Chelyabinsk sky rendering is a reconstruction of the asteroid that exploded over Chelyabinsk, Russia on Feb. 15, 2013. 
Credit: Sandia National Laboratories.

The consequences of incoming space objects plowing into Earth’s atmosphere and resulting human injuries are being spotlighted during the upcoming 81st Annual Meeting of The Meteoritical Society, being held July 22-27 in Moscow, Russia.

The entry of the roughly 65-foot (20-meter) sized meteoroid at Chelyabinsk on February 15, 2013, stands out from other fireballs for its magnitude and the large zone of destruction on the ground caused by its airburst.

That’s the word from researcher Anna P. Kartashova of the Institute of Astronomy within the Russian Academy of Sciences. In a paper by Kartashova and colleagues to be presented at the scientific gathering, the Chelyabinsk event was extremely well documented. The observational database includes photos, video, infrasound, seismic data and more – including eyewitness accounts of the airburst that provide information not recorded by instrumental devices.

Type of injuries

“According to the interviews conducted via the internet, respondents had cuts or bruises, reported sunburn, hurt their eyes, mentioned retina burns (no official verification), were briefly stunned by the shockwave, or reported a brain injury in the form of a concussion or headache,” Kartashova and colleagues report.

In-person and phone interviews, along with internet surveys add up to about 3,000 accounts being collected. “They provide information about sensations of heat, smells, sounds, the occurrence of sunburn, and the type of injuries sustained,” Kartashova and collaborators explain.

The Chelyabinsk event proved that the meteoroid, previously not classified as hazardous under Asteroid/Comet Hazardous classification, “can cause significant damage” and a “significant number of injuries” if the impact occurs near a populated area, the research team concludes.

Earth has been on the receiving end of several incoming objects resulting in human injury.
Credit: NASA

Tunguska impact

Peter Jenniskens of the SETI Institute in Mountain View, California has led a look back in time, documenting the Tunguska event in Siberia on June 30, 1908.

“The eye witness accounts of the Tunguska event at various distances from the epicenter confirm a more significant impact than the recent Chelyabinsk airburst event, with more dramatic consequences,” Jenniskens and his fellow researchers report.

Credit: NASA/JPL

 

Even though Tunguska impact was in a sparsely populated region, Jenniskens and colleagues say there is strong evidence in the written record of at least three casualties from this event.

Epicenter effects

Recorded eye witness reports were mostly collected long after the event in 1921-1930, 1938, 1959-1969 and many accounts retell the stories of other people.

Scattered in the region were local reindeer nomads, Evenks – the most numerous and widely strewn of the many small ethnic groups of northern Siberia.

Credit: Leonid Kulik Expedition, Wikipedia

The trading post Vanavara was located at about 40 miles (65 kilometers) from the epicenter of the event.

Eyewitness reports that contained information on injuries were extracted from a catalogue of eyewitness accounts. The locations of reported injuries are only approximately known, mainly in the region up to 186–310 miles (300-500 kilometers from the epicenter.

Stress and panic

Furthest from the event, injuries were mainly in the form of signs of stress and panic, sometimes accompanied by reports of objects falling from high places (bench, roof, Russian stove).

About 50 eyewitness reports describe events in locations closer than 80 miles (130 kilometers) from the blast.

“More serious injuries occurred there,” the Jenniskens-led paper notes. “The injuries mentioned include concussions, being stunned or fainting, a broken arm, burns, aphasia and blindness. Concussion and fainting were the most often mentioned. Fainting could be long lasting, up to two days,” Jenniskens and colleagues say.

Rare opportunities

The effect of thermal radiation from nuclear explosions is often used in radiation hazard assessments. However, the Jenniskens-led paper adds that the spectral dependence of radiation emitted during an asteroid impact can be different from the spectral radiation emitted by a nuclear explosion.

“Therefore, all theoretical approaches to risk assessment should be verified by observations, and the Chelyabinsk and Tunguska events provide rare opportunities to do so,” Jenniskens and his fellow scientists conclude.

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