Post-event Field Survey of 28 September 2018 Sulawesi Earthquake and Tsunami (original) (raw)
Related papers
Geophysical Journal International, 2009
The Mw= 8.4 earthquake on 2007 September 12, offshore of the Bengkulu province of Sumatra, Indonesia, generated a moderate tsunami with run-up heights of up to 4 m as measured by Indonesian and international researchers in the days following the earthquake. The tsunami was observed along 250 km of coastline and caused damage at several locations. The largest wave heights and most severe inundation were observed about 50 km to the northwest of Bengkulu; elsewhere the effects were less severe—with the exception of substantial inundation at a site 150 km to the south. In addition to presenting the field data, we conduct a modelling study and compare the run-up heights and water-level predictions from four different seismic deformation models used to initialize a tsunami propagation and inundation model. Our comparative results suggest that, for this event, the estimates of fault parameters available immediately after determination of the earthquake size and location predicted the near-field run-up heights and distribution and far-field wave equally well as estimates obtained using more detailed descriptions of the seafloor deformation, as typically available hours or days after an event. We conclude that while detailed slip patterns can be important to the near-field run-up distribution, simple fault models can be used to rapidly assess the likely near- and far-field tsunami effects of a particular earthquake.
Pure and Applied Geophysics, 2019
On September 28, 2018, a large earthquake and its accompanying tsunami waves caused severe damage to the coastal area of Palu Bay, in the central western part of Sulawesi Island, Indonesia. To clarify the distribution of tsunami inundation and run-up heights, and damage to coastal communities due to the tsunami, the authors conducted a field survey 1 month after the event. In the inner part of Palu Bay tsunami inundation and run-up heights of more than 4 m were measured at many locations, and severe damage by the tsunami to coastal low-lying settlements was observed. In the areas to the north of the bay and around its entrance the tsunami inundation and run-up heights were lower than in the inner part of the bay. The tsunami inundation distance depended on the topographical features of coastal areas. The southern shore of the bay experienced a longer inundation distance than other shores, though generally severe damage to houses was limited to within around 200 m from the shoreline. The main lessons that can be learnt from the present event are also discussed.
Coastal Subsidence Induced Several Tsunamis During the 2018 Sulawesi Earthquake
Journal of Disaster Research
The height of the tsunami caused by the Sulawesi earthquake in 2018 was higher than that estimated from the magnitude of the earthquake, and its cause is not well understood. Although it is conceivable that tsunamis originated from landslides in several cases, it is not known whether landslides were occurring in the coastal area at the time. This report describes the results of a field survey conducted to investigate the traces of subsidence and the characteristics of the tsunami incidents in the bay far from the epicenter. Subsidence was observed at a minimum of seven points along the coast; in accord with the reports of eyewitnesses, this suggests that subsidence might have generated tsunamis.
International Journal of Disaster Risk Reduction, 2019
, a series of field surveys were performed to further understand the impacts of the resulting tsunami. Tsunamis initiated by strike-slip earthquakes are rare. Other factors are suspected to have contributed to this unusual tsunami. One of these factors was the subaerial landslides around Palu Bay, which were observed at several locations. This paper aims to investigate the characteristics of the tsunami based on the flow depths/heights, tsunami inundation, wave direction and tsunami debris. The surveys were performed from 12 October to 10 November in 2018. The flow depths were measured at 84 locations along the bay. Higher tsunami depths were found at Talise Beach, which is on the closed end of the bay. The southwestern edge of Palu Bay had lower tsunami depths compared to the northeastern edge. The highest flow depth measured in this study was at the village of Tondo, at the northeastern edge of the bay. The sporadic subaerial landslides that generated the tsunami were implicated by the direction of the tsunami waves, which were inconsistent with nearby data. The combination of the complicated tsunami characteristics and the minimum level of tsunami mitigation contributed to the large number of casualties during the 2018 Palu Bay tsunami.
Pure and Applied Geophysics, 2009
This paper presents the results from an extensive field data collection effort following the December 26, 2004 earthquake and tsunami in Banda Aceh, Sumatra. The data were collected under the auspices of TSUNARISQUE, a joint French-Indonesian program dedicated to tsunami research and hazard mitigation, which has been active since before the 2004 event. In total, data from three months of field investigations are presented, which detail important aspects of the tsunami inundation dynamics in Banda Aceh. These include measurements of runup, tsunami wave heights, flow depths, flow directions, event chronology and building damage patterns. The result is a series of detailed inundation maps of the northern and western coasts of Sumatra including Banda Aceh and Lhok Nga. Among the more important findings, we obtained consistent accounts that approximately ten separate waves affected the region after the earthquake; this indicates a high-frequency component of the tsunami wave energy in the extreme near-field. The largest tsunami wave heights were on the order of 35 m with a maximum runup height of 51 m. This value is the highest runup value measured in human history for a seismically generated tsunami. In addition, our field investigations show a significant discontinuity in the tsunami wave heights and flow depths along a line approximately 3 km inland, which the authors interpret to be the location of the collapse of the main tsunami bore caused by sudden energy dissipation. The propagating bore looked like a breaking wave from the landward side although it has distinct characteristics. Patterns of building damage are related to the location of the propagating bore with overall less damage to buildings beyond the line where the bore collapsed. This data set was built to be of use to the tsunami community for the purposes of calibrating and improving existing tsunami inundation models, especially in the analysis of extreme near-field events.
Pure and Applied Geophysics, 2019
The 2018 Sulawesi earthquake (Mw 7.5) and tsunami destroyed many buildings and caused more than 3300 fatalities in Sulawesi, Indonesia. Damage reports and satellite images from Palu City indicated severe tsunami impacts to buildings and lifelines infrastructure within 300 m from the coastline. Seven-weeks after the earthquake a field survey was carried out in Palu City to measure tsunami flow depths and record damage levels for buildings, roads and electricity infrastructure. Above ground level tsunami flow depths measured at 371 building sites ranged from 0.1 to 3.65 m, with a 1.05 m mean and 0.55 m standard deviation. The survey team also recorded attributes and damage levels for 463 buildings, 7.9 km of road and 455 utility poles. We observed that non-engineered 'light timber' and 'lightly reinforced concrete' construction frame buildings were highly susceptible to 'non-structural' component damage when tsunami flow depths respectively exceed 0.4 m and 1 m above the first finished floor level, while unrepairable or complete building damage was regularly observed when flow depths exceeded 1.2 m. Only nonstructural component damage was observed for engineered 'reinforced concrete' buildings. While tsunami flow depth traces could not be measured for affected road and utility pole components, hazard intensity parameters can be obtained from tsunami inundation maps to estimate the conditions contributing to observed damage levels. The information presented herein forms an important evidence base to support future tsunami hazard and risk research in Indonesia.
Tsunamis: case studies and recent developments
2005
We present a discussion of the field surveys conducted in the wake of fifteen locally devastating tsunamis in the period 1992-2002. The goal of these surveys has been to gather homogeneous databases of run-up and inundation, for the purpose of documenting precisely the penetration of the wav es along the affected beaches. In turn, these can be used as datasets to be matched by numerical simulations of the generation of the tsunamis, their propagation and interaction with the beaches. These surveys hav e provided new insight into some complex phenomena, such as the existence of a leading depression in an N wave, the importance of beach topography on the local enhancement of run-up, the contribution of underwater landslides to tsunami hazard, and the value of an educated population in terms of the mitigation of human losses. We review a simple and robust algorithm allowing the discrimination between tsunamis generated by dislocations and landslides, based on the aspect ratio of the distribution of run-up on a nearby beach, and the comparison of maximum run-up to the seismic slip involved in the parent earthquake. Some of the techniques developed in these recent post-tsunami surveys can be extended to events dating back a few decades through the interview of elderly witnesses and the surveying of remanent watermarks. When applied to the case of the 1946 Aleutian tsunami, the resulting data require both a large dislocative source to explain the far-field tsunami, and a coeval underwater landslide to account for the near-field run-up values which reached 42 meters at the site of the Scotch Cap lighthouse.
Pure and Applied Geophysics
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 tsunam...
The September 28th, 2018, Tsunami In Palu-Sulawesi, Indonesia: A Post-Event Field Survey
Pure and Applied Geophysics, 2019
On September 28th, 2018, a powerful earthquake (M w 7.5) struck the Island of Sulawesi in Indonesia. The earthquake was followed by a destructive and deadly tsunami that hit the Bay of Palu. A UNESCO international tsunami survey team responded to the disaster and surveyed 125 km of coastline along the Palu Bay up to the earthquake epicentre region. The team performed 78 tsunami runup and inundation height measurements throughout the surveyed coastline. Measured values reached 9.1 m for the runup height and 8.7 m for the inundation height, both at Benteng village. The survey team also identified ten large coastal sectors that collapsed into the sea of Palu Bay after the earthquake. The distribution of the measured tsunami data within Palu Bay exhibits a clear localised impact suggesting the contribution of secondary non-seismic local sources to the generation of the tsunami. Findings of the field reconnaissance are discussed to provide an insight into the remaining debated source of the Palu tsunami.