scholarly journals THE EFFECT OF A SUBMARINE CANYON ON TSUNAMI PROPAGATION IN THE GULF OF ARAUCO, CHILE

2012 ◽  
Vol 1 (33) ◽  
pp. 5 ◽  
Author(s):  
Rafael Aranguiz
Keyword(s):  
River Mouth ◽  
Submarine Canyon ◽  
Eastern Coast ◽  
Wave Direction ◽  
Tsunami Propagation ◽  
Eastern Side ◽  
Nested Grids ◽  
The 2010 Chile Tsunami ◽  
Chile Tsunami ◽  
Santa Maria

The 2010 Chile tsunami affected the entire coast of the Biobio Region, where several bays were flooded, and seawater surged hundreds of meters into rivers. However, no inundation occurred in the 2km wide Biobio River, located at the northern entrance of the Gulf of Arauco. Likewise, minimal inundation (less than 2m) was found on the gulf’s eastern coast, just south of the river mouth. The study was done by means of numerical simulation with TUNAMI code. Four (4) nested grids with 81”, 27”, 9” and 3” resolution were defined. Several scenarios were simulated, including the 1730, 1835, 1960 and 2010 events. The first two scenarios considered only a uniform rupture zone, while the others were defined using non-uniform initial condition. Another set of simulations were run without the presence of the island and with a modified bathymetry, so that its effect on tsunami propagation could be studied. It can be concluded that the Biobio canyon is very important in tsunami propagation in the Gulf of Arauco. There is a mitigation effect on the eastern side of the Gulf due to the refraction and dispersion generated by its presence. The change in wave direction is enhanced due to wave diffraction generated by the Santa María Island, causing the wave fronts to move in a north-south direction, preventing severe damage to the eastern side. However a direct impact of the tsunami in the southern end of the Gulf can be observed.

scholarly journals Risk factors and perceived restoration in a town destroyed by the 2010 Chile tsunami

2017 ◽  
Vol 17 (5) ◽  
pp. 721-734 ◽  
Author(s):  
Carolina Martínez ◽  
Octavio Rojas ◽  
Paula Villagra ◽  
Rafael Aránguiz ◽  
Katia Sáez-Carrillo
Keyword(s):  
Risk Factors ◽  
Large Earthquake ◽  
Similar Degree ◽  
Restorative Environments ◽  
Reconstruction Process ◽  
Maule Earthquake ◽  
Nested Grids ◽  
Household Incomes ◽  
The 2010 Chile Tsunami ◽  
Chile Tsunami

Abstract. A large earthquake and tsunami took place in February 2010, affecting a significant part of the Chilean coast (Maule earthquake, Mw of 8.8). Dichato (37° S), a small town located on Coliumo Bay, was one of the most devastated coastal areas and is currently under reconstruction. Therefore, the objective of this research is to analyze the risk factors that explain the disaster in 2010, as well as perceived restoration 6 years after the event. Numerical modeling of the 2010 Chile tsunami with four nested grids was applied to estimate the hazard. Physical, socioeconomic and educational dimensions of vulnerability were analyzed for pre- and post-disaster conditions. A perceived restoration study was performed to assess the effects of reconstruction on the community. It was focused on exploring the capacity of newly reconstructed neighborhoods to provide restorative experiences in case of disaster. The study was undertaken using the perceived restorativeness scale. The vulnerability variables that best explained the extent of the disaster were housing conditions, low household incomes and limited knowledge about tsunami events, which conditioned inadequate reactions to the emergency. These variables still constitute the same risks as a result of the reconstruction process, establishing that the occurrence of a similar event would result in a similar degree of devastation. For post-earthquake conditions, it was determined that all neighborhoods have the potential to be restorative environments soon after a tsunami. However, some neighborhoods are still located in areas devastated by the 2010 tsunami and again present high vulnerability to future tsunamis.

A multi-scenario assessment of the seismogenic tsunami hazard for Bangladesh

2019 ◽  
Vol 11 (2) ◽  
pp. 156-168
Author(s):  
Janaka J. Wijetunge
Keyword(s):  
Subduction Zones ◽  
Submarine Canyon ◽  
Tsunami Hazard ◽  
Seismic Zone ◽  
Tsunami Propagation ◽  
Content Type ◽  
Arrival Times ◽  
Tsunami Waves ◽  
Scenario Assessment ◽  
Seismic Scenarios

Purpose This paper aims to describe a multi-scenario assessment of the seismogenic tsunami hazard for Bangladesh from active subduction zones in the Indian Ocean region. Two segments of the Sunda arc, namely, Andaman and Arakan, appear to pose a tsunamigenic seismic threat to Bangladesh. Design/methodology/approach High-resolution numerical simulations of tsunami propagation toward the coast of Bangladesh have been carried out for eight plausible seismic scenarios in Andaman and Arakan subduction zones. The numerical results have been analyzed to obtain the spatial variation of the maximum tsunami amplitudes as well as tsunami arrival times for the entire coastline of Bangladesh. Findings The results suggest that the tsunami heights are amplified on either side of the axis of the submarine canyon which approaches the nearshore sea off Barisal in the seaboard off Sundarban–Barisal–Sandwip. Moreover, the computed tsunami amplitudes are comparatively higher north of the latitude 21.5o in the Teknaf–Chittagong coastline. The calculated arrival times indicate that the tsunami waves reach the western half of the Sundarban–Barisal–Sandwip coastline sooner, while shallow water off the eastern half results in a longer arrival time for that part of the coastline, in the event of an earthquake in the Andaman seismic zone. On the other hand, most parts of the Chittagong–Teknaf coastline would receive tsunami waves almost immediately after an earthquake in the northern segment of the Arakan seismic zone. Originality/value The present assessment includes probabilistic measures of the tsunami hazard by incorporating several probable seismic scenarios corresponding to recurrence intervals ranging from 25 years to over 1,000 years.

scholarly journals Risk Factors and Perceived Restoration in a Town Destroyed by the 2010 Chile Tsunami

2016 ◽  
Author(s):  
Carolina Martínez ◽  
Octavio Rojas ◽  
Paula Villagra ◽  
Rafael Aránguiz ◽  
Katia Sáez-Carrillo
Keyword(s):  
Risk Factors ◽  
Principal Component ◽  
Large Earthquake ◽  
Similar Degree ◽  
Restorative Environments ◽  
Reconstruction Process ◽  
Maule Earthquake ◽  
The 2010 Chile Tsunami ◽  
Chile Tsunami ◽  
Post Disaster

Abstract. A large earthquake and tsunami took place in February 2010, affecting a significant part of the Chilean coast (Maule earthquake (Mw = 8.8). Dichato (37° S), a small town located on Coliumo Bay, was one of the most devastated coastal places and is currently under reconstruction. Therefore, the risk factors which explain the disaster at that time as well as perceived restoration 6 years after the event were analyzed in the present paper. Numerical modeling of the 2010 Chile tsunami with four nested grids was applied to estimate the hazard. Physical, socio-economic and educational dimensions of vulnerability were analyzed for pre- and post-disaster conditions. A perceived restoration study was performed to assess the effects of reconstruction on the community and a principal component analysis was applied for post-disaster conditions. The vulnerability factors that best explained the extent of the disaster were housing conditions, low household incomes and limited knowledge about tsunami events, which conditioned inadequate reactions to the emergency. These factors still constitute the same risks as a result of the reconstruction process, establishing that the occurrence of a similar event would result in a similar degree of disaster. For post-earthquake conditions, it was determined that all neighborhoods have the potential to be restorative environments soon after a tsunami. However, some neighborhoods are still located in areas devastated by the 2010 tsunami and present a high vulnerability to future tsunamis. Therefore, it may be stated that these areas will probably be destroyed again in case of future events.

scholarly journals Field Observation of Sand Movement around Submarine Canyon Offshore of Morito River Mouth

2009 ◽  
Vol 65 (1) ◽  
pp. 636-640
Author(s):  
Jun-ichi HOSOKAWA ◽  
Tomo SHIOIRI ◽  
Harumi TAKAO ◽  
Kazue AKITA ◽  
Takaaki UDA ◽  
...  
Keyword(s):  
Field Observation ◽  
River Mouth ◽  
Submarine Canyon ◽  
Sand Movement

Seafloor Erosion induced by overbanking flow derived by a 2.5D high resolution sparker seismic dataset, uppermost Kaoping Submarine Canyon, southwestern offshore Taiwan

2020 ◽  
Author(s):  
Wei-Chung Hsiao ◽  
Yi-Ching Yeh ◽  
Yen-Yu Cho ◽  
Shu-Kun Hsu
Keyword(s):  
River Mouth ◽  
Seismic Source ◽  
Submarine Canyon ◽  
Point Of View ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Match Filter ◽  
The North ◽  
Manila Trench ◽  
Marine Seismic

<p>The Kaoping submarine canyon (KPSC) originates from Kaoping River, southwestern Taiwan that extends about 250 kilometers long from the Kaoping River mouth down to the Manila Trench. It can be divided into three major sections: upper reach (meandering), middle reach (NW-SE trending and V-shaped canyon) and lower reach (meandering). Based on recent a swath bathymetric data in the uppermost KPSC, an obvious seafloor depression can be observed in the eastern bank of the canyon. The eastern bank of the canyon reveals about 30-50 meters in average lower than western bank. The mechanism is blurred. In this study, to investigate fine sedimentary structures in 3D point of view, we used marine sparker seismic method. The seismic source frequency varies from 100 to 1200 Hz which can provide about 0.6 meters vertical resolution (i.e. central frequency 600 Hz and 1,600 m/s Vp). We have collected 75 in-lines across the canyon and 3 cross-lines perpendicular to the in-line. The data went through conventional marine seismic data processing procedures such as bad trace kill, band-pass filter, 2D geometry settings, NMO stacking, swell correction, match filter and predictive deconvolution. The 2D dataset was reformatted by applying 3D geometry settings to create a 3D seismic cube. The result shows that a wide incision channel was first found in the north of Xiaoliuchiu islet. Through depth, this channel becomes two narrower channels divided by a mud diapir. This down cutting can be traced down to transgressive sequence in prior to LGM (Last Glacial Maximum). In addition, a deep-towed sub-bottom profiler shows an obvious down-lapping structures heading off canyon that indicates over banking flow may be a key role to cause this erosional event.</p>

scholarly journals Systematic comparison of different numerical approaches for tsunami simulations at the Chilean coast as part of the RIESGOS project

2020 ◽  
Author(s):  
Sven Harig ◽  
Natalia Zamora ◽  
Alejandra Gubler ◽  
Natalja Rakowsky
Keyword(s):  
Numerical Models ◽  
Tide Gauge ◽  
Tsunami Propagation ◽  
Chilean Coast ◽  
The Andes ◽  
Source Determination ◽  
Probabilistic Study ◽  
Nested Grids ◽  
Element Approach ◽  
Numerical Approaches

<p>There is a growing number of numerical models for tsunami propagation and inundation available, based on different spatial discretizations and numerical approaches. Since simulations carried out with such models are used to generate warning products in an early warning context, it is crucial to investigate differences emerging from the chosen algorithms for simulation and warning product determination. Uncertainties regarding the source determination within the first minutes after a tsunami generation might be of major concern for an appropriate warning at the coast, still, the sensitivity of warning products with respect to pre-computed simulation database contents or on-the-fly calculations are of crucial importance as well.</p><p>In this study, we investigate the performance of three models (TsunAWI, HySEA, COMCOT) in the oceanic region offshore central and northern Chile with inundation studies in Valparaíso and Viña del Mar. The investigation forms part of the tsunami component in the RIESGOS project dealing more general with multi hazard assessments in the Andes region. The numerical implementation of the models include both a finite element approach with triangular meshes of variable resolution as well as finite difference implementations with nested grids for the coastal area. The tsunami sources are identical in all models and chosen from an ensemble of events used in an earlier probabilistic study of the region. Additionally, two historic events are considered as well to validate the models against the corresponding measurements.</p><p>We compare results in virtual gauges as well as actual tide gauge locations at the Chilean coast. Inundation areas are determined with high resolution and employing the model specific wetting and drying implementations. We compare the model results and sensitivities with respect to spatial resolution and parameters like bottom friction and bathymetry  representation in the varying mesh geometries.</p>

scholarly journals Effects of bottom topography on dynamics of river discharges in tidal regions: case study of twin plumes in Taiwan Strait

2014 ◽  
Vol 11 (2) ◽  
pp. 1149-1189
Author(s):  
K. A. Korotenko ◽  
A. A. Osadchiev ◽  
P. O. Zavialov ◽  
R.-C. Kao ◽  
C.-F. Ding
Keyword(s):  
Bottom Topography ◽  
River Mouth ◽  
Taiwan Strait ◽  
Ocean Model ◽  
Tidal Mixing ◽  
Eastern Coast ◽  
Spatial And Temporal Variability ◽  
Surface Salinity ◽  
Study Region ◽  
Tracking Model

Abstract. The Princeton Ocean Model is used to investigate the intratidal variability of currents and turbulent mixing and their impact on the characteristics and evolution of the plumes of two neighboring rivers, the Zhuoshui River and the Wu River, at the central eastern coast of Taiwan Strait. The two estuaries are located close to each other and their conditions are similar in many respects, and yet the two plumes exhibit significantly different behavior. We explain this through differences of the bottom topography in the areas adjacent to the two river mouths. The Zhuoshui River runs into a shallow area that is permanently exposed to strong tidal mixing, while the Wu River mouth is located in a deeper, stratified area outside the region of intense mixing. This destruction of the plume by tidal mixing is confirmed by the results of numerical modeling with POM. The spatial and temporal variability of turbulent kinetic energy and its production rate in the study region, as well as the horizontal diffusivity, are analyzed with the emphasis given to the dependence of the turbulence parameters on the bottom topography on the one hand and their influence on the river plumes on the other. Further, we use a Lagrangian particle tracking model in combination with POM to investigate the effect of the tidal wetting-and-drying (WAD) of land taking place near the Zhuoshui estuary, and demonstrate that WAD leads to significant reduction of the plume extent and surface salinity deficit near the river mouth. We use observational data from a short field campaign in the study area to tune and validate the model experiments.

Monitoring and Modelling of ionospheric disturbances by means of GRACE, GOCE and Swarm in-situ observations

2021 ◽  
Author(s):  
Michael Schmidt ◽  
Andreas Goss ◽  
Eren Erdogan
Keyword(s):  
Lower Atmosphere ◽  
Ionospheric Disturbances ◽  
Tsunami Propagation ◽  
Ka Band ◽  
Leo Satellites ◽  
Vertical Displacements ◽  
Grace Satellites ◽  
Langmuir Probe Measurements ◽  
The University ◽  
Chile Tsunami

<p>The main objective of the ESA-funded project COSTO (Contribution of Swarm data to the prompt detection of Tsunamis and other natural hazards) is to better characterize, understand and discover coupling processes and interactions between the ionosphere, the lower atmosphere and the Earth’s surface as well as sea level vertical displacements. Together with our project partners from the University of Warmia and Mazury (UWM), the National Observatory of Athens (NOA) and the Universitat Politecnica de Catalunya (UPC) we focus in COSTO to tsunamis that are the result of earthquakes (EQ), volcano eruptions or landslides.</p><p>In the scope of COSTO a roadmap was developed to detect the vertical and horizontal propagation of Travelling Ionospheric Disturbances (TID) in the observations of Low Earth Orbiting (LEO) satellites. Under the assumption that the TIDs triggered by tsunamis behave in approximately the same way for different EQ / tsunami events, this roadmap can be applied also to other events. In this regard, the Tohoku-Oki EQ in 2011 and the Chile EQ in 2015 were studied in detail. The aim of investigating these events is to detect the TIDs in the near vicinity of the propagating tsunami. Thereby, given tsunami propagation models serve as a rough orientation to determine the moments in time and positions for which there is co-location with selected LEO satellites/missions, namely GRACE, GOCE and Swarm. GOCE with an altitude of around 280km and the GRACE satellites with an altitude of around 450km flew over the region where the Tohoku-Oki tsunami was located, about 2.5 hours after the EQ. Using wavelet transform, similar signatures with periods of 10-30 seconds could be detected in the top-side STEC observations of GOCE as well as in the Ka-band observations of GRACE at the time of the overflight. These signatures can be related to the gravity wave originating from the tsunami. Similar signatures were detected in the signals from the GRACE Ka-band observations and in the Swarm Langmuir Probe measurements at an altitude of 450 km for the 2015 Chile tsunami. These roadmap studies provided the first opportunity to observe the vertical and horizontal tsunami induced gravity waves in the ionosphere.</p>

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