The powerful earthquake that struck Sumatra, Indonesia, in the last week of March hastened the completion of the development of a sophisticated system, which must be sunk into the depths of the ocean, and whose role is to provide early warning of potentially devastating giant earthquakes
The powerful earthquake that struck Sumatra, Indonesia, in the last week of March hastened the completion of the development of a sophisticated system, which must be embedded in the depths of the ocean, and whose role is to provide early warning of potentially devastating giant earthquakes. The system was developed at the Woods Hole Oceanographic Institution and the University of Southern California. It is supposed to detect small seismic shock waves, or what is also known as foreshocks - preliminary shocks that herald the arrival of a large earthquake.
The developers of the system believe that they have an effective device for warning a few hours before a powerful earthquake occurs on the seabed. In contrast to continental earthquakes that are not accompanied by foreshocks and therefore cannot be predicted in this way. An earthquake that is focused in the depths of the ocean and may cause a tidal wave, tsunami, destructive, is characterized by a foreshock. And for this reason, the scientists from California explained, their system is effective.
In a study that accompanied the development, Jeffrey McGuire of the Woods-Hole Institute found that the tectonic plates in the eastern Pacific Ocean are moving apart at a rate of 10 cm per year from each other. The movement could cause an underwater earthquake. McGuire and his team used sensors from the Oceanic and Atmospheric Administration and the Marine Environmental Quality Laboratory that pinpointed the time and location of those foreshocks that heralded the appearance of the very strong earthquakes that followed some time later. Contrary to the popular approach that earthquakes occur suddenly and without warning signals and therefore cannot be predicted - in this case it turned out not to be the case.
A foreshock is calculated to be at least 2.5 on the Richter scale - as a signal that was followed by an earthquake of at least 5.4 on the scale and of course greater. The sensor provided an advance warning of one hour, for a radius of 15 km from the center of the noise. In an experiment to examine the effectiveness of the early warning system, conducted by the research team, success was achieved in predicting six out of nine powerful earthquakes. In particular, the effectiveness was recognized when it comes to earthquakes in the middle of the ocean, far from populated areas.
McGuire believes that placing the next generation of warning systems in the depths of the seas will indeed achieve its goal. A re-analysis of data accumulated from the largest recorded earthquake - 9.5 on the Richter scale in 1960 in Chile - revealed that a sensitive sensor was able to provide about 15 minutes advance warning before it erupted at its most powerful. And all this on the basis of those preliminary tremors. Only in 2007 will the state-of-the-art sensors developed by McGuire begin to be placed and "planted" in the eastern Pacific Ocean.
How much do tsunami damages amount to?
The tsunami disaster in South-East Asia - the enormous dimensions of carnage and destruction - initiated a series of new studies dealing with the destructive natural phenomenon. Scientists in the USA, for example, hastened to calculate that a tsunami event of a similar magnitude, if it had hit Southern California, especially the Los Angeles area and resort towns in its vicinity, which have long been defined as due for this - the property damage dimensions would amount to 42 billion dollars. A really imaginary amount.
This is the first time that scientists try to calculate in monetary terms the possible losses and damages from tsunamis - and this separately from damages that may be caused by an earthquake.
The research done at the University of Southern California and published in this month's issue of the Monthly for Civil Engineering found that a huge tidal wave (tsunami) following a huge earthquake and the underwater collapse of unstable soil layers that the Palos Verdes Peninsula in California is characterized by - could wreak havoc on unknown dimensions To this day.
The study identified the most prominent risk areas: the Ports of Los Angeles and Long Beach (now Marina), all the coastal cities of Orange County and large areas of Los Angeles itself - a total of 308 sub-regions that all contribute to the California economy and have connections economic with additional geographic areas.
The authors of the study, led by Prof. Jose Borrero and his colleague Prof. Costas Sinoulakis, stated that they deliberately avoided any attempt to assess the dimensions of the harm to the soul in such a catastrophic event, which would also have required them to calculate the value of life from an economic point of view.
So they took a different approach: the researchers described four possible disaster scenarios, with the most extreme and worst even requiring the closure of all highways leading to California for at least a year - which would have caused a significant loss of revenue from transporting goods with a total value of 83 billion dollars.
The study also found that the Long Beach area, whose beautiful marina hosted the 1984 Olympic sailing events, probably suffered the most damage - estimated at $3.6 billion, more than any other city or town.
And "normal" wave damage
Today there is a clear tendency in quite a few scientific institutions to provide data from innovative studies that concern the preservation of the environment from destruction - of nature or of man. The ocean waves hitting the coastlines of many cities, for example, are a threat that is now being investigated.
The Faculty of Engineering team at the University of Liverpool is now carrying out such a study, the purpose of which is to reduce the threat to homes and property from the waves of the Atlantic Ocean. About ten percent of the inhabitants of Great Britain live near the coastal areas where there is a risk of floods and the destructive process of the coastline, due to the waves of the sea. The problem is that a significant part of these coastal areas lack suitable breakwaters. Already today, the annual damage to property, roads and paths in the coastal areas in Great Britain reaches 2 billion pounds.
In order to provide an answer to the ever-increasing problem, Dr. Terry Hedges from the Faculty of Civil Engineering at the University of Liverpool initiated a study based on a computer model that estimates the amount of water that manages to breach breakwaters. The study examined whether following the construction of the breakwater, the waves are higher than before and manage to pass over the surface of these "sea walls", which causes floods every winter and the destruction of property and not once also takes a toll on human life.
The model will suggest ways to reduce the dimensions of the destruction and damage and also what measures should be taken - that is, to build - in order to protect the lands and buildings.
The model, the first of its kind at a world level, will allow researchers to initiate different scenarios, complex and integrated situations of natural events - which are a danger to vehicles, pedestrians and buildings as well as to the breakwaters themselves. It will make it possible to predict exactly what damage is caused by waves at a certain height - and based on this to propose proactive road closures when there is a forecast for a severe weather event. All this, in order to reduce the dimensions of the destruction, to evacuate residents ahead of time to shelter areas - and also to initiate the thickening of breakwaters and "marine protective walls" in preparation for a particularly rainy winter.
A calculation already carried out using this model revealed that the construction of a special marine defense system on the coastline - those walls and breakwaters at an appropriate height - is a very expensive project. Construction of 1 km of sea wall will cost about 10 million pounds (about 80 million shekels). The authors of the study promised to find advanced engineering ideas that would enable the construction of such protective walls efficiently and at appropriate pricing.
How important this issue is can be learned because scientists from Japan and Portugal joined the research project - and there is a promise that the findings will be provided to any country in the world that needs them for protection against a possible natural disaster.
