Since December 2004, until now Indonesia has suffered many catastrophes like Aceh tsunami and earthquake, Nias earthquake, Jogjakarta earthquake, Tasikmalaya earthquake, and most recent West and South Sumatra earthquakes. What caused these earthquakes ? According to our geologists, the position of Indonesia between two major plates, Asian plate and Australian plate, will caused many possibilities of earthquake. Like the recent West Sumatra earthquake, was caused by the movement of two plates in the area of West Sumatra. Due to the meeting of Indian Ocean tectonic plates under Asian plate in Sumatra West Coast.

These earthquakes are getting bigger, last earthquake I've been experienced before the Tasikmalaya earthquake was about 10 years ago in Jogjakarta, but the intensity was not as big as today. Larger earthquakes have been found these days and I'm afraid they will increase the possibility of subsequent quakes across the globe. Just imagine, if one plate moves in certain area, don't you think it will cause another movement in another area ? Because since Italy earthquake early this year, I wondering which area will get the reflection, and now I found out : my country.

Beneath the ocean between Sumatra and Java islands there is one big and dangerous volcanic mountain : Krakatau mountain. I could not imagine what will happen with this mountain after the earthquake. Like one of my fellow hubber Prasetio30 once said, he just prays and prays.
Scientists reported that the activity of Krakatau mountain has increased significantly during these days.

I feel the urgency of early warning system in my country. Even if the system may give a false signal, I still prefer that. How actually scientist predict the earthquake ?

Scientists study the past frequency of large earthquakes in order to determine the future likelihood of similar large shocks. For example, if a region has experienced four magnitude 7 or larger earthquakes during 200 years of recorded history, and if these shocks occurred randomly in time, then scientists would assign a 50 percent probability (that is, just as likely to happen as not to happen) to the occurrence of another magnitude 7 or larger quake in the region during the next 50 years.

According to wikipedia, an earthquake prediction is a prediction that an earthquake of a specific magnitude will occur in a particular place at a particular time (or ranges thereof). Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific hour, day, or month but for well-understood faults, seismic hazard assessment maps can estimate the probability that an earthquake of a given size will affect a given location over a certain number of years.

Well, there is one man in my county named Mbah Maridjan or Maridjan Grandad. He doesn't have educational background but he works as Merapi volcanic mountain guardian. Don't get me wrong, he is not get paid for that. It was his spiritual decision. He seems understand the mountain, he could tell people whether the mountain will erupt today or not. I never known this man until a few years ago when Merapi volcanic mountain will erupt and all the scientists in meteorology and geophysics board had warned the villagers to be evacuated. This man refused to be evacuated, he had known for sure that the mountain would not erupted that day. Although finally he agree to be evacuated, he did it just to obey the Sultan's (Jogjakarta King) order. And you know what, the Merapi mountain did not erupt that day. Surprising ability. But such case is rare and I believe in scientist report more than spiritual advise like that. You have to consider both warning I think, science and spiritual.

In the effort to predict earthquakes, people have tried to associate an impending earthquake with such varied phenomena as seismicity patterns, electromagnetic fields, ground movement, weather conditions and unusual clouds, radon or hydrogen gas content of soil or ground water, water level in wells, animal behavior, and the phases of the moon. In fact, before the Tasikmalaya earhquake has happened, I saw many cockroachs about half a dozen I think, appeared from nowhere. I never thought that it could be a sign of earthquake. But insects have strong instinc, they could predict underground movement like underwater movement, I think. What do you think ?

One well-known successful earthquake prediction was for the Haicheng, China earthquake of 1975, when an evacuation warning was issued the day before a M 7.3 earthquake. In the preceding months changes in land elevation and in ground water levels, widespread reports of peculiar animal behavior, and many foreshocks had led to a lower-level warning. An increase in foreshock activity triggered the evacuation warning. Unfortunately, most earthquakes do not have such obvious precursors. In spite of their success in 1975, there was no warning of the 1976 Tangshan earthquake, magnitude 7.6, which caused an estimated 250,000 fatalities.

Actually, nobody can predict the earthquake, nobody will accurately knows what time, when, what area the earthquake will happen. Like the US Department of Energy once said : Scientists cannot predict earthquakes. 

But we can at least make some early warning systems that may predict the next impact of one earthquake, perhaps Like after Sumatra earthquake, which area will be next.

Some early warning systems have really worked in a country like Japan. The Japanese government provides their residents with such systems. The Japan Meteorological Agency (JMA) provides residents in Japan with Earthquake Early Warnings. This is a new system that issues prompt alerts just as an earthquake starts, providing valuable seconds for people to protect themselves before strong tremors arrive.
 
On 1 October 2007, JMA launched the Earthquake Early Warning service for provision through a number of media outlets such as TV and radio. (www.jma.go.jp)

I hope there will be a kind of early warning system in my country, The one which could possibly reach by the Indonesian people. especially in areas that have big possibility of earthquakes. Like in West coast Sumatra, Southern Coast Java, Nusa Tenggara and Papua.
It may save many people. My prayer to all the earthquakes victims and may God Bless Indonesia.