Research attempts to better understand deadly pyroclastic flows
An empty boiler house and 1.5 tons of thick volcanic ash have given researchers at New Zealand's Massey University and Georgia Tech a look into the inner workings of pyroclastic flows in the largest-scale experiments of volcanic flows that have been conducted. They saw something they didn't expect.
Researchers created their own flows with 3,500 pounds of volcanic ash
Credit: Massey University
In a paper published last week by Nature Geoscience, the team describes two separate transport areas that have been well-studied: a non-turbulent underflow and a fully turbulent, ash cloud region at the top of the flow. But volcanic flows apparently have a previously unrecognized third zone where the currents meet.
"Inside this middle zone, the gas-particle mixture behaved fundamentally differently from the turbulent suspension cloud above and the particle-rich avalanche of pumice below," said Massey's Gert Lube. "These mesoscale turbulence clusters control how the internal structure and the damage potential of pyroclastic flows evolves during volcanic events."
Pyroclastic flows, like the ones that covered Pompeii, are avalanches of fast-moving clouds of hot ash, rock and gas that are emitted during eruptions. They are responsible for 50 percent of volcanic fatalities every year.
"Our experiments allow us to better understand the physics of something we'll never see: the inside of an actual volcanic flow," said Massey's Eric Breard, the lead author who will begin a postdoctoral fellowship at Georgia Tech in January. "By studying how quickly this mesoscale region grows, and how its dynamics change, it ultimately can tell us how dangerous the flows can be."
To create and measure the flows, the team used Massey's one-of-a-kind eruption simulator. The team climbed a 12-meter tower in a repurposed boiler house and poured more than 3,500 pounds of pumice and ash down a 12-meter narrow chute. High-speed cameras recorded the flow while sensors captured the data.
"These experiments demonstrated that in the intermediate transition zone between the fully turbulent upper part of the flow and the underlying concentrated underflow, the energy from the largest scales of fluid motion is extracted by particles that almost exactly follow the fluid motion," said co-author Josef Dufek, an associate professor at Georgia Tech. "This creates dendritic structures, or waves of particles, that slow the flow down, and provide the rate-limiting step for particles entering the underflow where they can cause the most damage."
"This opens a new path toward reliable predictions of their motion, and will be particularly topical for hazard scientists and decision makers, because they will lead to major revisions of volcanic hazard forecasts and ultimately more effective measures for keeping people safe," said Lube.
Massey and Georgia Tech also received support from scientists at the University of Auckland and State University of New York.
Jason Maderer | EurekAlert!
NASA sees quick development of Hurricane Dora
27.06.2017 | NASA/Goddard Space Flight Center
Collapse of the European ice sheet caused chaos
27.06.2017 | CAGE - Center for Arctic Gas Hydrate, Climate and Environment
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Earth Sciences
27.06.2017 | Earth Sciences
27.06.2017 | Life Sciences