Warning Receiver System (WRS) that contains the earthquake parameters, such as magnitude, location, depth, extent of damage in different areas of earthquake and tsunami warning. WRS data must be shown by broadcasters when displaying a stop press or breaking news when the earthquake.This data was obtained from a tool called accelerograph, which can be installed in the ground or rooftop. The intensity scale is usually mentioned in the Modified Mercalli Intensity (MMI). This differs from the Richter scale, which only give out information strength epicenter.
Accelerograph works by measuring changes in the speed of earthquake waves. When an earthquake occurs, the wave energy propagates in all directions at a certain speed. Differences layers and the soil structure making the speed of propagation of a change at any time so that energy transfer also change. Seismograph itself serves to measure the speed of earthquake waves.
This can be likened to the effects of perceived passenger trains. When driving normally, the train moving with constant velocity. However, when the driver suddenly pulled the brake lever, the speed of passenger trains have changed so that the thrust.
In a building, change of pace like this also raises the thrust. If the seismic wave velocity changes occur very fast and intense, the building will be shaken. "Damage to buildings caused by a change of pace," said Head of the Earthquake and Tsunami BMKG Suhardjono, on Tuesday last week.
On the pendulum there accelerograph associated with spring. When earthquakes propagate, the pendulum moves come, greater changes in seismic wave velocity, the greater the shocks caused. If the shock is very large, the structure can be destroyed. Likewise, when the change in velocity occurs in a short time, the more intense the shock will make the destruction of the structure occurs more rapidly. The information recorded this tool and then sent via satellite, then transmitted to the BMKG monitoring center of the earthquake and tsunami.
According Suhardjono, the office has installed 210 accelerograph in areas prone to earthquake in Indonesia. This amount is half way from the target 500 accelerograph in 2015. "Our goal is to create a map of an earthquake shock," he said.
This map illustrates the shock inflicted on various parts of the epicenter. This map accurately describes the intensity of the earthquake to a patch of territory as counties or cities for relief because it provides information which areas are experiencing severe shocks.
Although accelerograph growing in the coming years, that number is still not enough. In Japan, accelerograph mounted very tightly so that the country has an area of Sumatra Island 1,000 devices. This is particularly advantageous because, the closer the accelerograph, the more detail the extent of damage is measured.
In the future, BMKG will include a map shocks along with the usual magnitude of information published in every tsunami information. But these institutions still thinking, a way to facilitate the reading of shocks in order to map information; not misinterpreted by many parties. Including by the media .*** [ANTON WILLIAM | KORAN TEMPO 3593]
Mercalli Intensity Scale of an Earthquake
- 1 MMI: Vibration is not felt except in exceptional circumstances by some people.
- 2 MMI: Vibrations felt by some people, the objects are hung swaying lightly.
- 3 MMI: Tremors felt real in the house. Vibration feels as if there was a truck passing by.
- 4 MMI: During the day felt by many people in the house, out by several people, broken pottery, window / door rattling, and the wall of sound.
- 5 MMI: Vibrations felt by almost all people, the crowd woke up, broken pottery, broken windows and so on, things bounced, poles and great stuff looking swing, pendulum clock can be stopped.
- 6 MMI: Vibrations felt by all residents. Most residents were surprised and ran outside, plaster walls and fallen chimneys broken at the factory, minor damage.
- 7 MMI: Everyone out of the house. Minor damage occurred to buildings and good construction. While the construction of buildings with less well occur even destroyed cracks, chimneys broken. Felt by the people who ride the vehicle.
- 8 MMI: Slight damage to poorly constructed building, the wall can be separated from the frame house, Chimney factory and monuments collapsed, the water becomes turbid.
- 9 MMI: Damage to building a strong, house frames become misaligned, a lot of cracks. The house looks rather move from its foundation. The pipes in the house broke up.
- 10 MMI: The building of a strong wood is damaged, order a house off its foundation, the ground split, curved rails, landslides in each of the rivers and on steep lands.
- 11 MMI: only a few buildings that remain standing. The bridge is broken, there valley. Pipe in the ground can not be used at all, the ground split, curved rails once.
- 12 MMI: Crashed at all. Waves appear on the surface of the soil. The view becomes dark. Objects thrown into the air.
