Beirut Explosion Thread...

The Beirut Explosion registered as a 3.3 Magnitude Earthquake.

The vibrations appear to have reached our area between 2-3pm CDT and were recorded on seismographs all across Arkansas.

(Squiggly lines towards the top) /1

It's not directly comparable to an Earthquake because this shockwave was generated at the surface instead of underground.

The travel time between the explosion and when the vibrations reached Arkansas was about 4 hours. /2

The distance is roughly 6,500 miles; meaning waves were propagating in the neighborhood of around 1,600mph.

This makes sense considering the shockwave of a similar sized nuclear explosion would generate a shockwave moving at 2,000mph tho air would be faster than water or land/3

There are similarities but also many differences with an Earthquake vs Explosion.

Since this occurred at the surface it might be easier to think of the Earth as a huge cymbal and the vibrations like a stone striking it and reverberating back and forth. /4

The p-waves (think "pressure") travel fastest and can pass through solids and liquids, s-waves (think "shear") get absorbed by the mantle but travel slower along the Earth's crust. /5

A surface explosion wouldn't have generated much energy downward but instead radially in all directions which would explain the lack of seismicity locally in the moments immediately following the blast but would account for the slower s-waves that arrived hours later./6

The location is also interesting from a geologic standpoint.

The Mt Lebanon Coastal Range is the site of an active thrusting fault line that's thought to have a recurrence interval of about 1,500 years. /7

The last major Earthquake generated a massive tsunami in 551 AD that would have flooded most of the region... at that time known as Phoenicia (where the color purple came from; the name Phoenicia means "land of purple") /8

When the fault slipped back then it thrusted between 5-10ft
of earth vertically releasing a tremendous amount of energy; probably comparable to a 7.5 moment magnitude according to research of the geophysical data in that region. /9

Would an explosion generated by mankind be enough to cause dormant faults to become active again? Sure, but depth is key and this occurred at the surface. /10

That said, if the last big one was in 551 AD and the recurrence interval is around 1,500 years... it's certainly enough to give one pause. /11

It is 2020 after all.

/Final