Tsunami is one of the natural disasters that have occurred several times in various countries in the world. One of them is Indonesia. It is still clearly remembered that the tsunami that hit Aceh in 2004 ago. The disaster has claimed hundreds of thousands of lives. The lack of early detection of the tsunami caused severe damage and resulted in the deaths of many casualties. It takes a tsunami measuring device that can also detect large tsunami waves.

Indonesia has a tsunami detection system called Indonesia Tsunami Early Warning System or abbreviated InaTEWS. This system was built built by the Meteorology, Climatology and Geophysics (BMKG) together with a number of parties in year 4 after the devastating tsunami in Aceh. There are several tool components that support the work of this system. Here is the explanation. The first thing that works in a measuring instrument is the detection function. In the study of natural disasters, there are so-called early detection. Early detection is an information that informs the danger before the disaster. In the case of the tsunami disaster, an early detection system, known as the tsunami warning system, was created. This system was developed to detect some of the symptoms that have the potential to cause a tsunami disaster. One cause of the tsunami is the earthquake with a very large force where the hypocentrum occurs in the seabed.

When an earthquake occurs, seismometers installed throughout Indonesia will record and record earthquake waves. There are more than 600 seismometers installed, of which 500 are accelerometers while the rest are broadband seismometers. The entire tool is classified into ten regions. These ten regions include:

  • Regional Center 1 in Medan - North Sumatera
  • Regional Center 2 in Banten Province
  • Regional Center 3 in East Java Province
  • Regional Center 4 in South Sulawesi Province
  • Regional Center 5 in Jayapura - Papua
  • Regional Center 6 in West Sumatra Province 
  • Regional Center 7 in Daerah Istimewa Yogyakarta
  • Regional Center 8 in Kupang - Timor Island
  • Regional Center 9 in Ambon
  • Regional Center 10 in Manado - North Sulawesi

The distance between one device with another in a region of about a hundred kilometers. With that distance, an earthquake wave will be recorded within a few seconds. The recorded data is then sent to the center via the VSAT communications satellite. Then will be analyzed to the data so that known point of earthquake center. When the earthquake that meets the tsunami criteria, the tsunami disaster warning will be announced.

GPS and Tide Gauge
BMKG also installed geodetic and tide gauge GPS equipment throughout Indonesia to form a GPS and tide gauge network. Geodetic GPS functioned for earthquake mitigation purposes. While tide gauge aims to detect the tides of sea water after the earthquake.

Tide gauge is a measuring instrument used to determine changes in sea level, either mechanically or automatically. It has pressure components, radar sensors and float sensors. The ideal tide gauge is installed near the point of the plate in the middle of the calm sea. But in fact, these tools are often installed in the calm sea zone though not close to the point of the plate. This is due to the high cost of installation.

There are at least 40 GPS and 80 tide gauges planned to be installed and controlled by Bakosurtanal. The use of both tools is to observe the movement of the earth's plate. Data on the direction of the earth's plate movements is needed to predict areas prone to earthquakes in the future. The data obtained will be sent directly to BMKG center using VSAT.

Buoy is a tool that serves as a marker installed in the sea. At first the buoy was installed for ship loading and unloading activities. However, this tool is then also enabled to observe possible tsunamis in the area. Buoy has a sinker called sinker. This sinker is connected with a buoy using a chain that is twice the depth of the sea buoy installed. In general, buoys have bright colors such as yellow to be easily recognizable and not hit by a ship.

Indonesia through BPPT has installed several buoys in the Indian Ocean. Installation of this buoy is a cooperation between Indonesia and Germany. But there are buoys that are changing due to the ocean currents. Buoy is carried by the ocean currents due to the breaking of chains or sinkers that connect the ballast with the buoy. Some of the buoys in Indonesian waters are also the result of cooperation between Indonesia with WaveScan Malaysia, GITEWS Germany and DART Buoy United States.

Communication System Accelerometer, GPS, Tide Gauge and Buoy
As has been explained that each tool produces data. Then how the data can get into the hands of analysts? The entire BMKG-managed tool sends data to BMKG center through a sophisticated communication system. This system uses VSAT communications. There are three types of VSAT: LIBRA system, Provider system and Reftec system.

Before reaching the people's ears, information that is processed from the data of various tsunami detection devices has gone through several stages.

  • The first stage, data received from the accelerometer, GPS, tide gauge and buoy will be analyzed by BMKG and stored in the tsunami database.
  • The second stage, in addition to being stored in the database, the data is already in the form of information and then forwarded to the Indonesian communication network provider, to print and electronic media, and forwarded to government agencies (provincial and district government) and other agencies such as BNPB, POLRI, TNI, Kominfo.
  • The third stage, the information that has reached to some of these parties is immediately notified to the wider community, especially coastal communities. The local government (PEMDA) is also obliged to sound the siren of tsunami hazard.

Communication system has been arranged so neatly and systematically. Just how to do it. If the community has been trained to cope with the tsunami disaster and government authorities are quick to respond to the disaster, then the damage and casualties could be minimized.

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