Tsunami and Seismic Damage Caused by the Earthquake Off Iquique, Chile, in April, 2014

On Tuesday, April 1, 2014, at 8:46 p.m. local time in Chile, a subduction earthquake of Mw 8.2 occurred about 100[Formula: see text]km northwest of the city of Iquique, where the Nazca plate subducts beneath the South American plate. This earthquake triggered a tsunami, which hit coastal areas in northern Chile. A joint Japan–Chile team conducted a post-tsunami field survey to measure the height of the tsunami traces and to investigate the damage caused by the earthquake and tsunami. Based on measurements of the tsunami traces, it is estimated that a tsunami 3–4[Formula: see text]m in height hit the coast from Arica, which is near the border between Chile and Peru, to Patache, south of Iquique, a straight-line distance of approximately 260[Formula: see text]km. The tsunami caused only minor inundations near shorelines, and caused no damage to buildings because living spaces were higher than the tsunami run-up height. Seismic damage was more extensive than that caused by the tsunami, especially in Iquique, and included the destruction of houses, buildings, and other infrastructure. It also ignited fires. In the Port of Iquique, a wharf, before earthquake-resistant improvements were implemented, was destroyed by the strong ground motions that resulted from the earthquake.

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Measuring the seismic risk along the Nazca-Southamerican subduction front: Shannon entropy and mutability

10.5194/nhess-2019-309 ◽

2019 ◽

Author(s):

Eugenio E. Vogel ◽

Felipe G. Brevis ◽

Denisse Pastén ◽

Víctor Muñoz ◽

Rodrigo A. Miranda ◽

...

Keyword(s):

Shannon Entropy ◽

Seismic Risk ◽

Background Activity ◽

Large Earthquake ◽

South American ◽

The South ◽

Nazca Plate ◽

South American Plate ◽

Major Earthquake ◽

Similarities And Differences

Abstract. Four geographical zones are defined along the trench that is formed due to the subduction of the Nazca Plate underneath the South American plate; they are denoted A, B, C and D from North to South; zones A, B and D have had a major earthquake after 2010 (8.0), while zone C has not, thus offering a contrast for comparison. For each zone a sequence of intervals between consecutive seisms with magnitudes ≥ 3.0 is formed and then characterized by Shannon entropy and mutability. These methods show correlation after a major earthquake in what is known as the aftershock regime but they show independence otherwise. Exponential adjustments for these parameters reveal that mutability offers a wider range for the parameters characterizing the recovery to the values of the parameters defining the background activity for each zone before a large earthquake. It is found that the background activity is particularly high for zone A, still recovering for Zone B, reaching values similar to those of Zone A in the case of Zone C (without recent major earthquake) and oscillating around moderate values for Zone D. It is discussed how this can be an indication for more risk of an important future seism in the cases of Zones A and C. The similarities and differences between Shannon entropy and mutability are discussed and explained.

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Hydrodynamics of Palu Bay during the Event of 2018 Palu Earthquake and Tsunami

BULLETIN OF THE MARINE GEOLOGY ◽

10.32693/bomg.35.1.2020.658 ◽

2020 ◽

Vol 35 (1) ◽

Author(s):

Semeidi Husrin ◽

Fatimah Yasmin Azahra ◽

Joko Prihantono ◽

Armyanda Tussadiah ◽

Rizal Abida

Keyword(s):

Arrival Time ◽

High Tide ◽

Hydrodynamic Characteristics ◽

Submarine Landslides ◽

Tsunami Simulation ◽

Sea Levels ◽

Run Up ◽

Tsunami Run Up ◽

2018 Sulawesi Earthquake ◽

The City

The devastation of coastal area in Palu Bay few minutes after the September 28th, 2018 Sulawesi earthquake showed high variation of tsunami arrival time as well as the tsunami run-up and inundation. Recent findings showed that both local submarine landslides and the normal-slip components inside the Palu Bay may contribute to the generation of tsunami. However, the fact that the event occurred during high tide, the hydrodynamic characteristics of this narrow bay and their role in the dynamics of the generated of tsunami were unknown. Hydrodynamics simulation (Mike21-flow model) using the latest available bathymetry field data (the 2018 deep water of the Indonesian navy data and 2015 shallow water of the BIG data) was conducted to investigate the variation of sea levels and tidal currents within the bay during the event of earthquake and tsunami or within the first 8 minutes timeframe. Results showed that significant increase of water elevation up to 6 cm and current velocity up to 1 cm/s directed towards the city of Palu were observed that may contribute to the dynamics of the tsunami e.g. the speed of tsunami arrival time and the transformation of tsunami. Therefore, considering that multiple tsunami arrivals were in few minutes after the earthquakes, the hydrodynamics of Palu Bay during the event should also be considered in future tsunami simulation scenarios.

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Measuring the seismic risk along the Nazca-Southamerican subduction front: Shannon entropy and mutability

10.5194/nhess-2020-86 ◽

2020 ◽

Author(s):

Eugenio E. Vogel ◽

Felipe G. Brevis ◽

Denisse Pastén ◽

Víctor Muñoz ◽

Rodrigo A. Miranda ◽

...

Keyword(s):

Shannon Entropy ◽

Seismic Risk ◽

Background Activity ◽

Large Earthquake ◽

South American ◽

Nazca Plate ◽

South American Plate ◽

Major Earthquake ◽

Similarities And Differences ◽

Set Up

Abstract. Four geographical zones are deﬁned along the trench that is formed due to the subduction of the Nazca Plate underneath the South American plate; they are denoted A, B, C and D from North to South; zones A, B, and D had a major earthquake after 2010 (Magnitude over 8.0), while zone C has not, thus oﬀering a contrast for comparison. For each zone a sequence of intervals between consecutive seisms with magnitudes ≥ 3.0 is set up and then characterized by Shannon entropy and mutability. These methods show correlation after a major earthquake in what is known as the aftershock regime, but show independence otherwise. Exponential adjustments for these parameters reveal that mutability oﬀers a wider range for the parameters characterizing the recovery compared to the values of the parameters deﬁning the background activity for each zone before a large earthquake. It is found that the background activity is particularly high for zone A, still recovering for zone B, reaching values similar to those of zone A in the case of zone C (without recent major earthquake) and oscillating around moderate values for zone D. It is discussed how this can be an indication for more risk for an important future seism in the cases of zones A and C. The similarities and diﬀerences between Shannon entropy and mutability are discussed and explained.

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The nature of the North-South change of the magnitude of tectonic shortening in Central Andes at Altiplano-Puna latitudes: a thermomechanical modeling approach.

10.5194/egusphere-egu2020-8177 ◽

2020 ◽

Author(s):

Michaël Pons ◽

Stephan Sobolev

Keyword(s):

Cross Sections ◽

Pure Shear ◽

Foreland Basin ◽

Central Andes ◽

South American ◽

Nazca Plate ◽

South American Plate ◽

The Andes ◽

Subduction System ◽

Roll Back

The Andean orogeny is a subduction-type orogeny, the oceanic Nazca Plate sinks under the continental South American Plate. While the subduction has been active since ~180 Ma, the shortening of the Andes initiated at ~50 Ma or less.In a oceanic-continental subduction system, the absolute velocity of the overriding-plate (OP) largely controls the style of subduction (stable, advancing, retreating), the geometry of the slab (dipping angle, curvature) and the style of deformation (shortening or spreading) within the OP. In the case of the Central Peru-Chile subduction, the South American plate is advancing westwards whereas the Nazca plate is anchored into the transition zone (~660 km). As a consequence, the trench is forced to retreat and the Nazca plate to roll-back. The dip of the slab decreases meanwhile the Andes experienced a maximum shortening of ~300 km at ~19-21&#176;S latitudes.Previous study have shown that the strain localizes within areas of low strength and low gravitational potential of energy. In central Andes, weakening mechanisms of the OP such as lithospheric delamination have intensified the magnitude of tectonic shortening and contributed to formation of the Altiplano-Puna plateau. The deformation between the plateau and the foreland occurs in the form of pure shear or simple shear and is expressed in terms of different tectonic styles in the foreland basin, thick-skinned (e.g the Puna) and thin-skinned (e.g the Altiplano), respectively. Nevertheless, the influence of the strength variations of the OP on the subduction dynamics in the case of the central Andes has been poorly explored so far. Our hypothesis is that lateral variations of OP strength result in variable rates of trench roll-back. To test it, we have built 2D high-resolution E-W cross sections along the Altiplano and Puna latitudes (12-27&#176;S) including the subduction of the Nazca plate. For that purpose, we used the FEM geodynamic code ASPECT. Our model includes visco-plastic rheology in addition to gabbro-eclogite phase transition. These preliminary results contribute to the discussion on the nature of the magnitude of shortening in a subduction system. They are also a first step to derive a 3D model of the entire region and to consider additional surface processes such as erosion, transportation and sedimentation.

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High-resolution modeling of tsunami run-up flooding: a case study of flooding in Kamaishi city, Japan, induced by the 2011 Tohoku tsunami

Natural Hazards and Earth System Science ◽

10.5194/nhess-17-1871-2017 ◽

2017 ◽

Vol 17 (11) ◽

pp. 1871-1883 ◽

Cited By ~ 4

Author(s):

Ryosuke Akoh ◽

Tadaharu Ishikawa ◽

Takashi Kojima ◽

Mahito Tomaru ◽

Shiro Maeno

Keyword(s):

Digital Data ◽

Tsunami Propagation ◽

Terrain Model ◽

2011 Tohoku Tsunami ◽

Inundation Depth ◽

Building Footprint ◽

Run Up ◽

Tsunami Run Up ◽

Tohoku Tsunami ◽

The City

Abstract. Run-up processes of the 2011 Tohoku tsunami into the city of Kamaishi, Japan, were simulated numerically using 2-D shallow water equations with a new treatment of building footprints. The model imposes an internal hydraulic condition of permeable and impermeable walls at the building footprint outline on unstructured triangular meshes. Digital data of the building footprint approximated by polygons were overlaid on a 1.0 m resolution terrain model. The hydraulic boundary conditions were ascertained using conventional tsunami propagation calculation from the seismic center to nearshore areas. Run-up flow calculations were conducted under the same hydraulic conditions for several cases having different building permeabilities. Comparison of computation results with field data suggests that the case with a small amount of wall permeability gives better agreement than the case with impermeable condition. Spatial mapping of an indicator for run-up flow intensity (IF = (hU2)max, where h and U respectively denote the inundation depth and flow velocity during the flood, shows fairly good correlation with the distribution of houses destroyed by flooding. As a possible mitigation measure, the influence of the buildings on the flow was assessed using a numerical experiment for solid buildings arrayed alternately in two lines along the coast. Results show that the buildings can prevent seawater from flowing straight to the city center while maintaining access to the sea.

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High-resolution modeling of tsunami run-up flooding: A case study of flooding in Kamaishi City, Japan, induced by the 2011 Tohoku Tsunami

10.5194/nhess-2017-222 ◽

2017 ◽

Author(s):

Ryosuke Akoh ◽

Tadaharu Ishikawa ◽

Takashi Kojima ◽

Mahito Tomaru ◽

Shiro Maeno

Keyword(s):

Digital Data ◽

Tsunami Propagation ◽

Terrain Model ◽

2011 Tohoku Tsunami ◽

Building Footprint ◽

New Treatment ◽

Run Up ◽

Tsunami Run Up ◽

Tohoku Tsunami ◽

The City

Abstract. Run-up processes of 2011 Tohoku Tsunami into the city of Kamaishi, Japan, were simulated numerically using 2D shallow equations with a new treatment of building footprints. The model imposes the internal hydraulic condition of permeable/impermeable walls at the building footprint outline on unstructured triangular meshes. Digital data of the building footprint approximated by polygons were overlaid on a 1.0 m resolution terrain model. The hydraulic boundary conditions were ascertained by conventional tsunami propagation calculation from the seismic center to nearshore areas. Run-up flow calculations were conducted under the same hydraulic conditions for several cases with different building permeabilities. Comparison of computation results with field data suggests that the case with a small amount of wall permeability gives better agreement than the case of impermeable condition. Spatial mapping of an indicator for run-up flow intensity (Z = Umax × Hmax) shows fairly good correlation with the distribution of houses destroyed by flooding. Results of numerical experiments show that concrete buildings arrayed alternately in two lines can prevent seawater from flowing straight to the city center while maintaining access to the sea. The Z value was significantly lower on streets where many houses were destroyed by the 2011 Tohoku Tsunami.

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GNSS Constraints to Active Tectonic Deformations of the South American Continental Margin in Ecuador

Sensors ◽

10.3390/s21124003 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4003

Author(s):

José Tamay ◽

Jesús Galindo-Zaldivar ◽

John Soto ◽

Antonio J. Gil

Keyword(s):

Subduction Zone ◽

Main Tool ◽

South American ◽

The South ◽

Nazca Plate ◽

South American Plate ◽

The North ◽

The Pacific ◽

Active Tectonic ◽

Plate Subduction

GNSS observations constitute the main tool to reveal Earth’s crustal deformations in order to improve the identification of geological hazards. The Ecuadorian Andes were formed by Nazca Plate subduction below the Pacific margin of the South American Plate. Active tectonic-related deformation continues to present, and it is constrained by 135 GPS stations of the RENAGE and REGME deployed by the IGM in Ecuador (1995.4–2011.0). They show a regional ENE displacement, increasing towards the N, of the deformed North Andean Sliver in respect to the South American Plate and Inca Sliver relatively stable areas. The heterogeneous displacements towards the NNE of the North Andean Sliver are interpreted as consequences of the coupling of the Carnegie Ridge in the subduction zone. The Dolores–Guayaquil megashear constitutes its southeastern boundary and includes the dextral to normal transfer Pallatanga fault, that develops the Guayaquil Gulf. This fault extends northeastward along the central part of the Cordillera Real, in relay with the reverse dextral Cosanga–Chingual fault and finally followed by the reverse dextral Sub-Andean fault zone. While the Ecuadorian margin and Andes is affected by ENE–WSW shortening, the easternmost Manabí Basin located in between the Cordillera Costanera and the Cordillera Occidental of the Andes, underwent moderate ENE–WSW extension and constitutes an active fore-arc basin of the Nazca plate subduction. The integration of the GPS and seismic data evidences that highest rates of deformation and the highest tectonic hazards in Ecuador are linked: to the subduction zone located in the coastal area; to the Pallatanga transfer fault; and to the Eastern Andes Sub-Andean faults.

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NEAR-FIELD TSUNAMI HAZARD MAP PADANG, WEST SUMATRA: UTILIZING HIGH RESOLUTION GEOSPATIAL DATA AND RESEASONABLE SOURCE SCENARIOS

Coastal Engineering Proceedings ◽

10.9753/icce.v32.management.26 ◽

2011 ◽

Vol 1 (32) ◽

pp. 26 ◽

Cited By ~ 8

Author(s):

Torsten Schlurmann ◽

Widjo Kongko ◽

Nils Goseberg ◽

Danny Hilman Natawidjaja ◽

Kerry Sieh

Keyword(s):

Near Field ◽

Tsunami Hazard ◽

Tsunami Propagation ◽

Inundation Area ◽

Western Shore ◽

Run Up ◽

And Performance ◽

Evacuation Routes ◽

Tsunami Run Up ◽

The City

Near-field tsunami propagation both in shallow water environments and bore-like wave propagation on land are conducted in this study to obtain fundamental knowledge on the tsunami hazard potential in the city of Padang, Western Sumatra, Republic of Indonesia. As the region proves a huge seismic moment deficit which has progressively accumulated since the last recorded major earthquakes in 1797 and 1833, this investigation focuses on most reasonable seismic sources and possibly triggered nearshore tsunamis in order to develop upgraded disaster mitigations programs in this densely-populated urban agglomeration located on the western shore of Sumatra Island. Observations from continuous Global Positioning Satellite (cGPS) systems and supplementary coral growth studies confirm a much greater probability of occurrence that a major earthquake and subsequent tsunami are likely to strike the region in the near future. Newly surveyed and processed sets of geodata have been collected and used to progress most plausible rupture scenarios to approximate the extent and magnitudes of a further earthquake. Based upon this novel understanding, the present analysis applies two hydronumerical codes to simulate most probable tsunami run-up and subsequent inundations in the city of Padang in very fine resolution. Run-up heights and flow-depths are determined stemming from these most plausible rupture scenarios. Evaluation of outcome and performance of both numerical tools regarding impacts of surge flow and bore-like wave fronts encountering the coast and inundating the city are thoroughly carried out. Results are discussed not only for further scientific purposes, i.e. benchmark tests, but also to disseminate main findings to responsible authorities in Padang with the objective to distribute the most probable dataset of plausible tsunami inundations as well as to address valuable insights and knowledge for effective counter measures, i.e. evacuation routes and shelter building. Following evacuation simulations based on rational assumptions and simplifications reveal a most alerting result as about 260.000 people are living in the highly exposed potential tsunami inundation area in the city of Padang of which more than 90.000 people will need more than 30 min. to evacuate to safe areas.

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What drives orogeny in the Andes?

Geology ◽

10.1130/g21557ar.1 ◽

2005 ◽

Vol 33 (8) ◽

pp. 617-620 ◽

Cited By ~ 36

Author(s):

S.V. Sobolev ◽

A.Y. Babeyko

Keyword(s):

Friction Coefficient ◽

Crustal Structure ◽

South American ◽

The South ◽

Nazca Plate ◽

South American Plate ◽

The Andes ◽

Continental Lower Crust ◽

Sediment Cover

Abstract The Andes, the world's second highest orogenic belt, were generated by the Cenozoic tectonic shortening of the South American plate margin overriding the subducting Nazca plate. We use a coupled thermomechanical numerical modeling technique to identify factors controlling the intensity of the tectonic shortening. From the modeling, we infer that the most important factor was accelerated westward drift of the South American plate; changes in the subduction rate were less important. Other important factors are crustal structure of the overriding plate and shear coupling at the plates' interface. The model with a thick (40–45 km at 30 Ma) South American crust and relatively high friction coefficient (0.05) at the Nazca–South American interface generates >300 km of tectonic shortening during 30–35 m.y. and replicates the crustal structure and evolution of the high central Andes. The model with an initially thinner (<40 km) continental crust and lower friction coefficient (<0.015) results in <40 km of South American plate shortening, replicating the situation in the southern Andes. Our modeling also demonstrates the important role of the processes leading to mechanical weakening of the overriding plate during tectonic shortening, such as lithospheric delamination, triggered by the gabbro-eclogite transformation in the thickened continental lower crust, and mechanical failure of the sediment cover at the shield margin.

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The Run up Tsunami Modeling in Bengkulu using the Spatial Interpolation of Kriging Technique

Forum Geografi ◽

10.23917/forgeo.v28i2.427 ◽

2014 ◽

Vol 28 (2) ◽

Cited By ~ 2

Author(s):

Yulian Fauzi ◽

Suwarsono Suwarsono ◽

Zulfia Memi Mayasari

Keyword(s):

Land Use ◽

Interpolation Method ◽

Spatial Modelling ◽

Kriging Interpolation ◽

Tsunami Inundation ◽

Kriging Interpolation Method ◽

Run Up ◽

Tsunami Run Up ◽

The City ◽

Flooded Areas

This research aims to design a tsunami hazard zone with the scenario of tsunami run-up height variation based on land use, slope and distance from the shoreline. The method used in this research is spatial modelling with GIS via Ordinary Kriging interpolation technique. Kriging interpolation method that is the best in this study is shown by Circular Kriging method with good semivariogram and RMSE values which are small compared to other RMSE kriging methods. The results shows that the area affected by the tsunami inundation run-up height, slope and land use. In the run-up to 30 meters, flooded areas are about 3,148.99 hectares or 20.7% of the total area of the city of Bengkulu.

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