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Tech-Op-ed June, 2020 SOUNDING OFF


By Michael Skinner Editor


Listen Carefully, You Can Hear the Earth


W


hile most of the impacts of coronavirus have been discussed in terms of human life and economic damage — and rightly so — another side effect has been discovered: the Earth is quieter.


Seismic noise is a persistent vibration of the Earth’s surface, with low-


frequency waves below 1 hertz mainly due to ocean waves. Around 1 hertz, rivers, wind and other atmospheric phenomena generate ground vibrations. Above 1 hertz, seismic noise is often caused by human activities, such as large-scale industrial machinery. A significant drop in this seismic background noise was recently report-


ed from the Royal Observatory of Belgium, located in Brussels. Seismologist Thomas Lecocq was the first to identify the decrease, which began in mid- March. This was around the time that the country closed businesses and schools and implemented social distancing. Lecocq says that this reduction is similar to what seismologists see once a year on Christmas Day. This reduction in seismic noise has been significant enough that the ob-


servatory’s surface instruments are able to detect small earthquakes as accu- rately as a detector buried nearly 330 feet underground. Belgium is not the only country to detect a drop in seismic noise. Re-


searchers around the world, including in the United States, England, Scot- land, France, and New Zealand, have all reported similar results since isola- tion began. According to Lecocq, this phenomenon is proof that people are following


the guidelines set in place to limit the spread of the virus. “From the seismo- logical point of view, we can motivate people to say ‘OK look, people. You feel like you’re alone at home, but we can tell you that everyone is home. Every- one is doing the same. Everyone is respecting the rules,” he says. Seismic noise was first recorded toward the end of the 19th century. Over


the last 100 years, scientists have been careful to separate “seismic hums” from some strange and persistent low-frequency acoustic “hums,” such as the Taos Hum in New Mexico and the Auckland Hum in New Zealand. The origins of these mysterious, and sometimes audible, sounds are still


unknown. However, the fact that they can be heard at all suggests that they generate some frequencies above 20 hertz, which is around the lowest fre- quency that the human ear can detect. Seismic hum and microseisms are far beyond the range of human hearing. In the U.S., a research team at Stanford University is taking advantage


of the recent stillness to track seismic noise using a fiber optic network under Palo Alto. The team found that their fiber optic network data is so accurate that it can spot individual cars passing by on the surface. Nate Lindsey, who is leading the study, has been focusing on fiber optic


DAS (distributed acoustic sensing). In essence — sound from light. His re- search has been to further develop this emerging photonic tool, which trans- forms telecommunications fiber optics into a dense ground motion array. To- day’s commercialized systems typically use coherent optical time domain re- flectometry (COTDR) to measure Rayleigh backscattering. A laser pulse is sent down the fiber and is scattered at various points, acting as a distributed interferometer. The laser’s reflected intensity is then measured as a function of time after transmission. This type of process has high enough resolution that it can detect ground traffic and gas pipe leaks to within feet of the source. Back in Belgium, Lecocq says that vibrations attributed to human activ-


ity have dropped by nearly a third, since the beginning of coronavirus contain- ment. We should be encouraged by the fact that our virus control methods are working, as much of the world begins to see a decrease in new infections, and more importantly, lives lost. In the meantime, let’s join the Earth in a moment of silence. r


PUBLISHER’S NOTE


By Jacob Fattal Publisher


Trade Shows Go Virtual D


espite the difficulty of the past few months, the rest of 2020 has much to look forward to. I am encouraged by the response of the electronics industry in this time of crisis. U.S. Tech has witnessed and reported on


story after story of manufacturers jumping into the trenches with their local communities to build ventilators, prop up fragmented supply chains and reor- ganize resources and equipment to support critical medical devices —all while protecting their employees with the necessary gear and strict social distanc- ing measures. A large part of our industry, though, is grappling with this new reality.


Many trade shows have been postponed or canceled, due to the simple difficul- ty of travel and putting people in close proximity to others. However, a new style of trade show and exhibition may take off as a result. SEMICON West, now in its 50th year, will be held virtually this July.


Exhibitors will be given virtual booth space in which they can promote their products and services, as well as upload multimedia content and links to the web. Also, live chat channels are expected to be available for participants to interact directly with company representatives, as well as group meetings, technical sessions, and networking events. This year’s show promises to pro- vide ready access to post-show analytics for exhibitors. There are a number of potential benefits to holding a virtual trade show.


First, the expense and time of travel is completely eliminated. Also, product demonstrations and technical materials can be easily accessed at any time, downloaded and repeated at will. Keynotes, technical sessions and panel dis- cussions can be recorded and viewed whenever it is convenient, as well as re- watched later on. With the emphasis over the past few years on networking and interlink-


ing production systems, there are many opportunities to leverage this connec- tivity in a virtual environment. Nearly every major show over the last two years has been demonstrating some sort of live “smart” production line. It would be interesting to see how companies use this software and connectivity to demo their equipment virtually. In the future, it would be useful to take some of these components and


complement traditional trade shows. While there is no replacement for the face-to-face interaction with friends and colleagues and the hands-on experi- ence with technology that these exhibitions offer, a broader web-based envi- ronment, on top of a physical exhibition, may begin to separate the best shows from the rest of the pack. r


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