Earthquake is a frightful thing that everybody is afraid. Think of a situation under which a big earthquake has struck your town suddenly, the casualities involved , the damages to the houses, roads, the disruption of communication system and other things like the total breakdown of water supply and important infrastructure. The intensity of suffering by the victims is getting worse and worse day by day because of the slow relief and rescue efforts.
Most of the largest known earthquakes have been centered around the Pacific’s Ring of Fire. It is estimated that 90% of the world’s earthquakes take place within this Pacific’s Ring of Fire. Among the world’s 25% of the largest earthquakes, 3 of which are from this area of the Ring of Fire in the last 11,799 years .The Ring of Fire is the direct result of tectonic plates, which are the distortion of earth‘s crust due to forces within it and the movement and collision of the lithospheric plates which are the outer layer of the earth’s crust. These plates which constitute the outer layer of the planet Earth, are constantly in motion atop the mantle [the part of earth between the crust and the core] .Sometimes they collide, pull apart or slide alongside each other ,resulting in creating convergent boundaries, divergent boundaries and transformed boundaries, hereby resulting in an outbreak of earthquake of small or great magnitude.
It is common knowledge that earthquakes are usually caused when rocks underground suddenly break along a fault.This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rocks or two plates are rubbing against each other or when two blocks of the earth suddenly slip past one another, the surface where they slip is called the fault, which resulted in an earthquake.
Countries lying within the Pacific’s Ring of Fire are shown as below:-
8 , Japan
9, New Zealand
10, Papua New Guinea
The loss of lives and properties from big earthquakes has given a hard hit to the Governments that were encountered by the disasters. Therefore, the governments are searching for clues to be able to predict early signs of earthquakes in order that they can issue early warning of the potential outbreak of damaging earthquakes to take timely response to the disasters, enabling people to minimize loss of lives and properties. The U.S has conducted field , laboratory and theoretical investigations of earthquake mechanism and fault zones. Ultimately, scientists would like to be able to specify a high probability for a specific earthquake on a particular fault within a particular year. Scientists estimate earthquake probability in two ways by studying the history of large earthquakes in a specific area and by finding out the rate at which strains accumulate in the rocks.
If a region has expressed four magnitude 7 or larger earthquakes during 200 years of recoded history ,and if these shocks occurred randomly in time, then scientists would assign a 50 per cent probability
[that is just as likely to happen and as not to happen ] to the occurrence of another magnitude 7 or larger quake in the region during the next 50 years. But in many places, the assumption of random occurrence with time may not be true because the strains are released along one part of the fault system. It may actually increase another part. Four magnitude 6.8 or larger earthquakes and many magnitude 6—6.5 shocks occurred in the San Francisco Bay region during the 75 years between 1836 and 1911. For the next 68 years [ until 1979 ] no earthquakes of magnitude 6 or larger occurred in the region between1979 and 1989. There have occurred four magnitude 6 or greater earthquakes including Loma Praeta earthquake .This clusters of earthquakes have led scientists to estimate that there is a probability of a magnitude 6.8 or larger earthquake occurring during the 30 years in the San Francisco Bay [twice as likely as not ]
As population increases, expansion of urban development and construction works has encroached upon areas susceptible to earthquakes. With a better understanding of the cause and effect of earthquakes, we may be able to reduce damages and loss of lives from the destructive phenomenan .
Among the biggest earthquakes that resulted in heavy loss of human lives and properties are :–
——Valdivia , Chile , 22 May 1960 [ 9.5 ] on the Richter scale
Killed 1655 people, 550 million usd in damages
——Sumatra , Indonesia , 26 December 2004 [ 9.1 ] on the Richter scale
Killed 227,900 people
——Sendai, Japan 11mMarch 2011 [ 9.0] on the Richter scale
Killed several thousands people
——-Ecuador Coast ,31 January 1906 [ 8.8 ]on the Richter scale
Killed between 500 and 1500 people
——Sumatra, Indonesia 28 March ,2005 [ 8.6] on the Richter scale
Killed 1313 people
Taking the preparatiory measures to respond timely to the possible earthquakes is the best policy for mitigating the impacts of loss of lives and properties. In this regard, we may take the following measures:—
Contact your local emergency management office ,local Red Cross ,State Geological Survey or Department of Natural Resources for specific information about your community’s risks.
*Bearing in mind the fact that mobile home and home not attached to the foundation are at particulaly at risk during the earthquake;
*Be aware of the fact that building with foundation resting on landfill and other unstable soil are at increased risk of damage;
*Know that doorways are not stronger than any other part of a structure; so don’t rely on them for protection. During an earthquake ,get under a strong piece of furniture and hold onto it. It will help shelter you from falling objects that could injure you during an earthquake. Tell, your community ,your school or your organization to update emergency plan and supplies in order to be able to prevent damages and injuries. The Union of Myanmar has already laid down a comprehensive plan in the form of a STANDING ORDER ON NATIONAL DIASASTER MANGEMENT. Ministries concerned, NGOs both local and foreign and CSOs are all encouraged to make concerted effort to combat the risks of this disaster and to mitigate the losses of lives and property.