Source reconstruction of the 1969 Majene, Sulawesi earthquake and tsunami: A preliminary study

© Copyright 2021 The Author(s). We studied the February 23rd, 1969 M7.0 Majene, Sulawesi earthquake and tsunami. It was followed by tsunami reported at five locations. At least 64 people were killed and severe damage on infrastructures were reported in Majene region. Based on damage data, we estimated that the maximum intensity of the earthquake was MMI VIII. Focal mechanisms, derived using first motion polarity analysis, indicated that the earthquake had a thrust mechanism. Furthermore, we built hypothetical earthquake scenarios based on a rectangular fault plane of 40 km × 20 km with a homogeneous slip model of 1.5 m. We run the Open Quake and the JAGURS code to validate the macroseismic and tsunami observation data, respectively. Our best-fitted earthquake model generates maximum intensity of 8+ which is in line with the reported macroseismic data. However, the maximum simulated tsunami height from all scenario earthquakes is 2.25 m which is smaller than the 4 m tsunami height observed at Pelattoang. The possibility of contribution of another mechanism to tsunami generation requires further investigation.Royal Society, UK (grant number CHL\R1\180173)

Source reconstruction of the 1969 Sulawesi, Indonesia earthquake and tsunami

This study is funded by the Royal Society (UK) grant number CHL/R1/180173.vEGU21: Gather Online Session NH5.1An M7.0 earthquake followed by moderate tsunami destructed Majene region, western Sulawesi on 23 February 1969. This event claimed at least 64 lives and caused severe damage to infrastructure. In this study, we reconstructed the earthquake and tsunami source of this event by optimising macroseismic and tsunami dataset reported as well as analysed the earthquake focal mechanism. We estimated that the maximum intensity of the earthquake was VIII (in Modified Mercalli Intensity). From the first motion polarity analysis, the earthquake had a thrust mechanism which was plausibly from the Makassar Thrust. Further, deterministic ground motion modelling successfully fits the intensity data. However, thrust earthquake from the Makassar Thrust was unable to reconstruct 4 m tsunami height observed at Pelattoang. The estimated ratio between maximum tsunami run-up height and lateral distribution distance (I2) from the dataset indicates that the tsunami was generated by a local coastal landslide.Royal Society (UK) grant number CHL/R1/180173

Tsunami risk communication and management: Contemporary gaps and challenges

Supplementary data: The following is the Supplementary data to this article: Acrobat PDF file (2MB) available at: https://ars.els-cdn.com/content/image/1-s2.0-S2212420921007329-mmc1.pdfCopyright © 2022 The Authors. Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures.COST (European Cooperation in Science and Technology); Royal Society, UK (grant number CHL\R1\180173); Severo Ochoa Centers of Excellence Program (CEX 2018-000797-S) funded by MCIN/ AEI /10.13039/501100011033; Lloyd's Tercentenary Research Foundation, the Lighthill Risk Network, and the Lloyd's Register Foundation-Data Centric Engineering Programme of the Alan Turing Institute

A low-angle normal fault earthquake and tsunami: The 1852 Banda Sea Earthquake, Eastern Indonesia

In November 1852, the Banda Islands, Eastern Indonesia suffered a devastating earthquake which was followed fifteen minutes later by a tsunami with up to eight meters height. Strong shaking was also felt on Ambon, Saparua, and Haruku Islands. The tsunami was also reported on these three islands. Almost all previous studies suggest that it was due to a giant megathrust earthquake from the Banda Arc. On the other hand, a recent tectonic study and our own research show that a smaller earthquake on the Banda detachment fault system is more likely to have produced the tsunami reported in 1852. The Banda detachment is a low-angle normal fault which has never been considered before as a source of seismic or tsunami hazard in this region. It has a shallow dip angle observed on land consistently along the outer margin of the Weber Deep. The dip gradually decreases to almost flat on the bottom of the basin then reverses sense, forming a bowl-like shape beneath the inner volcanic arc islands. However, recent seismicity shows no evidence for normal earthquakes with low-dip angle mechanism in this area. Thus, the fault could either be creeping or experience infrequent large earthquakes. We apply three techniques to localize the earthquake hypocenter and estimate the magnitude. By using a grid-search, earthquake intensity attenuation function, and tsunami backward-ray tracing methodologies, the source is constrained near the Banda Islands. The only major fault near this constrained area is the Banda detachment. Then we verify this finding by forward tsunami and seismic modelling. Lastly, we conduct seismic and tsunami hazard assessment. We assess the hazard impact for the Banda Sea due to sources from the Banda Arc and the Banda detachment system

Long tsunami oscillations following the 30 October 2020 Mw 7.0 Aegean Sea earthquake: Observations and modelling

National Science Foundation under Cooperative Support Agreement; Royal Societ

High potential for splay faulting in the Molucca Sea, Indonesia: November 2019 Mw7.2 earthquake and tsunami

the Royal Societ