History and Goal

Tectonic Earthquake Monitoring in Indonesia

Introduction
Indonesia  is one of the most earthquakes-prone countries of the world. Because of Indonesia is at the convergence of three active tectonic plates which are generating the earthquake. A study of historical earthquakes recorded throughout the world shows that most of the epicenters of major earthquake events are concentrated in this mobile area. Some of the destructive earthquake in Indonesia that occurred in this area, including the Aceh earthquake(2004), Nias earthquake (2005), Pangandaran earthquake (2006) and Mentawai Earthquake (2010). Not a bit of loss of life and property caused by the earthquake. Therefore, monitoring of seismic activity in Indonesia is an important part in order to reduce the risk of earthquakes.

After the Aceh tsunami earthquake December 2004, Indonesia strengthening earthquake monitoring network to support the establishment of the tsunami early warning system in Indonesia. Reinforcement in the form of increasing the number and type of sensors used in monitoring earthquakes. Currently 162 broadband seismometers and 237 accelerometer has installed spread all over Indonesia to monitor seismic activity in the region. With this development, Indonesia is able to inform the parameters of earthquakes in less than 5 minutes after the earthquake.

Tectonic Setting and Seismicity of Indonesia
Indonesia lies on the boundaries of three tectonic plates, which slide past each other. These three tectonic plates are: The continental-oceanic Indo-Australian Plate to the south, the oceanic Pacific Plate to the east, the Eurasian Plate to the north(where most of Indonesia area lies), and the Philippine Plate. The Indo-Australian Plate moves north, colliding the Eurasian Plate. The Pacific Plate moves west, whereas the Eurasian Plate in relation to the other plate is not moving.

The relative movement between these four tectonic plates causes an accumulation  of pressure and mechanical stress where they collide. When the material’s elasticity is no longer able to withstand this stress, the rock will break and spring back to something close to its original shape. This rebound, which generates strong seismic waves that radiate in all directions along the tectonic plate, is called a tectonic earthquake.

Millions of these earthquakes have occurred over thousands and millions of years on the geological time scale. Evidence of these past earthquakes is recorded in natural geological phenomena (paleo-seismology). Today earthquake can be recorded using seismometer networks, which calculate an earthquake location and focal depth (hypocenter) and measure its magnitude. Approximately 4000 earthquakes happened in Indonesia per year, whereas earthquake of magnitude greater than 5.5, or earthquake that can be physically felt on land, average around 70 – 100 per years, and destructive earthquakes around one to two times a year. Between 1991 – 2011, 186 significant earthquakes were recorded in Indonesia seismic network.

Indonesian Seismic Network

Post the Aceh earthquake December 26, 2004, the government of Indonesia, decided to develop a network of digital seismic for the monitoring of regional seismic station for monitoring of regional seismicity and to collect data for tsunami early warning system. In order to monitor seismic activity in Indonesia and surrounding areas, Indonesia has developed an earthquake monitoring network consisting of Broadband Seismometers and Accelerometers spread in the region of Indonesia.  By using these new seismic networks and new seismic data analysis, Seiscomp3, Indonesia has been able to provide earthquake information to the interface institution and public less than 5 minutes after the earthquake occurred.

Figure-1: Indonesian seismic network consist of national center and 10 regional centers.

Indonesia is currently operating and maintaining 162 broadband seismometers and 237 accelerometers. Some of the accelerometer placed collocated with broadband seismometers location. Using telemetry equipment and VSat lines, these digital recordings are transmitted on  real-time mode to the central processing system at BMKG. The data are processed and issued as earthquake bulletin or tsunami warning by the central office.

Institution that monitor the tectonic earthquakes in Indonesia
Monitoring of tectonic earthquakes and tsunami activities in Indonesia are doing by Agency for Meteorology, Climatology, and Geophysics (BMKG) which is conducted in deputy of geophysics.
Accordance with Director General of BMKG’s regulation Number: KEP 03 in 2009, about the organization and work procedure of BMKG that the deputy of geophysics is executive element of some tasks and functions of BMKG in geophysics section who is responsible to Director General of BMKG.

Deputy of geophysics has tasks on formulating, executing, and controlling the implementation of technical policies, and implementing on data and information service in geophysics section. The organizational structure in deputy of geophysics is as follows :

Deputy of geophysics consists of :

  • Center of Earthquake and Tsunami
  • Center of Seismology Engineering, Geophysical Potential and Time Signal

A. Center of Earthquake and Tsunami
Center of earthquake and tsunami has tasks on implementing the technical policies formulation, provisioning of technical assistance, technical guidance, and controlling of technical policies, coordination of functional activities and cooperation, management, and services of data and information, as well as early warning in earthquake and tsunami division.

Earthquake and Tsunami Center consists of 3 divisions, there are:

  1. Division of Earthquake and Tsunami Early Information.
  2. Division of Earthquake and Tsunami Mitigation.
  3. Division of Earthquake and Tsunami Operation Development.

1. Division of Earthquake and Tsunami Early Information has tasks on implementing the disseminating of earthquake information and tsunami early warning. In performing its duties, early information division conduct the function of the implementation on monitoring, processing and data analyzing as well as dissemination of earthquake information; and implementation on monitoring, processing and data analyzing as well as dissemination of tsunami early warning.

Division of Earthquake and Tsunami Early Information consists of :

a. Earthquake Information Sub-Division; and
b. Tsunami Early Warning Sub-Division

Earthquake Information Sub-Division has tasks on data monitoring, processing, and analysing as well as dissemination of earthquake information.

Tsunami Early Warning Sub-Division has tasks on data monitoring, processing, and analysing as well as dissemination of tsunami early warning.

2. Division of Earthquake and Tsunami Mitigation has tasks on implementing the services of data and information in division of earthquake and tsunami mitigation. In performing its duties, Division of Earthquake and Tsunami Mitigation conduct the function of the implementation on services of data and information for earthquake disaster mitigation and services of data and information for tsunami disaster mitigation.

Division of Earthquake and Tsunami Mitigation consists of :

a. Earthquake Mitigation Sub-Division; and
b. Tsunami Mitigation Sub-Division

Earthquake Mitigation Sub-Division has duty to perform services in earthquake disaster mitigation.

Tsunami Mitigation Subdivision has duty to perform services in tsunami disaster mitigation.

3. Division of Earthquake and Tsunami Operation Development has tasks of preparing materials for formulation of technical policies, provisioning of technical assistance, preparation of development’s materials as well as controlling of technical policies, coordination of functional activities and cooperation in earthquake and tsunami operation development division.

In performing its duties, Division of Earthquake and Tsunami Operation Development conduct the function of preparing materials for formulation of technical policies in earthquake and tsunami operation development division, provisioning of technical assistance, preparation of development’s materials as well as controlling of technical policies in earthquake and tsunami operation development division, and implementation for coordination of functional activities and cooperation in earthquake and tsunami operation development division.

 

Division of Earthquake and Tsunami Operation Development consists of :

a. Earthquake Operation Development Sub-Division; and
b. Tsunami Operation Development Sub-Division

Earthquake Operation Development Sub-Division has tasks on preparing materials for technical policies formulation, provisioning technical assistance, preparation of development’s materials as well as controlling of technical policies, coordination of functional activities and cooperation in earthquake operation development sub-division

Tsunami Operation Development Sub-Division has tasks on preparing materials for technical policies formulation, provisioning technical assistance, preparation of development’s materials as well as controlling of technical policies, coordination of functional activities and cooperation in tsunami operation development sub-division

B. Center of Engineering Seismology, Potential Geophysics and Time Signal

Center of Engineering Seismology, Potential Geophysics and Time Signal has tasks on implementing the technical policies formulation, provisioning of technical assistance, technical guidance, and controlling of technical policies, coordination of functional activities and cooperation, management, and services of data and information in division of engineering seismology, potential geophysics and time signal.
Center of Engineering Seismology, Potential Geophysics and Time Signal consists of :

1. Division of Engineering Seismology
2. Division of Potential Geophysics and Time Signal
3. Division of Operation Development for Engineering Seismology, Potential Geophysics, and Time Signal.

1. Division of Engineering Seismology has tasks on implementing the services of data and information in division of engineering seismology. In performing its duties, Division of Engineering Seismology conduct the function of the implementation on monitoring, collecting, processing, and analyzing data in seismology engineering division, preparing materials for information services in engineering seismology division, and performing information services in engineering seismology division.

Division of Engineering Seismology consists of :

a. Engineering Seismology Data Sub-Division; and
b. Engineering Seismology Information Sub-Division

Engineering Seismology Data Sub-Division has tasks on monitoring preparation, collecting, processing and analyzing in division of engineering seismology data.

Engineering Seismology Information Sub-Division has tasks on preparing materials for services in division of engineering seismology information.

2. Division of Potential Geophysics and Time Signal has tasks on implementing the services of data and information in division of earth’s magnetic, air electrical, gravity, and time signal. In performing its duties, Division of Potential Geophysics and Time Signal conduct the function of the implementation on data and information services in division of earth’s magnetic, air electrical, and performing data and information services in division of gravity and time signal.

Division of Potential Geophysics consists of :

a. Earth’s Magnetic and Air Electrical Sub-Division; and
b. Gravity and Time Signal Sub-Division

Earth’s Magnetic and Air Electrical Sub-Division has tasks on implementing the services of data and information in division of earth’s magnetic and air electrical.

Gravity and Time Signal Sub Division has tasks on implementing the services of data and information in division of gravity and time signal.

3. Division of Operation Development for Engineering Seismology, Potential Geophysics, and Time Signal has tasks of preparing materials for formulation of technical policies, provisioning of technical assistance, preparation of development’s materials as well as controlling of technical policies, coordination of functional activities and cooperation in division of operation development for engineering seismology, potential geophysics, and time signal.

In performing its duties, Division of Operation Development for Engineering Seismology, Potential Geophysics, and Time Signal conduct the function of preparing materials for formulation of technical policies, provisioning of technical assistance and development, controlling of technical policies, and implementation for coordination of functional activities and cooperation in division of operation development of engineering seismology, and  preparing materials for formulation of technical policies, provisioning of technical assistance and development, controlling of technical policies, and implementation for coordination of functional activities and cooperation in division of operation development of potential geophysics and time signal.
Division of Operation Development for Engineering Seismology, Potential Geophysics, and Time Signal consists of :

a. Operation Development for Engineering Seismology Sub-Division; and
b. Operation Development for Potential Geophysics and Time Signal Sub-Division.

Operation Development for Engineering Seismology Sub-Division has tasks on preparing materials for technical policies formulation, provisioning technical assistance and development, controlling of technical policies, implementation for coordination of functional activities and cooperation in division of operation development for engineering seismology.

Operation Development for Potential Geophysics and Time Signal Sub-Division has tasks on preparing materials for technical policies formulation, provisioning technical assistance and development, controlling of technical policies, implementation for coordination of functional activities and cooperation in division of operation development for potential geophysics and time signal.