Performance Evaluation of IDSL for Tsunami Early Warning Systems at Bungus Port

Abstract

Indonesia is highly vulnerable to near-field tsunamis due to its tectonic setting along active subduction zones. Rapid detection of sea-level anomalies is therefore critical for the effectiveness of Tsunami Early Warning Systems (TEWS). This study evaluates the performance of an Inexpensive Device for Sea Level (IDSL) installed at Bungus Port, West Sumatra, with particular emphasis on its suitability for real-time tsunami monitoring. The performance assessment includes sea-level measurement accuracy, data gaps, transmission latency, alert functionality, and webcam-based verification. IDSL observations show strong agreement with predicted tidal data from the Geospatial Information Agency (BIG), with a correlation coefficient of 0.98 and a root mean square error (RMSE) of 0.10 m. The average data transmission latency ranges between 3 and 10 seconds, indicating near-real-time capability suitable for early warning applications. Data gaps were generally short (3–5 minutes) and were primarily caused by communication disturbances. Webcam imagery also provided reliable visual validation, with more than 90% of the images classified as good quality. Overall, the results demonstrate that the IDSL system provides reliable, low-latency sea-level monitoring and represents a promising complementary instrument for strengthening Indonesia’s TEWS, particularly in tsunami-prone coastal regions.