Chilling Chile Christmas quake

Update: No deaths reported, but it did some damage.


Original:

I receive earthquake alerts on my phone and this is the largest I’ve seen in a while. An alert says hazardous tsunami waves reaching 1 to 3 meters (9.8 feet) above the tide level are forecast for some coasts in Chile. 


An earthquake at 7.9 on the Richter scale is a big deal, causing potentially up to 1,000 deaths.


Historical data shows that there have been bigger quakes for Chile, including an 8.3 in 2015. 

The Richter magnitude scale (also Richter scale) assigns a magnitude number to quantify the size of an earthquake. The Richter scale, developed in the 1930s, is a base-10 logarithmic scale, which defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude, as recorded on a standardized seismograph at a standard distance.

As measured with a seismometer, an earthquake that registers 5.0 on the Richter scale has a shaking amplitude 10 times greater than an earthquake that registered 4.0 at the same distance. An increase of 1 magnitude corresponds to a release of energy 31.6 times that released by the lesser earthquake. For instance, an earthquake of magnitude 5 releases 31.6 times as much energy as an earthquake of magnitude 4.

Magnitude 3 = 2 gigajoules

Magnitude 4 = 63 gigajoules

Magnitude 5 = 2,000 gigajoules

Magnitude 6 = 63,000 gigajoules

Magnitude 7 = 2,000,000 gigajoule

At 7.9, this quake released 45  petajoules (PJ) of energy or the equivalent of a 10.7 megaton  bomb. This is on the level of the energy of the Tunguska event.

For reference, a petajoule (PJ) is equal to one quadrillion (10^15) joules. The Tsar Bomba, the largest man-made nuclear explosion ever, released 210 PJ which is equivalent to about 50 megatons of TNT. 

Tsar Bomba was the Western nickname for the Soviet RDS-220 hydrogen bomb, the most powerful nuclear weapon ever detonated. Its test on October 30, 1961, remains the most powerful human-made explosion in history. Link

Here are some other interesting energy comparisons (PDF).

The damage based on the scale is only slightly predictable as depends on what is hit. For example, a 7.9 quake that once hit Alaska did not cause any deaths.

Good luck to those in Chile this Christmas Day, 2016. Stay safe. 

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