The special issue will feature seismological research on all aspects of rotational ground motions (including theory, instrumentation, observation, and interpretation) and on rotations in structural response.
Rotational seismology is of interest to a wide range of disciplines, including various branches of seismology, earthquake engineering, and geodesy, as well as to physicists using Earth-based observatories for detecting gravitational waves generated by astronomical sources as predicted by Einstein in 1916.
Seismology and earthquake engineering have been based on the observation and modeling of translational ground and structural motions. Although rotational effects from earthquakes have been observed for centuries, rotational ground motion has been ignored due to a widespread belief that rotation is insignificant and practical difficulties in measuring it. Theoretical work in modern rotational seismology began in the 1970s, and attempts to deduce rotational motion from accelerometer arrays began in the 1980s. However, modern direct measurements of rotational ground motions began only about a decade ago when affordable angular sensors became sensitive enough (capable of measuring an angle of less than ten thousandth of a degree) to detect rotations from small earthquakes, while large ring laser gyros (intended for studying the Earth's rotation) became capable of detecting even smaller rotations from distant earthquakes.
Ring laser observations at Wettzell, Germany and at Piñon Flat, California demonstrated consistent measurements of rotational ground motions in the far field. The high cost of present high-precision ring laser gyros (costing $1 million or more) makes widespread deployment unlikely. Less expensive and/or less sensitive alternatives are now being pursued by five academic groups. At present, only Taiwan has a modest program to monitor both translational and rotational ground motions from regional earthquakes at several free-field sites, as well as two arrays equipped with both accelerometers and rotational seismometers in a building and a nearby site.
Based on the developments described in the BSSA special issue, observation, analysis, and interpretations of both rotational and translational ground motions will soon play a significant role in seismology and earthquake engineering.
The lead guest editor William H. K. Lee is Scientist Emeritus at the U.S. Geological Survey in Menlo Park, California. He can be reached at email@example.com.
Multi-year submarine-canyon study challenges textbook theories about turbidity currents
12.12.2017 | Monterey Bay Aquarium Research Institute
How do megacities impact coastal seas? Searching for evidence in Chinese marginal seas
11.12.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
12.12.2017 | Physics and Astronomy
12.12.2017 | Earth Sciences
12.12.2017 | Power and Electrical Engineering