By By Nancy Houser Sep 16, 2011 in Science Strange unearthly sounds heard around Earth are perplexing scientists, especially when similar sounds are heard at the same time. The sounds are described as "running trains," while others are described as trumpets or booming sounds. All are unearthly. "What's going on is an interesting challenge, whatever it might be," said seismologist David Hill, scientist emeritus at the U.S. Geological Survey office in Menlo Park, Calif., in the article, "Mysterious 'Booming Sounds' Heard Around World Perplex Scientists." "It seems there is quite a range of processes in nature that might be responsible." Some of the enigmas he was referring to were rock bursts, earthquakes, tsunamis, meteors, mud volcanoes, explosive venting of gases, distant thunder and booming sands. Another natural suggestion were meteor shower sounds captured in space. One such example is the According to Hill, the Additionally, a flexible component array is available for deployment where a denser network of seismometers is required. Another array of USGS seismometers is also available. USArray is charged with the real time seismic data that is collected, transmitted, checked for quality, archived and is accessible online for the general public and researchers. This research by Hill will be detailed in the September-October journal of Seismological Research Letters. YouTube.com is full of videos displaying strange sounds from all over the world, with viewers asking for explanations. They vary in countries and states---with many heard at the same time but in different locations of Earth, such as the sounds in southern Sweden Some of the enigmas he was referring to were rock bursts, earthquakes, tsunamis, meteors, mud volcanoes, explosive venting of gases, distant thunder and booming sands. Another natural suggestion were meteor shower sounds captured in space.One such example is the Perseid meteor shower , which sound exactly like some of the sound heard in the videos. In Life's Little Mysteries, this clip was captured by the U.S. Air Force Space Surveillance Radar in Texas as it echoed the Perseid showers, a 2,000 year-old event.According to Hill, the USArray is moving across the eastern part of the United States, and "it might help resolve the issue of what the sounds on the North Carolina coast are." USArray is one of three components of the Earthscope project , a portable array of 400 seismometers deployed across the United States over a ten-year period.Additionally, a flexible component array is available for deployment where a denser network of seismometers is required. Another array of USGS seismometers is also available. USArray is charged with the real time seismic data that is collected, transmitted, checked for quality, archived and is accessible online for the general public and researchers.This research by Hill will be detailed in the September-October journal of Seismological Research Letters. More about unearthly, Sounds, Earth, perplex, Scientists unearthly Sounds Earth perplex Scientists