News from the Frontiers of Cosmology: A companion to the book The Edge of Physics
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Chile earthquake and telescopes

How giant telescopes in Chile are protected against earthquakes

How giant telescopes in Chile are protected against earthquakes

The latest earthquake to hit Chile was located near Concepcion, just south of Santiago.

Sadly, early reports of fatalities are emerging. In addition to the unfortunate loss of lives and livelihoods, Chile has to worry about something that is of interest to the astronomical community: telescopes.

Given that Chile is one of the most seismically active in the world, it’s a wonder that the country hosts some of the most powerful telescopes on the planet. These include the European Southern Observatory’s Very Large Telescope (VLT) in Paranal, Chile. It’s high in the Chilean Andes, about 1600 kilometres from Santiago. Even the planned 42-metre European Extremely Large Telescope is most likely going to be built in Chile.

Eyewitness reports on the BBC say that the Concepcion quake was felt as far away as Pergamino, Argentina, 200 kilometres north of Buenos Aires and about 1800 kilometres from quake’s epicentre.

So, most likely, ESO’s facilities on Mount Paranal would have felt the quake.

The four 8.2-metre telescopes that make up the VLT are well equipped to deal with earthquakes. Here’s a paragraph from The Edge of Physics that describes how the primary mirrors of the VLT are protected when the Earth shakes:

  • The primary mirror is 18 centimeters thick. Because of its weight, the mirror’s precise shape can warp when it is tilted, so 150 actuators, upon which the mirror rests, continually push and pull at least once a minute to ensure that the optimal curvature is maintained. More impressive than the actuators are the clamps around the edges of the mirror, which can, at a moment’s notice, lift the entire mirror, all 23 tons of it, off the actuators and secure it to the telescope’s support structure in case of an earthquake (moderate quakes, of less than 7.75 Richter, are not uncommon here, thanks to the ongoing collision of the Nazca and South American plates). The entire telescope is designed to swing during an earthquake, and securing the primary mirror prevents it from rattling against the metal tubes that surround it.

To see the 8.2-metre mirror and the actuators, click here for pictures (the mirror is the seventh in the slideshow).

The Edge of Physics


1 Greg { 02.27.10 at 10:50 pm }

A 7.75 quake is considered a major quake. Moderate is used to describe earthquakes from 5.0 to 5.9.

2 Felipe Budinch { 02.28.10 at 2:08 am }

I’m in Santiago using Internet, drinking a glass of coke, eating something out of my fridge. We are used to this kind of events ;-)

There are going to be very little casualties, I’m guessing less than 1000. (I know it is still awful, because unlike telescopes, human life is priceless, but it could be worse if we were not prepared)

3 Super Dave { 02.28.10 at 3:04 am }

Possibly a 7.5 should be described as major, not moderate.

4 Chile earthquake and telescopes | { 02.28.10 at 3:14 am }

[...] See more here: Chile earthquake and telescopes [...]

5 uberVU - social comments { 02.28.10 at 3:43 am }

Social comments and analytics for this post…

This post was mentioned on Twitter by micobit: how do astronomers protect their giant telescopes. #terremotochile…

6 sthapit { 02.28.10 at 4:26 am }

@greg – maybe a 7.5 is moderate for chile?

7 Beryllium { 02.28.10 at 5:59 am }

I suspect that Chile may operate on a slightly different graded scale, what with being home to the largest recorded earthquake in modern times …

8 JohnM { 02.28.10 at 8:11 am }

If you search the internet for Earthquake and telescope you will find a number of references to the damage caused ny the earthquaqu in Hawaii a few years ago. In most cases the damage was due to the telescope moving on the oil bearings but the oil was not on. Also damage to the dome rollers of the CFHT. Nothing major I think they were all operating again in a week or two.

9 JohnM { 02.28.10 at 11:14 am }

The other thing that I forgot to mention was that a number of hard discs failed – I presume the platter hit the heads when they were vibrated by the quake.

10 How Telescopes Deal With Earthquakes In Chile | JetLib News { 03.01.10 at 9:44 am }

[...] the earthquake in Chile this morning — some details on how the European Southern Observatory protects the mirrors of the Very Large Telescope when an earthquake strikes. “Given that Chile is one of the most seismically active countries [...]

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