Field Survey and Numerical Modelling of the December 22, 2018 Anak Krakatau Tsunami

Borrero, José C.; Solihuddin, Tubagus; Fritz, Hermann M.; Lynett, Patrick; Prasetya, Gegar; Skanavis, Vassilios; Husrin, Semeidi; Kushendratno,; Kongko, Widjo; Istiyanto, Dinar Catur; Daulat, August; Purbani, Dini; Salim, Hadiwijaya Lesmana; Hidayat, Rahman; Asvaliantina, Velly; Usman, Maria; Kodijat, Ardito; Son, Sang Young; Synolakis, Costas E.

doi:10.1007/s00024-020-02515-y

Cited by 42 publications

(27 citation statements)

References 19 publications

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“…The strong tsunami-induced currents entering and exiting the marina area through a narrow entrance between two breakwaters caused damage to floating docks and tore vessels from their moorings, leading to numerous collisions. Around New Zealand, bays and harbors prone to long wave resonance were activated by the surges, with Wellington Harbor in particular showing a longlasting resonant signal at its fundamental modes [12,13].…”

Section: Tsunami Observations and Impactsmentioning

confidence: 99%

The Tsunamis Generated by the Hunga Tonga-Hunga Ha'apai Volcano on January 15, 2022

Lynett

2022

Preprint

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On the evening of January 15th, 2022 at approximately 5:15 pm local time (4:15 am Greenwich Mean Time), the Hunga Tonga-Hunga Ha'apai volcano unleashed a violent underwater eruption, blanketing the surrounding land masses in ash and debris (1). The eruption generated tsunamis observed throughout the globe. The last time such an event occurred was the 1883 Krakatau eruption (2), and thus here we have the first observations of a tsunami from a large emergent volcanic eruption captured with modern instrumentation. The mechanisms of tsunami generation here are rare and complex, but a wealth of observations permit a forensic analysis. With the use of oceanographic and meteorological data, post-event field survey observations, and high-order hydrodynamic modeling, we show that the event generated tsunamis at different times and from distinct mechanisms. There is evidence of a relatively small wave generated through a pre-cursor source approximately 10 minutes before the primary eruption; due to lack of observational data, it is difficult to specify the source of these waves, but a submarine landslide associated with an early eruption is possible. The main eruption appears to have generated waves through multiple mechanisms, including: 1) air-sea coupling with the initial and powerful shockwave radiating out from the explosion in the immediate vicinity of the eruption, 2) the collapse of the water-crater created by the underwater explosion, and 3) air-sea coupling with the air-pressure wave that circled the earth multiple times, leading to a global tsunami. In the nearfield, the tsunami impacts are strongly controlled by the shockwave and water-crater source, while the far-field tsunami, which was uncommonly persistent, can be largely described by the air-pressure wave mechanism. Catastrophic damage in some harbors in the far-field was averted by just 10’s of cm, implying that a modest sea level rise combined with a future, similar event would lead to a step-function increase in infrastructure impacts. Piecing together the complexity of this event has broad implications to the hazard in similar geophysical

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Section: Tsunami Observations and Impactsmentioning

confidence: 99%

The Tsunamis Generated by the Hunga Tonga-Hunga Ha'apai Volcano on January 15, 2022

Lynett

2022

Preprint

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“…Tsunami source analysis conducted by Heidarzadeh et al (2020a), which was validated by actual tide gauge records of the AKT, resulted in a source model having 100-150 m initial wave height. In addition to the fact the aforesaid source model was validated by actual tide gauge records of the AKT, the other evidence for this source model comes from Borrero et al (2020) who reported a runup of 85 m on the coast of a nearby island to the AKV, i.e. Rakata Island, which is located * 5 km to the south of the AKV.…”

Section: Hydrodynamic Analysismentioning

confidence: 94%

Field Survey of Tsunami Heights and Runups Following the 22 December 2018 Anak Krakatau Volcano Tsunami, Indonesia

Heidarzadeh

Putra

Nugroho

et al. 2020

Pure Appl. Geophys.

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The 22 December 2018 Anak Karakatau tsunami in Indonesia was a rare event in that few instrumental records existed of tsunamis generated by volcanic sources before this event. The tsunami, which left a death toll of 437, is of global importance as it provides opportunities to develop knowledge on generation, propagation and coastal effects of volcanic tsunamis. Here, we report results of field surveys along the coast of the Sunda Strait, Indonesia to study tsunami wave heights and coastal damage. We surveyed 29 locations and measured ranges of tsunami runup from 0.9 to 5.2 m, tsunami heights from 1.4 to 6.3 m, flow depths from 0.2 m to 3.0 m and inundation distances from 18 to 212 m. The largest tsunami heights and concentration of damage and fatalities occurred on the western shore of Java from Tanjung Lesung to Sumur. The largest cluster of fatalities occurred at Tanjung Lesung, where more than 50 people died while attending an outdoor music being held at the shoreline. The tsunami runup and tsunami height in Tanjung Lesung were 4.0 and 2.9–3.8 m, respectively. We believe this tragedy could have been avoided if the event organizers were more aware of the hazard posed by the Anak Krakatau volcano, as it had been actively erupting for several months prior to the tsunami, and simply moved the concert stage 100 m inland. Many of the locations surveyed demonstrated a similar pattern where the majority of casualties and destruction occurred within 100 m of the coast; in several locations, lives were saved where buildings were located at least this distance inland. The significant damage and numerous deaths which occurred in Sumur, despite the moderate tsunami height of 2.3–2.5 m, can be attributed to the extremely low-lying coastal land there. Flow depth in Sumur was 0.9–2.0 m. During our field surveys, nearly one year after the event, we noted that some of the damaged buildings were being rebuilt in the same locations just 10–30 m from the shoreline. We question this practice since the new buildings could be at the same tsunami risk as those damaged in the 2018 event.

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“…They systematically documented in-field measurements of tsunami heights, runups and tsunami inundation distances along the eastern and western coasts of Palu Bay. Tsunami heights and runups were measured depending on the situation at each site, with a summary definition of each measurement shown in Borrero et al (2020). Inundation limits were estimated from swept up debris and personal belongings onshore, video and photographic evidence taken by 2 in Supplemental Material).…”

Section: Tsunami Surveymentioning

confidence: 99%

Field Insights and Analysis of the 2018 Mw 7.5 Palu, Indonesia Earthquake, Tsunami and Landslides

Cilia

Mooney

Nugroho³

2021

Pure Appl. Geophys.

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A devastating Mw 7.5 earthquake and tsunami struck northwestern Sulawesi, Indonesia on 28 September 2018, causing over 4000 fatalities and severe damage to several areas in and around Palu City. Severe earthquake-induced soil liquefaction and landslides claimed hundreds of lives in three villages within Palu. The mainshock occurred at 18:03 local time at a depth of 10 km on a left-lateral strike-slip fault. The hypocenter was located 70 km north of Palu City and the rupture propagated south, under Palu Bay, passing on land on the west side of Palu City. The surface rupture of the earthquake has been mapped onshore along a 30 km stretch of the Palu-Koro fault. We present results of field surveys on the effects of the earthquake, tsunami and liquefaction conducted between 1–3 and 12–19 of October 2018. Seismic intensities on the Modified Mercalli Intensity (MMI) scale are reported for 375 sites and reach a maximum value of 10. We consolidate published tsunami runup heights from several field studies and discuss three possible interrelated tsunami sources to explain the variation in observed tsunami runup heights. Due to limited instrumentation, PGA and PGV values were recorded at only one of our field sites. To compensate, we use our seismic intensities and Ground Motion to Intensity Conversion Equations (GMICEs) and Ground Motion Prediction Equations (GMPEs) developed for similar tectonic regions. Our results indicate that the maximum predicted PGAs for Palu range from 1.1 g for GMICEs to 0.6 g for GMPEs.

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Field Survey and Numerical Modelling of the December 22, 2018 Anak Krakatau Tsunami

Cited by 42 publications

References 19 publications

The Tsunamis Generated by the Hunga Tonga-Hunga Ha'apai Volcano on January 15, 2022

The Tsunamis Generated by the Hunga Tonga-Hunga Ha'apai Volcano on January 15, 2022

Field Survey of Tsunami Heights and Runups Following the 22 December 2018 Anak Krakatau Volcano Tsunami, Indonesia

Field Insights and Analysis of the 2018 Mw 7.5 Palu, Indonesia Earthquake, Tsunami and Landslides

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