New mareograph devices to monitor possible tsunamis from landslides or volcanic explosions installed in Indonesia

On December 2018 a tsunami was generated by the collapse of the Anak Krakatau Volcano, with waves propagating in all directions inside the Sunda Strait — the sea portion between the Java and Sumatra Islands — and causing 437 fatalities. Later, in April 2022, the Anak Krakatau erupted, and the ash column reached up to 3,000 km high from the summit of the volcano, with national authorities raising the Alert Level to III (Standby Phase).  

After the event of 2018, 2 IDSL (Inexpensive Device for Sea Level Monitoring) devices were installed on Sebesi Island and in Marina Jambu, the closest locations where GSM communication was available, as part of a Tsunami Early Warning System. Each is composed of a series of sensors positioned in the closest desert islands around the volcano. Once a number of stations identifies an alerting condition, appropriate measures for informing the local authorities of a potential tsunami being generated from the volcano can be issued. 
 
This year, as the volcano’s activity started increasing in February, a new installation – which can be followed in near real-time - took place at the Rakata island in April to allow the detection of the waves much earlier, just a few minutes after the initiation of the events. 
Therefore, the teams involved in the early warning system are confident the devices will be able to provide alerts — under the shape of an email/SMS that is sent to Indonesia’s Meteorology, Climatology, and Geophysical Agency — before the wave reaches populated places. Moreover, 2 units of PUMMA (the Indonesian version of IDSL) have further been installed in Panjang island, right next to Rakata, to provide additional data.
The installation of the devices was done on an already existing navigation platform, and it was particularly complex because no communication network was available there. To solve this, BMKG and BAKTI installed a dedicated satellite system that now provides the IDSL internet connection that allows sending high-frequency sea level data in real-time to the server.  
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Link: https://webcritech.jrc.ec.europa.eu/TAD_server/Device/634