Tsunamis in the Sunda Strait could be triggered by volcanic eruptions and tectonic earthquakes sourced in the megathrust zone, according to daryono, head of the earthquake and tsunami mitigation agency of the Climatology and Geophysics Meteorology Agency (BMKG).
Based on historical records, the tsunami caused by the eruption of Mount Krakatau in 1883 was able to reach Jakarta Beach because the height of the tsunami at its source was more than 30 meters, while the tsunami in 2018 was much smaller, so it did not reach Jakarta.
“To find out whether the tsunami caused by the Sunda Strait megathrust earthquake can reach Jakarta, tsunami modeling is needed. Modeling of the Sunda Strait tsunami due to the magnitude 8.7 earthquake conducted by BMKG shows that the tsunami can reach Jakarta Beach,” he said, as quoted from Instagram @daryonobmkg, Monday, August 23, 2021.
The modeling results showed that the tsunami reached Jakarta Beach within about 3 hours after the earthquake with a height of 0.5 meters in Kapuk Muara-Kamal Muara and 0.6 meters in Ancol-Tanjung Priok.
Tsunami modeling is measured from the average sea level (mean sea level). In the worst cases, if a tsunami occurs at high tide, then the height of the tsunami can increase. In addition, the height of the tsunami can also increase if the coast of Jakarta has experienced a decrease in surface (subsiden).
Tsunami modeling has very high uncertainty. This is due to the very sensitive modeling equations with the data and earthquake generating sources used.
“Different data used, then the results will be different. Even if the source of the tsunami is shifted slightly, then the results will also be different. This is why there is always a difference in results between tsunami model makers,” daryono said.
Pemodelan tsunami Selat Sunda akibat gempa M8,7 yg dilakukan BMKG menujukkan bhw tsunami dpt sampai Pantai Jakarta. Hasil pemodelan menunjukkan tsunami sampai Pantai Jakarta sekitar 3 jam setelah gempa, dgn tinggi 0,5 m di Kapuk Muara-Kamal Muara dan 0,6 m di Ancol-Tg Priok. pic.twitter.com/v9CUlhJfCZ— DARYONO BMKG (@DaryonoBMKG) August 21, 2021