# Number of Waves/Crests in Tsunami Wave Train

• morrobay
In summary: It looks to me that at least there is no clear cut answer to your question.Ok well I just don't know, I am a mathematician that knows something about classical wave theory but I am no expert in water waves and tsunamis. Just wait a little longer, maybe this thread will attract the attention of more people and possibly some experts. It looks to me that at least there is no clear cut answer to your question.One wave can have multiple crests, but each crest is not necessarily a separate wave. In the case of a tsunami, the seismic event may produce multiple crests, but they are all part of the same wave. Therefore, in the scenario described, there would be one wave that hits the beach, with
morrobay
Gold Member
Homework Statement
An event 1600km offshore produces a Tsunami. Wavelength= 200km Velocity = 800km/hr. How many waves in the wave train ?
Relevant Equations
k= 2pi/wl = .0314 radians. T = wl/v = .25 hr. w = 2pi/T = radians/hr.
In the two hours the wave is traveling from event 1600km offshore to land would eight waves/crests be produced: 2hours/T=15minutes be correct ? Eight cycles = eight waves in the train. * I asked on another physics forum. No reply. "Tried" to register on several oceanography forums.

Delta2
morrobay said:
Homework Statement:: An event 1600km offshore produces a Tsunami. Wavelength= 200km Velocity = 800km/hr. How many waves in the wave train ?
Relevant Equations:: k= 2pi/wl = .0314 radians. T = wl/v = .25 hr. w = 2pi/T = radians/hr.

In the two hours the wave is traveling from event 1600km offshore to land would eight waves/crests be produced: 2hours/T=15minutes be correct ? Eight cycles = eight waves in the train. * I asked on another physics forum. No reply. "Tried" to register on several oceanography forums.
I think you are correct. With the given data the period is indeed 1/4 of an hour and within the two hours it does to travel to the shore, there will be ##8=\frac{2}{\frac{1}{4}}## full waves produced.

It was just a bit vague the way you stated the problem, asking just for the wave train. You meant the wave train that is formed, till the tsunami hits the shore.

PS. Then again, there is something fishy here. If we going to take it that 8 full waves are produced within 2hours this means that the seismic activity that produces the tsunami continues for 2hours as well, which I don't know if it is something valid.

Last edited:
Delta2 said:
I think you are correct. With the given data the period is indeed 1/4 of an hour and within the two hours it does to travel to the shore, there will be ##8=\frac{2}{\frac{1}{4}}## full waves produced.

It was just a bit vague the way you stated the problem, asking just for the wave train. You meant the wave train that is formed, till the tsunami hits the shore.

PS. Then again, there is something fishy here. If we going to take it that 8 full waves are produced within 2hours this means that the seismic activity that produces the tsunami continues for 2hours as well, which I don't know if it is something valid.
The seismic event can be only seconds duration. What continues for 2 hours are all the waves produced reaching land. The first wave reaches land in two hours then every 15 minutes waves 2 through 8. So a total of four hours for the complete wave train . Again this is assuming that each cycle is a wave. And all above is not taking into account the change in velocity with ocean depth. An oceanographer would be required for an exact answer accounting for all the variables . I am just asking for the standard conditions answer.

https://ocean.si.edu/planet-ocean/waves-storms-tsunamis/anatomy-wave

morrobay said:
What continues for 2 hours are all the waves produced reaching land
Sorry I am not an oceanographer but I can't understand how the seismic event can be only seconds, but waves will be produced for 2 hours...

This is the original question. Does each of the eight cycles constitute a wave. Or is it one wave with eight cycles.

morrobay said:
This is the original question. Does each of the eight cycles constitute a wave. Or is it one wave with eight cycles.
I don't very much understand the question. It's more or less the same thing to me.

Delta2 said:
I don't very much understand the question. It's more or less the same thing to me.
Will one wave hit beach or eight waves. Seems now one is correct

morrobay said:
Will one wave hit beach or eight waves. Seems now one is correct
If eight waves are produced then eight will hit the beach, I just doubt that all eight are being produced since the source is active only for a few seconds. I have an analogy in mind, when a stone falls into the surface of a pool then the collision lasts only for a few milliseconds but only one or two full waves are produced I think.

morrobay
Delta2 said:
If eight waves are produced then eight will hit the beach, I just doubt that all eight are being produced since the source is active only for a few seconds. I have an analogy in mind, when a stone falls into the surface of a pool then the collision lasts only for a few milliseconds but only one or two full waves are produced I think.
These are photos of a video I made that uploads but cannot post. One rock dropped into the pool produced multiple waves.

Delta2
Ok well I just don't know, I am a mathematician that knows something about classical wave theory but I am no expert in water waves and tsunamis. Just wait a little longer, maybe this thread will attract the attention of more people and possibly some experts.

morrobay

## 1. How many waves are in a tsunami wave train?

The number of waves in a tsunami wave train can vary, but typically there are 3-5 large waves that make up the train. However, there can also be smaller waves in between the larger ones.

## 2. Why are there multiple waves in a tsunami wave train?

Tsunami waves are created by a disturbance in the ocean, such as an earthquake or underwater landslide. The initial disturbance can create a series of waves that travel together, forming a wave train.

## 3. Do all tsunami wave trains have the same number of waves?

No, the number of waves in a tsunami wave train can vary depending on the strength and location of the initial disturbance. Some wave trains may have more or less waves than others.

## 4. How far apart are the waves in a tsunami wave train?

The distance between waves in a tsunami wave train can range from a few minutes to over an hour. The time between waves is determined by the speed of the waves and the distance they need to travel.

## 5. Can the number of waves in a tsunami wave train be predicted?

While scientists can predict the approximate number of waves in a tsunami wave train based on the initial disturbance, it is difficult to predict the exact number and timing of the waves. This is due to the complex nature of ocean currents and the potential for secondary disturbances to create additional waves.

Replies
18
Views
2K
Replies
20
Views
3K
Replies
3
Views
3K
Replies
4
Views
2K
Replies
21
Views
13K
Replies
7
Views
7K
Replies
20
Views
2K
Replies
7
Views
3K
Replies
7
Views
1K
Replies
38
Views
9K