Researchers build better earthquake simulator

first_imgThe apparatus with builder Joel Young. Credit: Science DOI: 10.1126/science.1221195 More information: Rapid Acceleration Leads to Rapid Weakening in Earthquake-Like Laboratory Experiments, Science 5 October 2012: Vol. 338 no. 6103 pp. 101-105. DOI: 10.1126/science.1221195ABSTRACTAfter nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth’s crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our experiments are proxies of fault-patch behavior during earthquakes of moment magnitude (Mw) = 4 to 8. We show that seismically determined earthquake parameters (e.g., displacement, velocity, magnitude, or fracture energy) can be used to estimate the intensity of the energy release during an earthquake. Our experiments further indicate that high acceleration imposed by the earthquake’s rupture front quickens dynamic weakening by intense wear of the fault zone. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Researchers build better earthquake simulator (2012, October 5) retrieved 18 August 2019 from https://phys.org/news/2012-10-earthquake-simulator.html Real earthquakes generally occur when the pressure between geological plates pressing against one another reaches a “breaking point.” But, because each plate is interfering with the other’s movement, one invariably slides beneath the other in a slipping and catching process which results in the ground above undulating in an unpredictable fashion. Creating models with the same effects allows researchers to better understand the whole process, and allows urban planners to build better, more earthquake-proof structures. Unfortunately, most models haven’t been able to produce the huge energy release found in real earthquakes. In this new effort, the research team attempted to replicate a massive energy burst onto a sample of rock, rather than the slow crushing energy generally replicated. To make this happen, they attached a clutch to a 500-pound flywheel that, at a set point, grabbed a large piece of disk-shaped granite and pressed it against the flywheel. The pressing caused energy to be quickly transferred to the granite, making it spin. This configuration more faithfully represents the events of real earthquakes, the researchers suggest, because it allows for the sudden transfer of energy into rock that happens when the breaking point is reached. In review of their research results, the team found similarities between the characteristics of the granite disks, and rock samples taken from earthquake fault areas, thereby suggesting that their experiment closely emulated what happens to rock in earthquake zones. They also found that by varying the flywheel speed they could create earthquake simulations for various magnitudes ranging from four to eight. © 2012 Phys.orglast_img