Improving Tsunami Warning Systems

I do agree that all systems should be regularly reassessed from time to time to look for improvements. While this short teaser introduction does not state that the tsunami warning system failed, there is an implication there. That offends me.

The Christmas tsunami of 2004 was not detected before shore impact mainly because of a lack of sensors, but also because this is a relatively new field of study. Because this field is new, we do not know how much and what type of data is required to be able to do accurate predictions. Technically, we don't know if it can be predicted at all. But the recent immense Chilean earthquake was the fifth largest recorded earthquake in the past 110 years. Sensors in the Pacific did detect a tsunami propagating across the ocean. The scientists quickly and as accurately as they could issued a tsunami warning. The fact that the resulting wave was in the lower end of their prediction range should not be portrayed as a failure but as a success. They did predict the size of the wave.

I hope that your article gives these people the credit that they are due. They successfully did exactly what they were charged to do. I also realize that eye catching headlines are what draws readers to an article. But please don't imply that a success was a failure here. It demeans the capability of the scientists trying to save lives and it lowers the status of this website.

From a railroader's perspective.

First I want to say - I hope the folks who sounded the alarm will not hesitate to do the same thing again given the limited data they had to work with. As importantly, I hope the folks affected understand the importance of erring on the side of caution.

Investment in the technologies that would give us quick approximations during these events would also give us the platforms for doing other science. It would be money well spent.

I believe that an Earthquake Tsunami is caused by the vertical displacement of the earths crust along a subduction zone where there is uplifting of the overlaying crust. That an earthquake along a sliding fault would not cause the same displacement of water even given that an equal amount of energy may be dissipated.

It seems reasonable that in order to determine the total energy of the wave event, sensors along the fault must determine the depth of the water, the area of the affected crust, and vertical displacement of the crust in order to approximate the energy of the wave. The total energy of the wave generated would be proportional to those three variables. The power of the wave would also be a function of the rate of vertical displacement during the event.

In calculating the danger of the Tsunami relative to distance from epicenter, total hydraulic energy would not seem to be the only variable. It would seem that the length along the fault of the uplifting would affect the time and displacement rate of energy distribution as the water volume moved away from the point of disturbance. I would guess that the hydraulic energy would distribute more slowly, relative to distance, along a long wave front than a short wave front given equal hydraulic energy. Although the vertical water column would be initially higher in the short wave front for any given hydraulic energy, my intuition tells me that the energy of a water column in a short wave front would distribute more quickly as the wave front moved away from the fault.

In short; it seems that an approximation of Tsunami danger would require more than just sensing the change in the height and distance between wave peaks at a few points along the path of the Tsunami. Some approximation of both total wave energy and length of displacement along the fault displacement would be required.

A couple of things that come with this consideration are:

Is a major oceanic conveyer strong enough to affect the energy transfer across the conveyer as the wave front passes?

How would the angle relative to the conveyer affect the energy transfer?

How would the Tsunami energy affect the conveyer and vise versa?

What would be the difference if the disturbance is caused by subduction instead of uplifting?

Are there any experts out there willing to share there expertise with us?

Gavilan

I believe a network of sensors and satellite images with good computational model can predict much better the likely damage that may happen on any coastal site. Simple wave motion at some point may be a very local phenomenon and that may give a wrong warning or no warning at all. If current starts below the surface level then also it may go undetected.