Meteor’s infrasound shockwave, “Property ruined and spared”


According to a New York Times report, the meteor that struck in Russia on 15th of February shattered glass and ruined property in random fashion.   This was the largest reported meteor to enter earth’s atmosphere since 1908.  This article, written by Andrew D Kramer begins by describing a roof that was “sheared” off of a “brick and steel factory building”,while a nearby “glass facade” was left intact.

Kramer writes about the meteor strike that shook Siberia:

In some high-rises in this city, the first modern urban community to have felt the breath of a cosmic close encounter, every window blew out on the top floor; elsewhere, the ground floors suffered.

More ominously, reports came in to local news media over the weekend of stranger phenomena: behind unshattered apartment windows, glass jugs were said to explode into shards, dishes to crack, electronics to die. Balconies rattled. One man said a bottle broke right in his hand.

So, what would cause the seeming random damage reported by the city of Chelyabinsk?  This is where the infrasound shock waves come into the equation, according to the article:

What shattered the glass, scientists say, was both the explosion as the meteor fragmented and the waves of pressure created as it decelerated. Such low-frequency waves — called infrasound — are sometimes detected by cold-war era nuclear blast sensors in remote parts of the Pacific Ocean or Alaska, according to meteor experts.

The waves can bounce off buildings and be stronger in some places than others; they can also resonate with glass, explaining why bottles and dishes might have shattered inside undamaged kitchens, as if crushed by the airy hand of the meteor itself.

“A shock wave is like a ball,” Aleksandr Y. Dudorov, director of the theoretical physics department at Chelyabinsk State University, said in an interview. “Throw a ball into a room and it will bounce from one wall to another.”

Richard P. Binzel from MIT is also consulted about the dynamics of the infrasound meteor waves.  Kramer writes:

Infrasound waves have not previously been studied in a cityscape, Richard P. Binzel, a professor of planetary science at the Massachusetts Institute of Technology and an author of a textbook on asteroids and meteorites, said in a telephone interview. But he noted that the apparent randomness of the damage was consistent with the way such waves function.

“A shock wave can be coming from a particular direction, and if you face that direction you are more susceptible,” Dr. Binzel said.

“One building might shadow another, or you may have a street that is optimally aligned to channel the wave, either in a fortunate or unfortunate way.”

Read the full article here.


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