Tsunami numerical modelling and simulations

Tsunami Numerical Modeling

Tsunami Modeling

Tsunamis, along with other massive natural disaster events such as earthquakes, hurricanes and so forth, represent one of the most (if not the most) destructive natural disaster event that has occurred in the past or that could occur in the future. They typically coincide with earthquakes in a given area but accurately predicting and projecting when they will occur, when they will not occur and the methods of predicting both has become a fairly chaotic and fickle endeavor. However, the use of computer and numerical-based modeling has represented a shift in that it can more accurately predict what will or will not occur when earthquakes and other conditions relative to tsunamis occur and avail themselves to geologists, oceanic experts and other scientists that are the least bit involved in predicting tsunamis and warning the populace around the world about the same. After explaining the data sources and methods, this repot will cover how to predict and account for damage scenarios, the areas of the world that tsunamis typically occur in, what happens when tsunamis make landfall, what patterns have become clear over time, what areas are more vulnerable than others, and particular tsunami events in the past, mostly in the 1950's, that have illuminated the subject quite effectively.

Materials & Methods

The materials and methods to be used for this brief literature review, methodology and results/discussion treatise are fairly basic. Of course, the main topic at hand is tsunami and the "drill down" on the subject has been and will be on how numerical models can be used to explain why things happened a certain way in the past and how that data can be used to predict similar events or close calls in the future. The materials used include ten different professional or peer-reviewed journals that relate specifically to modelling of tsunami prediction and handling, historical analysis, future predictions or a combination of the three. After assessing the ten sources, there will be a synthesis of what was reviewed and the relevant points that can or perhaps should be captured from the material.

Results

Overview

Perhaps the best way to learn future lessons is to look exhaustingly and complete at prior events and happenstances to see what can or should be learned. There was a nasty tsunami in 1956 that affected the area of Greece. One of the ten articles reviewed for this literature review and results summary reflect that the disaster was recorded and assessed from nearby Yafo, Israel. This was far from the first such event in that area as there were 300 descriptions of tsunamis or at least something very similar over the decades and centuries. Of course, scientific standards and measurement methods were paltry or were not even attempted back in the 1950's and before. However, this does not mean that something cannot or should not be learned from those experiences. Frustratingly, most of the accounts that were ever offered were based on simple eye-witness accounts and little to anything else. Even so, the fishing buoy gauges that existed at the time reflected that Yafo and nearby Greece got creamed by a tsunami in 1956. The tsunami started at 0900 hours local time in Israel and lasted about twelve to fifteen minutes (Beisel et al., 2008). The Greek account of the same event yielded similar results. The tsunami was ostensibly the result of an earthquake and caused swells of thirty, twenty and ten meters in height. Updating modeling since then has relocated the epicenter and genesis of the earthquake that led to the tsunami and has led to a modeling crafted after the fact even though the event was more than half a century ago and before modern scientific methods were or could be employed (Okal et al., 2009).

Tsunami modeling of any sort, numerical or otherwise, is not remotely an exact science yet but the hotspots and the amount of warning time involved is fairly clear. One such hotspot can be found in the eastern Corinth Gulf along the Perachora Fault in the area of Greece, the same area just mentioned in the prior paragraph (Tselentis et al., 2006). Further, the "hotspots" in question have been so for many centuries or even multiple millennia. For example, it is commonly held that the Greece area has been a hotbed of tsunamis for more than 3,500 years. While the data set is very wide open, the amount of time that proper and effective scientific measurements have existed has been quite narrow. However, it is still easy to state that some areas Gulf of Corinth are very tsunami-genic areas of the world given the fault line that exists, the topology of the ocean floor and the arrangement of the nearby coastlines and other geography (Papathoma & Dominey-Howes, 2003).

One reason numerical models would be superior to prior accounts is that only about a third of prior reports over all of history could be tied to primary sources. However, numerical modeling from data that is knowable and verifiable could lead to more emphatic and conclusive data and the information that is provable from prior incidents, no matter how far back in the past, can be used to assist in the same (Salamon et al., 2008). For example, it is widely known nowadays that a thick water layer is necessary to make tsunamis possible and nasty and that is something only seen in ocean waters (Tselentis et al., 2010).

What can and does prove the efficacy of numerical models is geo-scientific evidence as compared to those models. The computer and numerical modeling is driven by the topographic and bathymetric data that is collected pre- and post-tsunami. One such data set that has been used involved fifteen scenarios for five different grades of intensity using software known as AnuGa, short for Australian National University along with Geoscience Australia. The science is still very much in its nascent stages. This is proven by the fact that some warnings, even in hotbed areas, turn out to be false alarms. However, to not try and/or to not warn people about the possibility is a non-starter so the models need to be used as much as they can be given the data that is known to exist and be true and the models can be improved over time (Floth et al., 2009). Worst case scenarios are of the focus of research but these scenarios usually do not come to pass even when an earthquake occurs in the tsunami hotbeds and/or a tsunami warning is issued. Again, using prior events and facts are useful but correlating that to predicting future events has been elusive and the former is far and away the more effective method at this time (Mitsoudis et al., 2011).

Of course, simple mathematics and numbers are sometimes hard to correlate to real life and it could somehow come down more to odds, probability or likelihood rather than whether it will definitely happen or not. However, this could change over the coming decades as data becomes less anecdotal and non-scientific and more science-based (Papadopoulos et al., 2007). Over time, scenarios and guesses will become more concrete through better modeling and prior data that is more completely collected and observed (Tinti et al., 2011).