the underlying ground surface - but he still couldn't see what was under the surface: the depth of the soil, the underlying weathered rock and the deep bedrock.

He and geology graduate student Daniella Rempe have now proposed a method to determine these underground details without drilling, potentially providing a more precise way to predict water runoff, the moisture available to plants, landslides and how these will respond to climate change.


The oldest sections of transform faults, such as the North Anatolian Fault Zone and the San Andreas Fault, produce the largest earthquakes, putting important limits on the potential seismic hazard for less mature parts of fault zones, according to a new presentation ("Fault-Zone Maturity Defines Maximum Earthquake Magnitude") at the Seismological Society of America 2014 Annual Meeting in Anchorage.


When and where did the ancient Iapetus Ocean suture (the most fundamental Appalachian structure) form? Is part of New England made up of ancient African-derived rocks? What is the Moretown terrane? 

Mountain-building events, called "orogenies," in the northern U.S. Appalachia record the closure of the Iapetus Ocean, an ancient precursor to the Atlantic. The Iapetus separated continental fragments of ancestral North America and Africa more than 450 million years ago.


Parts of the landscape underlying the massive Greenland ice sheet may have been undisturbed for almost 3 million years, since the island became completely ice-covered, say researchers who based their discovery on an analysis of the chemical composition of silts recovered from the bottom of an ice core more than 3,000 meters long. 

The find suggests "pre-glacial landscapes can remain preserved for long periods under continental ice sheets." 

In the time since the ice sheet formed "the soil has been preserved and only slowly eroded, implying that an ancient landscape underlies 3,000 meters of ice at Summit, Greenland," they conclude.


Geologists have analyzed 40 meteorites that fell to Earth from Mars those chemical signatures have revealed some secrets of the early Martian atmosphere.

The atmospheres of Mars and Earth diverged in important ways very early in the 4.6 billion year history of our solar system.

Of course, what everyone wants to know is if life ever existed there and how water flowed in the past. Those answers are still waiting to be found but researchers are learning where to look.


The Tibetan Plateau — the world's largest, highest, and flattest plateau — had a larger initial extent than previously documented.  

Known as the "Roof of the World," the Tibetan Plateau covers more than 970,000 square miles in Asia and India and reaches heights of over 15,000 feet. The plateau also contains a host of natural resources, including large mineral deposits and tens of thousands of glaciers, and is the headwaters of many major drainage basins.


The Moon formed nearly 100 million years after the start of the solar system, according to a paper based on measurements from the interior of the Earth combined with computer simulations of the protoplanetary disk from which the Earth and other terrestrial planets formed.

The team of researchers simulated the growth of the terrestrial planets (Mercury, Venus, Earth and Mars) from a disk of thousands of planetary building blocks orbiting the Sun.

By analyzing the growth history of the Earth-like planets from 259 simulations, the scientists discovered a relationship between the time the Earth was impacted by a Mars-sized object to create the Moon and the amount of material added to the Earth after that impact.


The repeated cycles of plate tectonics throughout history that led to collision, assembly and disruption of large supercontinents have produced modern continents that are collages of bits and pieces of each other.

Figuring out the origin and make-up of continental crust formed and modified by these tectonic events is a vital to understanding Earth's geology and is important for many applied fields, such as oil, gas, and gold exploration. In many cases, the rocks involved in these collision and pull-apart episodes are still buried deep beneath the Earth's surface, so geologists must use geophysical measurements to study these features. 


The largest earthquakes occur where oceanic plates move beneath continents. Obviously, water trapped in the boundary between both plates has a dominant influence on the earthquake rupture process.

Writing in
Nature Geoscience (28.03.2014), a group of scientists from the GFZ German Research Centre for Geosciences and from Liverpool University analyzed the Chile earthquake of February, 27th, 2010 and found that the water pressure in the pores of the rocks making up the plate boundary zone was key.