select some parameters from those simulations based on empirical analysis and surmise how various buildings may be affected. “It is no surprise that there are certain instances where this method doesn’t work so well,” McCallen said. “Every single site is different — the geologic makeup may vary, faults may be oriented differently, and so on. So our approach is to apply geophysical research to super- computer simulations and accurately model the underlying physics of these processes.” To achieve this, the tool under development by the project team em- ploys a discretization technique that divides the Earth into billions of zones. Each zone is characterized with a set of geologic properties. Then, simulations calculate the surface motion for each zone. With an accurate understanding of surface motion in a given zone, researchers also get more precise estimates for how a building will be affected by shaking. The team’s most recent simulations at NERSC divided a 100-kilome- ter by 100-kilometer by 30-kilometer region into 60 billion zones. By simulating 30 kilometers beneath the rupture site, the team can capture how surface-layer geology affects ground movements and buildings. Eventually, the researchers would like to get their models tuned up to do hazard assessments. As Pacific Gas & Electric begins to implement a very dense array of accelerometers into its SmartMeters — a system of sensors that collects electric and natural gas use data from homes and businesses to help customers understand and reduce their energy use —McCallen is working with the utility company about potentially using that data to get a more accurate understanding of how the ground is actually moving in different geologic regions.
“The San Francisco Bay is an extremely hazardous area from a seismic standpoint and the Hayward Fault is probably one of the most poten- tially risky faults in the country,” McCallen said. “We chose to model this area because there is a lot of information about the geology here, so our models are reasonably well constrained by real data. And, if we can accurately measure the risk and hazards in the Bay Area, it’ll have a big impact.” He noted that the current seismic hazard assessment for Northern Cali- fornia identifies the Hayward Fault as the most likely to rupture with a magnitude 6.7 or greater event before 2044. Simulations of ground mo- tions from large —magnitude 7.0 or greater — earthquakes require do- mains on the order of 100 to 500 kilometers and resolution on the order of about one to five meters, which translates into hundreds of billions of grid points. As the researchers aim to model even higher-frequency motions between 5-10 hertz, they will need denser computational grids and finer time-steps, which will drive up computational demands. The only way to ultimately achieve these simulations is to exploit exascale computing, McCallen said. In addition to leading an ECP project, McCallen is also a Berkeley lab research affiliate and associate vice president at the University of California Office of the President. This work was done with support from Exascale Computing Project, a collaborative effort between the DOE’s Office of Science and National Nuclear Security Agency. NERSC is a DOE Office of Science User Facility.
Information provided by Lawrence Berkeley National Laboratory (www.lbl.gov).
VIA 57 West in New York City wins 2016 best new skyscraper. Skyscraper Top 10
The winner of the annual Emporis Skyscraper Award for the best new skyscraper of the year is a 34-story residential building, VIA 57 West in New York City. The winner was picked by an international panel of experts from a worldwide pool of more than 700 eligible skyscrap- ers that were completed in 2016 and are at least 100 meters tall. The award, given by Emporis, an international provider of building data, is being presented for the 17th time this year. The pyramid-shaped winner, designed by Danish architects BIG-Bjarke Ingels Group, was recognized by the award jury for its fascinating and extraordinary shape, which breaks new ground in design. VIA 57 West is a hybrid between a European perimeter block and a classic American skyscraper.
VIA 57West is a hybrid between a European perimeter block and a classic American skyscraper. Photo: ©Royce Douglas
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