As part of a long-term collaboration, a team from the Earth Observatory of Singapore (EOS) and the Indonesian National Research and Innovation Agency (Badan Riset dan Inovasi Nasional, BRIN) have installed the first station of an initiative aimed at gathering more data to improve the assessment of seismic and tsunami hazards in a region of the Mentawai Islands in Indonesia known as the Mentawai Seismic Gap. This area has curiously not experienced a major earthquake in a long time, making it a potential location for a future event. 

 

The new station is located on Siberut, the largest island of the Mentawai Islands, which is right above the Mentawai Seismic Gap. It is a Global Navigation Satellite System (GNSS) station, which uses electromagnetic signals from satellites to provide accurate estimates of its location through time. 

The GNSS station was installed in September 2024 by members of the EOS Centre for Geohazard Observations (EOS CGO) and of the Research Center for Geological Disaster at BRIN. The scientists hope that the data collected by the station will inform about the tectonic movements of the Mentawai Seismic Gap. These movements are related to the tectonic plate boundary that borders Indonesia, called the Sunda Megathrust, that has hosted several great earthquakes such as the 2004 Indian Ocean earthquake and tsunami. "Better understanding the surface deformation in the seismic gap from the dense GNSS network will help explain why the region has not had a major earthquake in such a long time compared to the surrounding regions of the Sunda Megathrust, which will inform about future seismic hazard and the potential for tsunamis,” said Dr Susilo, a Senior Researcher at the Research Center for Geological Disaster at BRIN, who was part of the team installing the new station.

The station is an addition to the existing Sumatran GPS Array (SuGAr) network, which comprises more than 40 stations mainly located along West Sumatra to provide information on the Sunda Megathrust and the Sumatran fault. “The densification of the network will enhance our ability to measure deformation patterns within Siberut and the Mentawai Seismic Gap, such as those related to movement of the tectonic plates and the regular seismic activity in the region,” said Dr Iwan Hermawan, a Research Fellow in the EOS CGO team who led the installation of the new station. 

In contrast to the existing SuGAr stations, the new station is a low-cost version that was designed to optimise resources while maintaining good data quality. “We aim to harness the innovative spirit of the CGO staff to develop and assemble low-cost field observational systems,” added Mr Leong Choong Yew, the Director of the EOS CGO. “Lowering the cost will enable us to deploy more instruments and collect even more data necessary for the understanding of tectonic behaviours of the area. The field deployment will help validate our innovative efforts.”

Located close to a school, the station also provides a unique opportunity to promote education and engagement with local communities. During the field trip, the team distributed flyers and posters to the school children that explained the station and what the instrument will be used for, an effort supported by the EOS Community Engagement Office. “Installing stations in local communities requires extensive engagement on the ground,” said Dr Juniator Tulius, a Research Fellow in the EOS CGO team who is from the Mentawai Islands, and who was responsible for the logistics of the trip and for facilitating local engagements. “We met with the village leader and the school principal to explain what the station is, how it works and what data it provides. We aimed for the installation of the station to also be an educational opportunity for the village.”  

The team plans to install seven more stations in different parts of Siberut by the end of 2024, to provide a comprehensive understanding of how each site and the region are moving. The data collected will allow to build detailed models of the Mentawai Seismic Gap, which will inform about the seismic and tsunami hazards from the region. "The addition of the new low-cost stations to the current SuGAr network, which has been operational for more than two decades, will greatly enhance the efforts of the Indonesian government to improve community resilience concerning earthquake hazards, especially in the Megathrust zone of western Sumatra. Unquestionably, this network has constantly given priceless information and strengthen disaster research in Indonesia," said Dr Deasy Arisa, a Senior Researcher at the Research Center for Geological Disaster at BRIN, who was also part of the team installing the new station.

The installation of the new GNSS stations is part of the research programme ‘Integrating Volcano and Earthquake Science and Technology’ (InVEST) in Southeast Asia. The data collected will help understand the potential for earthquakes and tsunamis from the Mentawai Seismic Gap and the surrounding region of the Sunda Megathrust. “We hope that the densification of the network will help us better monitor the current status of the Mentawai Seismic Gap, determine how much strain has accumulated, and whether any strain is being quietly released through slip without generating big earthquakes,” said Assistant Professor Lujia Feng from the Asian School of the Environment and EOS, who is also a Principal Investigator on the InVEST programme. A better understanding of the Mentawai Seismic Gap will contribute to the goals of the research programme to provide a holistic understanding of regional tectonics, volcanoes, the linkages between the two, and their cascading hazards and impacts. 

The initiative is part of the long-term goal of EOS researchers to innovate new technologies and work collaboratively with scientists from the region to better understand the geohazards the Southeast Asian region is facing.