Mt st helens

[oldman420]

was anyone in Portland or Vancouver when mt st helens went off last time?
If you were did you hear it?
how far would the sound and vibration travel from a megaton size ground explosion?

 

[DrPizza]

The vibration would travel through the earth to just about anywhere (see exception below). It would be detected by the same equipment that senses earthquakes (because, basically, that's what it is). If I'm not mistaken, there are a variety of waves emitted including the body waves passing through the earth: p and s waves. The p-waves travel faster than the s-waves. P-waves are longitudinal waves, so they'll travel through liquids as well. S-waves are longitudinal waves that don't travel through liquids. The s-waves aren't detected everywhere, providing evidence for a molten layer in the earth as well as serving to help find large oil deposits.

 

[Geforce man]

i went to see the actual site not but 2 years ago, and it was beautiful and aweful at the same time. the level of destruction that it brought about was truly amazing, and i honestly hope that it never happens again. but if it does, i hope that the people at or around there are getting out of there.

 

[D1gger]

I live in Victoria BC and was woken up by the blast the last time Mt. St. Helen blew her top. I woke up thinking that someone had fired a cannon a few blocks away. At the same time, my parents happened to be traveling in Washington state, and were having breakfast in a dinner that had a view of the mountain, they watched the ash cloud for a few minutes and then decided they better get in the car and move away before they got caught in the fallout or in the traffic jams sure to follow.

Most memorable.

 

[DrPizza]

It's something I would love to witness - from a safe distance.

 

[Subhuman25]

I live nearby and Hwy 504 leading up to the Johnston Observatory and the Windy Ridge acces road are some of my favourite "canyon racing(motorcycle)" roads here in Wa. state.
I live on the epicenter of the last big earthquake we had here a couple years ago.Mt. St. Helens wouldn't bother me so much blowing,wich it will,but god forbid if Mt. Rainier blows it's stack.The loss of life and material damage would be astronomical.

 

[Gamingphreek]

A little OT but how did the area fair where you lived at that time? You said you guys left was everything intact when you got back or...

Also what is taking it so long, it was like blowing smoke and ash a few days ago now its just sitting there.

-Kevin

 

[oldman420]

I think it is going to erupt big time and at minimum spew large amounts of ash.

 

[ChuaChua]

On a side note, do you guys know if Mt.St. Helen's eruption could possibly trigger another earthquake somewhere nearby? Loosening the earth and whatnot.
Here in Vancouver, BC, we are near the Cascadia subduction zone, and we are supposedly way overdue for a big earthquake, called The Big One.
I am not sure if Mt.St.Helen's eruption has a big enough effect on the surrounding plates and stuff.

My first post on the Highly Technical post

 

[dkozloski]

Not to worry, compared to previous events such as Krakatoa, and Mt. Katmai, St. Helens is pretty small potatoes and we're all still here. Krakatoa put so much stuff into the air in 1883 that the earth's climate was affected for five years. St. Helens ejected about 2.8 cu.km. of dirt and rock and Mt. Katmai ejected about 35cu.km.of ash. St.Helens erupted for nine hours and Mt.Katmai erupted for 60hrs. The biggest difference is that St.Helens was on TV and is all people are aware of nowdays. For my money the Lituya Bay event in Alaska in 1958, not to be confused with the good Friday earthquake, was much more impressive. A force 8.1 earthquake centered at the head of Lituya Bay near Yakatat caused 90,000,000 tons of rock to drop into the bay from a mountain. A wave 1720 feet high was generated that swept down the bay toward the Pacific Ocean at over 100 MPH. Three fishing boats were in the bay. One was lost with all hands, another capsized but the people saved , the third rode the wave 25 miles out to sea. All vegatation and soil was cleaned off a mountain to an elevation of 1720 ft. to leave positive proof of wave height. In order for the survivors to see what they reported when the rock dropped, land screened out by a hill had to have momentarily changed elevation 50 ft. and returned to its original position. Geologists say it is vey likely to happen again.