Just now, theguru said:

I would think with no additional power source the waves would lose energy over time.  However, changes in the depth/structure should force the water up.  I need someone smarter than me to tell us what is what here. 

I agree with that. The question is how does the energy created by the volcano turn into momentum in the water and then how long does it maintain that energy before it loses momentum. Who is our physics member here on BGP?

27 minutes ago, Voice of Reason said:

I agree with that. The question is how does the energy created by the volcano turn into momentum in the water and then how long does it maintain that energy before it loses momentum. Who is our physics member here on BGP?

I did find this:

Did you Know?

Most tsunamis are not one big breaking wave that overruns the shore. They are usually a series of waves behaving similar to a rapidly rising high tide that can continue repeatedly over many hours, and even days.

 In most cases, the first in the series of waves is not the biggest. A tsunami may start small, relatively speaking, and develop over time. People have been killed most often by subsequent waves, coming hours after the “start of tsunami.”

Tsunamis travel faster over the open ocean than they do toward land. In the open ocean the travel a speeds of up to 600 mph, about the speed of a jet.

Not all tsunamis are recognizable by the fast recession of water from the shore. Only about 40% of tsunamis produce this natural warning sign.

https://www.caloes.ca.gov/cal-oes-divisions/earthquake-tsunami-volcano-programs/tsunami-about

And also this as a more specific answer to what we are talking about:

Tsunami waves in the deep ocean can travel at high speeds for long periods of time for distances of thousands of kilometers and lose very little energy in the process. The deeper the water, the greater the speed of tsunami waves will be.  

http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=1164&Itemid=2031

22 minutes ago, theguru said:

I did find this:

Did you Know?

Most tsunamis are not one big breaking wave that overruns the shore. They are usually a series of waves behaving similar to a rapidly rising high tide that can continue repeatedly over many hours, and even days.

 In most cases, the first in the series of waves is not the biggest. A tsunami may start small, relatively speaking, and develop over time. People have been killed most often by subsequent waves, coming hours after the “start of tsunami.”

Tsunamis travel faster over the open ocean than they do toward land. In the open ocean the travel a speeds of up to 600 mph, about the speed of a jet.

Not all tsunamis are recognizable by the fast recession of water from the shore. Only about 40% of tsunamis produce this natural warning sign.

https://www.caloes.ca.gov/cal-oes-divisions/earthquake-tsunami-volcano-programs/tsunami-about

And also this as a more specific answer to what we are talking about:

Tsunami waves in the deep ocean can travel at high speeds for long periods of time for distances of thousands of kilometers and lose very little energy in the process. The deeper the water, the greater the speed of tsunami waves will be.  

http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=1164&Itemid=2031

That last part explains why there is an alert for Hawaii and the US west coast and perhaps a bigger threat for them than New Zealand and Australia who are much closer to the volcano.

3 minutes ago, Voice of Reason said:

That last part explains why there is an alert for Hawaii and the US west coast and perhaps a bigger threat for them than New Zealand and Australia who are much closer to the volcano.

I am learning as I go here, explain that to me?

20 minutes ago, theguru said:

I am learning as I go here, explain that to me?

From your post, 

Tsunami waves in the deep ocean can travel at high speeds for long periods of time for distances of thousands of kilometers and lose very little energy in the process. The deeper the water, the greater the speed of tsunami waves will be.  

The waves will travel a long time over deep ocean to get to Hawaii and the US west coast and they will lose little energy over that trip. 

1 minute ago, Voice of Reason said:

From your post, 

Tsunami waves in the deep ocean can travel at high speeds for long periods of time for distances of thousands of kilometers and lose very little energy in the process. The deeper the water, the greater the speed of tsunami waves will be.  

The waves will travel a long time over deep ocean to get to Hawaii and the US west coast and they will lose little energy over that trip. 

I don't think that means that something that is closer would get less but I admit this is new to me.

7 minutes ago, theguru said:

I don't think that means that something that is closer would get less but I admit this is new to me.

I will add this part:

In most cases, the first in the series of waves is not the biggest. A tsunami may start small, relatively speaking, and develop over time. People have been killed most often by subsequent waves, coming hours after the “start of tsunami.”

What I am inferring (could very well be wrong) is when the first waves hit land earlier that creates a back force that takes energy/force/momentum away from the later waves. The shorter distance to New Zealand and Australia keeps them from experiencing the bigger tsunami.

In this article https://www.bbc.com/news/world-asia-60007119 they mention tsunami waves of 1 meter in Tonga and could go as high as 3 meters in Japan.

22 minutes ago, Voice of Reason said:

I will add this part:

In most cases, the first in the series of waves is not the biggest. A tsunami may start small, relatively speaking, and develop over time. People have been killed most often by subsequent waves, coming hours after the “start of tsunami.”

What I am inferring (could very well be wrong) is when the first waves hit land earlier that creates a back force that takes energy/force/momentum away from the later waves. The shorter distance to New Zealand and Australia keeps them from experiencing the bigger tsunami.

In this article https://www.bbc.com/news/world-asia-60007119 they mention tsunami waves of 1 meter in Tonga and could go as high as 3 meters in Japan.

I am not sure your inference is right but I don't know.  This basic fact from Google (and in many articles) would appear to make the opposite true but it also includes a time to prepare part of the calculation so that makes it a bit ambiguous to me:

Are distant tsunamis dangerous?

Local tsunamis, also called local-source tsunamis and near-field tsunamis, pose the greatest threat because tsunamis are most damaging near their source and there is little time to issue warnings and evacuate. ... Distant tsunamis can also have significant impacts on coastal communities.

===============

I do think it makes good common sense that the nearer you are to the source the worse it will be but again I am not sure here VoR.
 

One thing for certain.  If the sea recedes out - take to high ground. 

This is Chile at least a couple of hours ago: 

 

 

 

From Foxnews.com and NPR:

The eruption was 600 times more powerful than the atomic bomb dropped on Hiroshima, according to scientists. NPR reported that the eruption was likely one of the loudest events to occur on the planet in 100 years and could be heard in Alaska.

On 1/15/2022 at 12:14 PM, Bluegrasscard said:

Some photoshop showing if this was where Mt. St. Helens is. 

 

 

Jeez….that would cover both Oregon and Washington!! 
 

There was an eruption in Indonesia in 1883 of Mount Krakatoa that killed 36,000 thousand and so much dust and debris was emitted into the atmosphere that it caused temperatures to drop worldwide and a shortage of crop production for a couple of years. The sound waves from the explosions traveled around the earth seven times and it was heard in a 2000 mile radius.