How Telescopes Deal With Earthquakes In Chile

Reader edgeofphysics provides a technical sidelight on 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 in the world, how do astronomers protect their giant telescopes that have been built or are being built in the Chilean Andes? This blog post discusses how Chile's most advanced facility protects its priceless 8.2-meter primary mirrors in the event of an earthquake."

Comments

Bubble Wrap?

[WrongSizeGlass]

Lots and lots of bubble wrap?

Re:Bubble Wrap?

[sopssa]

Lots and lots of bubble wrap?

Which have been all popped by the scientists.

Re:VLEC - Very large egg cartons

[Anonymous Coward]

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.

There now no one needs to RTFA.

Re:VLEC - Very large egg cartons

[phantomfive]

moderate quakes, of less than 7.75 Richter

Only in Chile would a 7.75 earthquake be considered 'moderate.' Smaller earthquakes have devastated Haiti, Turkey, Taiwan, El Salvador, and parts of the US, India and Pakistan (and pretty much anywhere else such an earthquake has happened).

Re:Better than

[HornWumpus]

Richter scale is a useful measure for geologists as it measures the approximate total energy released in the quake on a log scale.

Structural engineers on the other hand measure earthquakes mostly by maximum G load incurred and the type of waves.

Long duration earthquakes (as this one appears to be) are generally less destructive then they would appear based only on their Richter rating.

More data is sure to come regarding the peak intensity of shaking.