Tag archives: geophysics
By Tushna Commissariat
Plumbing problems do not get any bigger and more complicated than a backed-up volcano. But geophysicists looking at the responses of ground waves below Japanese volcanoes have now come up with a technique for identifying where pressurized volcanic fluids build up, allowing them to better anticipate when a volcano may erupt. Scientists already knew that seismic waves from large earthquakes agitate volcanic systems and that large eruptions generally follow a build-up of pressurized fluids at some depth. But they had been unable to pin down the specific physical changes that seismic waves cause. Now though, Florent Brenguier of the Institut des Sciences de la Terre in Grenoble, France, and colleagues at the University of Tokyo have used recordings of seismic-wave velocity from the devastating 2011 Tōhoku earthquake to create a map of seismic-velocity changes in its aftermath. Surprisingly, the largest changes were not observed in the area closest to the earthquake epicentre near the Pacific coast but farther inland, immediately below volcanic regions. The image above highlights an anomalously low seismic velocity below the Mount Fuji volcano after the earthquake, despite it being some 500 km from the epicentre. The drop in velocity is because the regions are susceptible to earthquake shaking – cracks in the crust open so that fluids at high pressures can escape, and could be seen as proxies for the high-pressure fluid build-up (Science 345 80).
By Matin Durrani
We’re not the kind of people here at Physics World who resort to national stereotypes – if anything, physicists are pretty much the same the world over no matter where they’re from.
But in the case of Spain, there is a widely held (and probably unfair) view that the Spanish are a bit on the lazy side, saddled with a reputation for long lunches, snoozy siestas and late nights out.
In fact, the Spanish are aware of the problem and there has been much debate in the Spanish media over what can be done to improve productivity and working lives. A Spanish parliamentary commission last year even proposed that the country should turn its clocks back by an hour from Central European Time (CET) to Greenwich Mean Time (GMT). Doing so, the commision said, would improve “productivity, absenteeism, stress, accidents and school drop-out rates”.
By Tushna Commissariat
In case you missed it, I was at the APS March meeting in Denver, Colorado last week and I was blogging about a whole host of interesting talks and sessions that I attended. Although I am back in Bristol now, there were one or two other talks that I thought covered some very interesting physics, so here’s a catch-up.
Slip slidin’ away
Seasoned physicsworld.com readers will remember that earlier this year, we featured a rather intriguing story on the phenomenon of earthquake lights – the mysterious and unpredictable glowing lights that seem to appear before some earthquakes. First documented in the 1600s and seen as recently as the Fukushima earthquake of 2011, the “unidentified glowing objects” add to the long list of possible earthquake precursors, and so are of interest. The study that we wrote about in January looked at 65 well-documented events of such lights and concluded that they may occur thanks to a particular type of geological fault – a subvertical fault – causing the earthquake.
By Matin Durrani in Rio de Janeiro
I don’t think I’ve ever talked to the head of a physics lab with a parrot screeching outside the window. But that was the case today when I visited the Brazil’s National Observatory – the country’s oldest scientific institution, founded in 1827 by Emperor Dom Pedro I just five years after the country won independence from Portugal.
The parrot was somewhere in the lush green trees directly outside the open windows of the director’s elegant first-floor office, which is currently occupied by the physicist Joao dos Anjos, who took over as head of the observatory earlier this year. (He also claimed his secretary had seen a ghost in the office recently, but that’s another story.)
After closing the windows’ shutters and switching on the air-conditioning, Dos Anjos explained how the observatory is now focused on three main activities – astronomy, geophysics and metrology. In fact, the observatory is still the official body in Brazil for setting time, which was one of its original missions, along with determining geographical locations and studying the country’s climate.