{"199531":{"#nid":"199531","#data":{"type":"news","title":"Hearing the Russian Meteor, in America","body":[{"value":"\u003Cp\u003EHow powerful was February\u2019s meteor that crashed into Russia? Strong enough that its explosive entry into our atmosphere was detected almost 6,000 miles away in Lilburn, Ga., by infrasound sensors \u2013 a full 10 hours after the meteor\u2019s explosion. A Georgia Tech researcher has modified the signals and made them audible, allowing audiences to \u201c\u003Ca href=\u0022https:\/\/www.youtube.com\/watch?v=i1ey5zc6TOo\u0022\u003Ehear\u201d what the meteor\u2019s waves sounded like\u003C\/a\u003E as they moved around the globe on February 15.\u0026nbsp; \u003C\/p\u003E\u003Cp\u003ELilburn is home to one of nearly 400 \u003Ca href=\u0022http:\/\/www.usarray.org\/\u0022\u003EUSArray\u003C\/a\u003E seismic\/infrasound stations in use in the eastern United States. They are part of a large-scale project named \u201cEarthscope,\u201d an initiative funded by the National Science Foundation that studies the Earth\u2019s interior beneath North America. The stations are mainly deployed to record seismic waves generated from earthquakes, but their sound sensors can record ultra long-period sound waves, also known as infrasound waves. \u003C\/p\u003E\u003Cp\u003EThe human ear cannot hear these infrasound signals. However, by playing the data faster than true speed, Georgia Tech faculty member Zhigang Peng increased the sound waves\u2019 frequency to audible levels. The \u003Ca href=\u0022http:\/\/www.iris.edu\u0022\u003EIncorporated Research Institutions for Seismology\u0027s Data Managment Center\u003C\/a\u003E provided the data. \u003C\/p\u003E\u003Cp\u003E\u201cThe sound started at about 10 hours after the explosion and lasted for another 10 hours in Georgia,\u201d said Peng, an associate professor in the School of Earth and Atmospheric Sciences. He\u2019s confident that the sound is associated with the meteor impact because a slow propagation of the sound waves can be seen across the entire collection of USArray stations, as well as other stations in Alaska and polar regions. \u003C\/p\u003E\u003Cp\u003E\u201cThey are like tsunami waves induced by large earthquakes,\u201d Peng added. \u201cTheir traveling speeds are similar, but the infrasound propagates in the atmosphere rather than in deep oceans.\u201d\u003C\/p\u003E\u003Cp\u003EScientists believe the meteor was about 55 feet in diameter, weighed more than 7,000 tons and raced through the sky at 40,000 miles an hour. Its energy was estimated at 30 nuclear bombs. More than 1,500 people were hurt. \u003C\/p\u003E\u003Cp\u003EUsing the same sonification process, Peng also converted seismic waves from North Korea\u2019s nuclear test on February 12 and an earthquake in Nevada the next day. Each registered as a 5.1 magnitude event but created \u003Ca href=\u0022https:\/\/www.youtube.com\/watch?v=mRi2elVdp-o\u0022\u003Edifferent sounds\u003C\/a\u003E. The measurements were collected by seismic instruments located about 100 to 200 miles from each event. For further comparison, Peng has also created a \u003Ca href=\u0022https:\/\/www.youtube.com\/watch?v=ULlduyvqT4c\u0022\u003Eseismic recording of the meteor impact\u003C\/a\u003E at a similar distance. \u003C\/p\u003E\u003Cp\u003E\u201cThe initial sound of the nuclear explosion is much stronger, likely due to the efficient generation of compressional wave (P wave) for an explosive source,\u201d said Peng. \u201cIn comparison, the earthquake generated stronger shear waves that arrived later than its P wave.\u201d\u003C\/p\u003E\u003Cp\u003EPeng says the seismic signal from the meteor is relatively small, even after being amplified by 10 times. According to Peng, this is mainly because most of the energy from the meteor explosion propagated as the infrasound displayed in the initial sound clip. Only a very small portion was turned into seimsic waves propagating inside the Earth. \u003C\/p\u003E\u003Cp\u003EThis isn\u2019t the first time Peng has converted seismic data into audible files. \u003Ca href=\u0022http:\/\/www.gatech.edu\/newsroom\/release.html?nid=111701\u0022\u003EHe also sonified\u003C\/a\u003E 2011\u0027s historic Tohoku-Oki, Japan, earthquake as it moved through the Earth and around the globe.\u003C\/p\u003E\u003Cp\u003EThe seismic and sound data generated by the meteor impact and other sources can be used to demonstrate their global impact. Scientists are also using them to better understand their source characterizations and how they propagate above and inside the earth.\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Sound Arrived in 10 Hours, Lasted 10 More"}],"field_summary":[{"value":"\u003Cp\u003EHow powerful was February\u2019s meteor that crashed into Russia? Strong enough that its explosive entry into our atmosphere was detected almost 6,000 miles away in Lilburn, Ga., by infrasound sensors \u2013 a full 10 hours after the meteor\u2019s explosion.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"How powerful was February\u2019s meteor that crashed into Russia? Strong enough that its explosive entry into our atmosphere was detected almost 6,000 miles away in Lilburn, Ga."}],"uid":"27560","created_gmt":"2013-03-14 15:10:35","changed_gmt":"2016-10-08 03:13:51","author":"Jason Maderer","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2013-05-03T00:00:00-04:00","iso_date":"2013-05-03T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"66060":{"id":"66060","type":"image","title":"Zhigang Peng, USGS Study","body":null,"created":"1449176916","gmt_created":"2015-12-03 21:08:36","changed":"1475894587","gmt_changed":"2016-10-08 02:43:07","alt":"Zhigang Peng, USGS Study","file":{"fid":"193278","name":"zhigang_peng.usgs_.jpg","image_path":"\/sites\/default\/files\/images\/zhigang_peng.usgs_.jpg","image_full_path":"http:\/\/tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/zhigang_peng.usgs_.jpg","mime":"image\/jpeg","size":1846248,"path_740":"http:\/\/tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/zhigang_peng.usgs_.jpg?itok=TVxxegrX"}}},"media_ids":["66060"],"groups":[{"id":"1183","name":"Home"}],"categories":[{"id":"135","name":"Research"}],"keywords":[{"id":"61541","name":"Earth and Atmospheric Sciences"},{"id":"5770","name":"Earthquake"},{"id":"61531","name":"Meteor"}],"core_research_areas":[{"id":"39501","name":"People and Technology"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJason Maderer\u003Cbr \/\u003EMedia Relations\u003Cbr \/\u003E\u003Ca href=\u0022mailto:maderer@gatech.edu\u0022\u003Emaderer@gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-385-2966\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","format":"limited_html"}],"email":["maderer@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}