Real-time seismic and sea level observations are key elements in effective end-to-end tsunami warning systems. Seismic observations are used for assessing the likelihood of a tsunami being generated as well as determining the fault rupture geometry, which can be used for tsunami propagation modelling. Sea level observations are used for confirming that a tsunami has been generated. Measurements of tsunami wave heights in the open ocean, as determined by tsunameters, can be used to calibrate tsunami propagation models and to forecast estimated tsunami wave heights at the coast. Measurements from coastal sea level gauges are used for impact assessments and for informing decisions on issuing ‘all-clear’ notifications.
The number of seismic and sea level monitoring stations in the Indian Ocean has grown substantially during the last decade. Today there are over 150 broadband seismometers and over 100 sea level stations with data that are available in near real-time to Member States of the Indian Ocean Tsunami Warning and Mitigation System (IOTWMS).
The figures below show the broadband seismometers (Fig. 1) and sea level stations (Fig. 2) in operation as of December 2017. The IOTWMS seismic and sea level network databases are provided in excel and kml format via links in the right-hand column. The Indian Ocean broadband seismometers and sea level stations in operation in 2004 are shown in Figs. 3 and 4 respectively.
Fig. 1 - IOTWMS Broadband Seismometers (December, 2017)
Fig. 2 - IOTWMS Sea Level Stations (December, 2017)
Fig. 3 - Indian Ocean Broadband Seismometers (2004)
Fig. 4 - Indian Ocean Sea Level Stations (2004)