What if the Chelyabinsk event occurred in a remote region such as Antarctic, or over some remote ocean?
Would we know the event happened, the magnitude of the event, and if so what monitoring system would pick that up?
Even with monitoring satellites, we still don’t know (publicly) about the 1979 Vela Incident, a.k.a., South Atlantic Flash.
As njtt implies, the Tunguska event provides an illustrative example, although he/she doesn’t give any direct information.
despite taking place in 1908, the Tunguska explosion was recorded by seismometers all over the world, as well as by microbarometers worldwide. It’s fair to say, though, that these events probably wouldn’t have been correlated unless someone had an inkling that it occurred. Indeed, the records sat for many years until someone, knowing of the event, decided to comb through the record looking for it.
More immediate were the noctilucent clouds just following the event. These clouds, catxching sunlight from over the horizon, lit up the European skies so brightly that you could read newspapers out of doors. The Scandinavian astronomer Torvald Kul correctly surmised that a large meteorite had fallen in Siberia, and that the dust injected into the atmosphere was responsible.
It was years, however, until word filtered out of Siberia to the “civilized” world. A report from a Siberian newspaper was reprinted onto a page of one of those tear-off-a-day calendars in Russia, where someone gave it to Leonid Alexeyeitch Kulik, who finally organized an expedition to the site in 1927. (There had been a revolution and a world war an countrywide re-organization, so don’t blame him for the long delay. They had to get a special pass from the NKVD, the pre-KGB secret police organization, just to run a train of scientists out there) After he saw it, he organized several more expeditions, even aerially mapping the “explosion” site.
GLOBAL DETECTION OF AIRBURSTS: A COMBINED SATELLITE - INFRASOUND STUDY (pdf)
with respect to ultrasound detection. The Chelyabinsk event has been pegged at 500 kT so we should be hearing a number of these, if we’re listening of course.
If we don’t know about it, why is there a Wikipedia page?
Or is the OP referring to the Chelyabinsk meteor in February this year?
Please forgive me if I was not clear enough.
Yes I was referencing the event near Chelyabinsk in Siberia of February of this year.
As I read things we know quite a bit about it as it was recorded by many dash cams in cars and near a city of some 1 million people that felt the effect of the blast.
My question is if a similar event occurred this afternoon over a remote part of the world would we all be aware of that, and if so how? Or just all blissfully unaware.
A 20kT blast would be detectable globally using the IMS Infrasound Network.
From my earlier link and this site : IMS Infrasound Network
Though I had stated earlier ultrasound the reference was to infrasound.
I know the Chelyabinsk meteor trail was photographed by a Meteosat satellite, but that seems to have been just luck as they only capture images once every 30 minutes according to that page. The USA also has the GOES geostationary satellites which cover most of the Earth’s surface but I’m not sure whether that is continuous or just a series of images at intervals…
It was quite clear to me that he was, especially as he explicitly referred to it, by name, so I was providing a link to information about a similar (though much larger) event that happened in a remote region and was not directly observed, which was what he asked about.
Of course, Tunguska, being so much larger, is atypical. I would not be surprised if there have been many Chelyabinsk sized events in modern times that occurred over the oceans or unpopulated land that no-one ever knew anything about. I am quite sure that there must have been many smaller such events that have gone unnoticed. The evidence that they occurred in aggregate is there, but the individual events inevitably mostly remain unknown.
Sorry, I missed the point of all the Tunguska discussion that followed.
I think it highly likely, though, that such observations would be correlated today. If it was recorded by seismometers, it would have also been recorded by various high-precision gravitational experiments, and those guys are always trying to account for every speck of noise they can, which involves checking for correlations with basically everything they can think of.
For nuclear type events the monitoring is done with seismic equipment*. I am not sure how good the equipment would be at picking up ocean events but my best guess is that it would see them. I also don’t know how far along the monitoring network was back in 1979 but I will ask.
The folks doing the monitoring would probably not make it public. That would be a political decision.
These days I know that any sizable impact/explosion event will be caught using seismic equipment.
Slee
- My mom used to work in the group that did the monitoring.
As a matter of fact, I know of one right off the bat—the “2002 Eastern Mediterranean event,” which a little googling seems to indicate was rated at about 20kt explosive force, calculated by infrasound measurements.
Wikipedia also has a list of meteor air bursts, which should prove interesting.
While you’re undoubtedly right about the seismometers – there’s plenty of earthquake-watching going on – I’ll bet there’s no general correlating of microbarometer readings around the world, even today.
International Monitoring System (IMS) was mentioned up thread, it includes infrasound stations.
You may have misunderstood me. I wasn’t talking about geologists doing the correlating (though maybe they do; I don’t know them)-- The gravity folks themselves do correlating. And all of the gravity sites themselves have microbarometers, among many other instruments. Further, since many of the gravity researchers come from astronomy backgrounds, they’d probably take at least some interest in a source that appeared to be a large meteor impact.