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!
Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg
First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy