Run-up, inundation, and sediment characteristics of the 22 December 2018 Sunda Strait tsunami, Indonesia

Abstract

Abstract. A tsunami caused by a flank collapse of the southwest part of the Anak Krakatau volcano occurred on 22 December 2018. The tsunami affected the coastal areas located at the edge of the Sunda Strait, Indonesia. To gain an understanding of the tsunami event, field surveys were conducted a month after the incident. The surveys included measurements of run-up height, inundation distance, tsunami direction, and sediment characteristics at 20 selected sites. The survey results revealed that the run-up height reached 9.2 m in Tanjungjaya and an inundation distance of 286.8 m was found at Cagar Alam, part of Ujung Kulon National Park. The tsunami propagated radially from Anak Krakatau and reached the coastal zone with a direction between 25 and 350∘ from the north. Sediment samples were collected at 27 points in tsunami deposits with a sediment thickness of 1.5–12.7 cm. The average distance from the coast of the area with significant sediment deposits and the deposit limit are 45 % and 73 % of the inundation distance, respectively. Sand sheets were sporadic, highly variable, and highly influenced by topography. Grain sizes in the deposit area were finer than those at their sources. The sizes ranged from fine sand to boulders, with medium sand and coarse sand being dominant. All sediment samples had a well-sorted distribution. An assessment of the boulder movements indicates that the tsunami run-up had minimum velocities of 4.0–4.5 m s−1.

Landslide triggered tsunami modelling: A study in Anak Krakatoa collapse

“…On the contrary, Tanjung Lesung peninsula had experienced such severe damage [6] with the highest run-up height measured in the research area. Based on field observation by Muhari [6], the run-up height in the peninsula is between 7 -13.5 m with an average height of 10.6 m, while the highest run-up measured by Widiyanto [12] at the west coast of Tanjung Lesung gives 9.2 m. These field data agree with our simulation result whose water height is as high as 10 m in Tanjung Lesung but only 2 m at Lada Bay. The observation data of run-up heights around Marina and Carita are between 3-5 m, which is also very similar to our results.…”

“…As shown in Fig. 3, the run-up measurement from Widiyanto [12] recorded a low run-up height and scarce tsunami trace in this bay, meaning that the area is less affected by the 2018 tsunami. On the contrary, Tanjung Lesung peninsula had experienced such severe damage [6] with the highest run-up height measured in the research area.…”

“…Previous studies [5,6,12,13] had provided field measurement data of inundation and run-up heights caused by the 2018 tsunami in Sunda Straits. In this study, we used two measurement data [6,12] which we reckon would complement each other.…”

“…Previous studies [5,6,12,13] had provided field measurement data of inundation and run-up heights caused by the 2018 tsunami in Sunda Straits. In this study, we used two measurement data [6,12] which we reckon would complement each other. The field measurement is mainly conducted in the Tanjung Lesung peninsula and around Marina Jambu where tsunami traces were identified.…”

Mekanika Perambatan Gelombang Tsunami: Studi Kasus Tsunami Teluk Palu Dan Selat Sunda Tahun 2018

“…Tsunami Selat Sunda tanggal 22 Desember 2018 yang menyapu wilayah barat Propinsi Banten dan wilayah selatan Propinsi Lampung dipicu secara langsung oleh keruntuhan sebagian bodi Anak Rakata pada sisi barat Mekanika Perambatan Gelombang Tsunami: Studi Kasus Tsunami Teluk Palu dan Tsunami Selat Sunda Tahun 2018 (Grilli et al, 2019;Widiyanto et al, 2020). Peristiwa ini adalah salah satu contoh tsunami vulkanik yang bukan dipicu langsung oleh erupsi dari hasil pengamatan survei lapangan (Heidarzadeh et al, 2020b;Muhari et al, 2019).…”