Weak Near‐Field Behavior of a Tsunami Earthquake: Toward Real‐Time Identification for Local Warning

Sahakian, V. J.; Melgar, Diego; Muzli, Muzli

doi:10.1029/2019gl083989

Cited by 17 publications

(18 citation statements)

References 37 publications

(61 reference statements)

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“…Because they do not generate large-amplitude seismic waves, most of them are not felt by the population and do not produce structural damage. This was demonstrated recently using near-field displacement and strong motion data by Sahakian et al (2019). They studied 16 earthquakes of similar moment magnitude, finding that tsunami earthquakes shown less seismic radiated energy than regular earthquakes, then the amount of displacement would be estimative of seismic moment and acceleration of the radiated seismic energy.…”

Section: Introductionmentioning

confidence: 84%

Near‐Field Effects of Earthquake Rupture Velocity Into Tsunami Runup Heights

et al. 2020

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Tsunamis have often been treated as an isolated phenomena from the earthquake itself. In tsunami modeling, seafloor deformation is generated from an earthquake. That deformation is copied into the sea surface, and then, the tsunami is propagated over the ocean. On the other hand, rupture velocities from earthquakes are in the span of 1.5-2.5 km/s; therefore, it is safe to approximate the earthquake rupture propagation as an instantaneous phenomena relative to the tsunami propagation. However, this is not necessarily true for all earthquakes. Several types of large slow earthquakes or nonregular earthquakes, such as low frequency earthquakes and very low frequency earthquakes, and tsunami earthquakes have been detected and observed in certain zones around the world. A key question is: Do giant thrust tsunamigenic earthquakes produce slow rupture (0.1-0.5 km/s) velocities? In this study, we model heterogeneous earthquakes sources using very slow rupture velocities (0.1-2.5 km/s) with the aim of understanding how this parameter affects the tsunami propagation and runup. We compute the amplification due to a very slow moment release in megathrust earthquakes. Our research shows that rupture velocity plays a key role on runup amplification, and the classic instantaneous case might not work as expected for every case.

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Section: Introductionmentioning

confidence: 84%

Near‐Field Effects of Earthquake Rupture Velocity Into Tsunami Runup Heights

et al. 2020

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“…The development of new tsunami monitoring technologies will bring new opportunities for tsunami warning [151,382], reinforcing the source monitoring that is foreseen to be subject as well to dramatic progress, including specific progress related to specific atypical sources such as for example tsunami earthquakes (e.g. [284,383]). The Stromboli warning system shows that source and tsunami monitoring should coexist, as indeed is also the case for the existing warning systems for tsunamigenic landslides in Norway.…”

Section: Discussionmentioning

confidence: 99%

“…For example, Selva et al [68] adopt the results of NEAMTHM18, which extend to all the source area the method developed in [31], in which the probability distribution describing the uncertainty on the source mechanisms in each source area is set based on local geological (e.g., mapped faults), historical and instrumental (e.g., earthquake focal mechanisms) information. New rapid source inversion techniques are rapidly progressing [268,[279][280][281][282][283][284][285] and will probably reduce this uncertainty in the future. In any case, in the Mediterranean region, the possibility to quantify this uncertainty is particularly important since it allows dealing with crustal seismicity, which is generally less constrained than subduction seismicity, for which it is customary in several TWS worldwide to assume a pure thrust faulting occurring at a depth of the subduction interface corresponding to the epicentral location.…”

Section: Toward a Tsunami Warning Based On Real-time Probabilistic Tsunami Forecastmentioning

confidence: 99%

Tsunami risk management for crustal earthquakes and non-seismic sources in Italy

et al. 2021

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Destructive tsunamis are most often generated by large earthquakes occurring at subduction interfaces, but also other “atypical” sources—defined as crustal earthquakes and non-seismic sources altogether—may cause significant tsunami threats. Tsunamis may indeed be generated by different sources, such as earthquakes, submarine or coastal landslides, volcano-related phenomena, and atmospheric perturbations. The consideration of atypical sources is important worldwide, but it is especially prominent in complex tectonic settings such as the Mediterranean, the Caribbean, or the Indonesian archipelago. The recent disasters in Indonesia in 2018, caused by the Palu-Sulawesi magnitude Mw 7.5 crustal earthquake and by the collapse of the Anak-Krakatau volcano, recall the importance of such sources. Dealing with atypical sources represents a scientific, technical, and computational challenge, which depends on the capability of quantifying and managing uncertainty efficiently and of reducing it with accurate physical modelling. Here, we first introduce the general framework in which tsunami threats are treated, and then we review the current status and the expected future development of tsunami hazard quantifications and of the tsunami warning systems in Italy, with a specific focus on the treatment of atypical sources. In Italy, where the memory of historical atypical events like the 1908 Messina earthquake or the relatively recent 2002 Stromboli tsunami is still vivid, specific attention has been indeed dedicated to the progressive development of innovative strategies to deal with such atypical sources. More specifically, we review the (national) hazard analyses and their application for coastal planning, as well as the two operating tsunami warning systems: the national warning system for seismically generated tsunamis (SiAM), whose upstream component—the CAT-INGV—is also a Tsunami Service Provider of the North-eastern Atlantic, the Mediterranean and connected seas Tsunami Warning System (NEAMTWS) coordinated by the Intergovernmental Coordination Group established by the Intergovernmental Oceanographic Commission (IOC) of UNESCO, and the local warning system for tsunamis generated by volcanic slides along the Sciara del Fuoco of Stromboli volcano. Finally, we review the state of knowledge about other potential tsunami sources that may generate significant tsunamis for the Italian coasts, but that are not presently considered in existing tsunami warning systems. This may be considered the first step towards their inclusion in the national tsunami hazard and warning programs.

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“…Other characteristics of tsunami earthquakes include their slow rupture velocity and long rupture duration (Kanamori, 1972). It is typically thought that they rupture the shallowest part of the subduction interface (Lay et al, 2012), where the rocks contain many fluids and are velocity-strengthening and compliant (Bilek and Lay, 1999;Faulkner et al, 2011;Sahakian et al, 2019). Since tsunami earthquakes could pose an even larger, unexpected hazard than regular tsunamigenic earthquakes, studies have typically focused on the possible mechanisms behind tsunami earthquakes and which type of subduction setting might be more prone to produce them (Polet and Kanamori, 2000;Bilek and Lay, 2002;Geersen, 2019).…”

Section: Introductionmentioning

confidence: 99%

Investigating global correlations between tsunami, earthquake, and subduction zone characteristics

Zelst¹,

Brizzi²,

Rijsingen³

et al. 2022

Preprint

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Tsunamigenic earthquakes pose a large hazard in subduction zones, but it is currently unclear in which - if any - tectonic setting they preferentially occur. We compile the Subduction Nature & Interconnected Tsunamigenic earthquake Characteristics (SNITCH) database with parameters on the geodynamics, megathrust seismicity, and tsunami characteristics for tsunamis caused by earthquakes in all subduction zones. We use a bivariate regression analysis to detect possible relationships between the tsunamigenic earthquake characteristics of a subduction zone and its interplate seismicity, as well as its geometric, structural, and kinematic parameters. We focus our analysis on the normalised number of tsunamigenic earthquakes Nt. The bivariate analysis does not reveal any significant correlations between Nt and the seismogenic zone geometry of the megathrust. However, we do find correlations between Nt and the megathrust seismicity and tectonic parameters characterising a subduction zone. We employ a multivariate Fisher analysis on the tectonic parameters to see which combinations best distinguish the subduction zone segments in which relatively many and few tsunamis occurred. We find that the type of margin (i.e., erosional or accretionary), the trench-normal component of the subduction and convergence velocity, the amount of sediments at the trench and the roughness of the incoming plate are the most important parameters to achieve this. Therefore, tsunamigenic earthquakes may be more prone to occur in tectonic settings where plates subduct relatively fast beneath a sediment-starved, erosional margin. A complex, shallow subduction interface, characterised by multiple faults and fractures that arise at a margin with little trench sediments to smooth subducting plate topography, could account for the larger number of tsunamigenic earthquakes. These results could have implications for hazard assessment.

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Weak Near‐Field Behavior of a Tsunami Earthquake: Toward Real‐Time Identification for Local Warning

Cited by 17 publications

References 37 publications

Near‐Field Effects of Earthquake Rupture Velocity Into Tsunami Runup Heights

Near‐Field Effects of Earthquake Rupture Velocity Into Tsunami Runup Heights

Tsunami risk management for crustal earthquakes and non-seismic sources in Italy

Investigating global correlations between tsunami, earthquake, and subduction zone characteristics

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