scholarly journals The 23 June 2020 Mw 7.4 La Crucecita, Oaxaca, Mexico Earthquake and Tsunami: A Rapid Response Field Survey during COVID-19 Crisis

2020 ◽  
Vol 92 (1) ◽  
pp. 26-37 ◽  
Author(s):  
María-Teresa Ramírez-Herrera ◽  
David Romero ◽  
Néstor Corona ◽  
Héctor Nava ◽  
Hamblet Torija ◽  
...  
Keyword(s):  
Field Survey ◽  
Tide Gauge ◽  
Deep Ocean ◽  
Vertical Displacement ◽  
Rapid Response ◽  
Coseismic Deformation ◽  
Response Effort ◽  
Coastal Morphology ◽  
Tsunami Inundation ◽  
Coastal Uplift

Abstract The 23 June 2020 La Crucecita earthquake occurred at 10:29 hr on the coast of Oaxaca in an Mw 7.4 megathrust event at 22.6 km depth and triggered a tsunami recorded at tide gauge stations and a Deep-ocean Assessment and Reporting of Tsunamis off the coast of Mexico. Immediately after the earthquake, a rapid response effort was coordinated by members of the Tsunami and Paleoseismology Laboratory, Universidad Nacional Autónoma de México. Despite the challenges posed by the Coronavirus disease 2019 (COVID-19) pandemic crisis, a postearthquake and post-tsunami field survey went ahead two days after the event. We describe here the details of the rapid response survey of the vertical coseismic deformation, tsunami, geologic effects, and lessons from working in the field during the COVID-19 crisis. We surveyed 44 km along the coast of Oaxaca. Because of the COVID-19 pandemic, some local communities enforced rules of confinement. We solved most of the challenges faced during this crisis by rapidly networking with local organizations prior to surveying. We assessed coseismic uplift by means of mortality caused by vertical displacement of intertidal organisms and resurveying of benchmarks, and we measured tsunami runup. Our results show coastal uplift of 0.53 m near the epicenter and decreasing farther away from it; uplift was up to 0.8 m in areas related to exposure of the coast. Of our values of coastal uplift, about 0.53 m fit well with the 0.55 m of uplift reported by tide gauge data at Huatulco. Coastal uplift and low tide at the time of the event limited the tsunami inundation and runup on the Oaxaca coast. Nevertheless, we found tsunami inundation evidence at four confined coastal sites reaching a maximum runup of 1.5 m. The enclosed morphology of these sites determined higher runup and tsunami inundation. Local coastal morphology effects are not detected in tsunami models lacking detailed bathymetry and topography. This issue needs to be addressed during tsunami hazard assessments.

The 2018 Palu Tsunami: Coeval Landslide and Coseismic Sources

2020 ◽  
Vol 91 (6) ◽  
pp. 3148-3160
Author(s):  
Amy L. Williamson ◽  
Diego Melgar ◽  
Xiaohua Xu ◽  
Christopher Milliner
Keyword(s):  
Survey Data ◽  
Field Survey ◽  
Tide Gauge ◽  
Hazard Analysis ◽  
Strike Slip ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Video Footage ◽  
Run Up ◽  
Tsunami Model

Abstract On 28 September 2018, Indonesia was struck by an MW 7.5 strike-slip earthquake. An unexpected tsunami followed, inundating nearby coastlines leading to extensive damage. Given the traditionally non-tsunamigenic mechanism, it is important to ascertain if the source of the tsunami is indeed from coseismic deformation, or something else, such as shaking induced landsliding. Here we determine the leading cause of the tsunami is a complex combination of both. We constrain the coseismic slip from the earthquake using static offsets from geodetic observations and validate the resultant “coseismic-only” tsunami to observations from tide gauge and survey data. This model alone, although fitting some localized run-up measurements, overall fails to reproduce both the timing and scale of the tsunami. We also model coastal collapses identified through rapidly acquired satellite imagery and video footage as well as explore the possibility of submarine landsliding using tsunami raytracing. The tsunami model results from the landslide sources, in conjunction with the coseismic-generated tsunami, show a greatly improved fit to both tide gauge and field survey data. Our results highlight a case of a damaging tsunami the source of which is a complex mix of coseismic deformation and landsliding. Tsunamis of this nature are difficult to provide warning for and are underrepresented in regional tsunami hazard analysis.

scholarly journals On the Quality of Real-Time Altimeter Gridded Fields: Comparison with In Situ Data

2009 ◽  
Vol 26 (3) ◽  
pp. 556-569 ◽  
Author(s):  
Ananda Pascual ◽  
Christine Boone ◽  
Gilles Larnicol ◽  
Pierre-Yves Le Traon
Keyword(s):  
Real Time ◽  
Sea Level ◽  
Tide Gauge ◽  
Deep Ocean ◽  
Velocity Estimation ◽  
Time Data ◽  
In Situ Data ◽  
Delayed Time

Abstract The timeliness of satellite altimeter measurements has a significant effect on their value for operational oceanography. In this paper, an Observing System Experiment (OSE) approach is used to assess the quality of real-time altimeter products, a key issue for robust monitoring and forecasting of the ocean state. In addition, the effect of two improved geophysical corrections and the number of missions that are combined in the altimeter products are also analyzed. The improved tidal and atmospheric corrections have a significant effect in coastal areas (0–100 km from the shore), and a comparison with tide gauge observations shows a slightly better agreement with the gridded delayed-time sea level anomalies (SLAs) with two altimeters [Jason-1 and European Remote Sensing Satellite-2 (ERS-2)/Envisat] using the new geophysical corrections (mean square differences in percent of tide gauge variance of 35.3%) than those with four missions [Jason-1, ERS/Envisat, Ocean Topography Experiment (TOPEX)/Poseidoninterlaced, and Geosat Follow-On] but using the old corrections (36.7%). In the deep ocean, however, the correction improvements have little influence. The performance of fast delivery products versus delayed-time data is compared using independent in situ data (tide gauge and drifter data). It clearly highlights the degradation of real-time SLA maps versus the delayed-time SLA maps: four altimeters are needed in real time to get the similar quality performance as two altimeters in delayed time (sea level error misfit around 36%, and zonal and meridional velocity estimation errors of 27% and 33%, respectively). This study proves that the continuous improvement of geophysical corrections is very important, and that it is essential to stay above a minimum threshold of four available altimetric missions to capture the main space and time oceanic scales in fast delivery products.

Behavioural observations on the scavenging fauna of the Patagonian slope

1999 ◽  
Vol 79 (6) ◽  
pp. 963-970 ◽  
Author(s):  
Martin A. Collins ◽  
Cynthia Yau ◽  
Conor P. Nolan ◽  
Phil M. Bagley ◽  
Imants G. Priede
Keyword(s):  
Soft Tissues ◽  
Deep Ocean ◽  
Rapid Response ◽  
The Other ◽  
Falkland Islands ◽  
Antimora Rostrata ◽  
Consumption Rates ◽  
Patagonian Toothfish ◽  
Primary Consumers ◽  
Dissostichus Eleginoides

The scavenging fauna of the Patagonian slope (900–1750 m), east of the Falkland Islands was investigated using the Aberdeen University Deep Ocean Submersible (AUDOS), an autonomous baited camera vehicle designed to photograph scavenging fish and invertebrates. The AUDOS was deployed on ten occasions in Falkland waters. Nine experiments were of 10–14 h duration and baited with 800 g of squid and one experiment lasted six days, baited with a 10 kg toothfish (Dissostichus eleginoides). Analysis of photographs revealed considerable patchiness in the composition of the scavenging fauna. Hagfish (Myxine cf. fernholmi) dominated three of the shallower experiments including the 6-d experiment, arriving quickly from down-current, holding station at the bait and consuming the soft tissues first, with consumption rates of up to 200 g h−1. In the other experiments, stone crabs (Lithodidae), the blue-hake (Antimora rostrata) and amphipods were the primary consumers, but the rate of bait consumption was lower. Patagonian toothfish (D. eleginoides) were attracted to the bait at each experiment, but did not attempt to consume the bait. The patchiness in the fauna may be a result of depth, substratum and topography, but in general the rapid response of the scavenging fauna indicates that carrion is rapidly dispersed, with little impact on the local sediment community.

scholarly journals Assessment of the Accuracy of Recent Empirical and Assimilated Tidal Models for the Great Barrier Reef, Australia, Using Satellite and Coastal Data

2019 ◽  
Vol 11 (10) ◽  
pp. 1211 ◽  
Author(s):  
Fardin Seifi ◽  
Xiaoli Deng ◽  
Ole Baltazar Andersen
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Root Mean Square ◽  
Tide Gauge ◽  
Bottom Topography ◽  
Deep Ocean ◽  
Mean Square ◽  
Barrier Reef ◽  
In Situ Data ◽  
The Impact

The latest satellite and in situ data are a fundamental source for tidal model evaluations. In this work, the satellite missions TOPEX/Poseidon, Jason-1, Jason-2 and Sentinel-3A, together with tide gauge data, were used to investigate the performance of recent regional and global tidal models over the Great Barrier Reef, Australia. Ten models, namely, TPXO8, TPXO9, EOT11a, HAMTIDE, FES2012, FES2014, OSUNA, OSU12, GOT 4.10 and DTU10, were considered. The accuracy of eight major tidal constituents (i.e., K1, O1, P1, Q1, M2, S2, N2 and K2) and one shallow water constituent (M4) were assessed based on the analysis of sea-level observations from coastal tide gauges and altimetry data (TOPEX series). The outcome was compared for four different subregions, namely, the coastline, coastal, shelf and deep ocean zones. Sea-level anomaly data from the Sentinel-3A mission were corrected using the tidal heights predicted by each model. The root mean square values of the sea level anomalies were then compared. According to the results, FES2012 compares more favorably to other models with root mean square (RMS) values of 10.9 cm and 7.7 cm over the coastal and shelf zones, respectively. In the deeper sections, the FES2014 model compares favorably at 7.5 cm. In addition, the impact of sudden fluctuations in bottom topography on model performances suggest that a combination of bathymetric variations and proximity to the coast or islands contributes to tidal height prediction accuracies of the models.

scholarly journals Developing fragility functions for the areas affected by the 2009 Samoa earthquake and tsunami

2014 ◽  
Vol 2 (1) ◽  
pp. 1-25
Author(s):  
H. Gokon ◽  
S. Koshimura ◽  
K. Imai ◽  
M. Matsuoka ◽  
Y. Namegaya ◽  
...  
Keyword(s):  
Satellite Images ◽  
Hydrodynamic Force ◽  
Deep Ocean ◽  
Building Damage ◽  
Fragility Functions ◽  
Tsunami Propagation ◽  
Tsunami Inundation ◽  
Field Surveys ◽  
High Resolution Satellite Images ◽  
Tsunami Fragility

Abstract. Fragility functions in terms of flow depth, flow velocity and hydrodynamic force are developed to evaluate structural vulnerability in the areas affected by the 2009 Samoa earthquake and tsunami. First, numerical simulations of tsunami propagation and inundation are conducted to reproduce the features of tsunami inundation. To validate the results, flow depths measured in field surveys and waveforms measured by Deep-ocean Assessment and Reporting of Tsunamis (DART) gauges are utilized. Next, building damage is investigated by manually detecting changes between pre- and post-tsunami high-resolution satellite images. Finally, the data related to tsunami features and building damage are integrated using GIS, and tsunami fragility functions are developed based on the statistical analyses.

scholarly journals The coherence of small island sea-level with the wider ocean: a model study

2012 ◽  
Vol 9 (5) ◽  
pp. 3049-3070
Author(s):  
Joanne Williams ◽  
Christopher W. Hughes
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Deep Ocean ◽  
Ocean Model ◽  
Small Island ◽  
Poor Agreement ◽  
Model Study ◽  
Tide Gauge Measurements ◽  
The Relationship ◽  
Good Agreement

Abstract. Studies comparing tide gauge measurements with sea level from nearby satellite altimetry have shown good agreement for some islands, and poor agreement for others, though no explanation has been offered. Using the 1/12° OCCAM ocean model, we investigate the relationship between sea level at small, open-ocean islands, and offshore sea level. For every such island or seamount in the model, we compare the shallow-water sea level with the steric and bottom pressure variability in a neighboring ring of deep water. We find a latitude-dependent range of frequencies for which off-shore sea level is poorly correlated with island sea level. This poor coherence occurs in a spectral region for which steric signals dominate, but are unable to propagate as baroclinic Rossby waves. This mode of decoupling does not arise because of island topography, as the same decoupling is seen between deep ocean points and surrounding rings.

Field Survey of the 2018 Sulawesi Tsunami: Inundation and Run-up Heights and Damage to Coastal Communities

2019 ◽  
Vol 176 (8) ◽  
pp. 3291-3304 ◽  
Author(s):  
Takahito Mikami ◽  
Tomoya Shibayama ◽  
Miguel Esteban ◽  
Tomoyuki Takabatake ◽  
Ryota Nakamura ◽  
...  
Keyword(s):  
Field Survey ◽  
Coastal Communities ◽  
Tsunami Inundation ◽  
Run Up

scholarly journals The 23 June 2020, Mw 7.4 La Crucecita, Oaxaca, Mexico earthquake and tsunami: A Rapid Response Field Survey during COVID-19 crisis

2020 ◽  
Author(s):  
Maria Teresa Ramirez-Herrera ◽  
David Romero ◽  
Néstor Corona ◽  
Héctor Nava ◽  
Hamblet Torija ◽  
...  
Keyword(s):  
Field Survey ◽  
Rapid Response ◽  
Mexico Earthquake ◽  
Response Field

The Vertical Coseismic Deformation Field of the Samos-Izmir Earthquake (Mw6.9)

2021 ◽  
Author(s):  
Muharrem Hilmi Erkoç ◽  
Seda Özarpacı ◽  
Alpay Özdemir ◽  
Figen Eskiköy ◽  
Efe Turan Ayruk ◽  
...  
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Source Region ◽  
Coseismic Deformation ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Western Turkey ◽  
Tsunami Waves ◽  
Eastern Aegean ◽  
Wave Heights

<p>The Samos-Izmir Earthquake (Mw=6.9) of October 30, 2020 is among the strongest earthquakes that occurred in recent years throughout the Eastern Aegean. The epicenter of this earthquake was 14 km away from Samos Island and 25 km away from Gümüldür-İzmir region. The local tsunami with the wave heights reaching ~2m was triggered by the mainshock. The most affected areas were Sigacik and Akarca in Tukey (Yalciner et. al.,2020) and Vathy Town (NE Samos Island) in Greece (Triantafyllou et. al.,2020).</p><p>In this study, we present an estimation of co-seismic deformations using an indirect approach based on GNSS, InSAR and Tide Gauge data. GNSS time series were used from 25 continuous GNSS stations data obtained from TUSAGA-Aktif in Turkey and NOANET in Greek, and the campaign GNSS measurement for 10 GNSS sites located at the western Turkey coast has been carried out after the earthquake. Moreover, InSAR deformation analyses have been performed using Sentinel-1 data. In addition, relative sea level changes have been analyzed in KOS, PLOMARI, and MENTES tide gauge stations.</p><p>The vertical components of GPS stations have shown 10 cm uplift in Samos Island and 10 cm subsidence in the coast of Turkey. The results of the geodetic (GNSS, InSAR) analysis are consistent with each other. The rise time estimated here may correspond to the time elapsed shortly before the generation of tsunami waves reached up to 6 meters that propagated rapidly and caused significant damage around the source region. Also, it has been seen that whereas relative sea level in KOS and PLOMARI tide gauge stations are affected by the local tsunami, but relative sea level changes could not be observed in the MENTES station.</p>

Tsunami Fragility — A New Measure to Identify Tsunami Damage —

2009 ◽  
Vol 4 (6) ◽  
pp. 479-488 ◽  
Author(s):  
Shunichi Koshimura ◽  
◽  
Yuichi Namegaya ◽  
Hideaki Yanagisawa ◽  
◽  
...  
Keyword(s):  
Structural Damage ◽  
Field Survey ◽  
Tsunami Inundation ◽  
Fragility Function ◽  
Inundation Depth ◽  
Damage Probability ◽  
Tsunami Damage ◽  
Historical Data Analysis ◽  
Quantitative Manner ◽  
Tsunami Fragility

Tsunami fragility (fragility curve, or fragility function) is a new measure, we propose, for estimating structural damage and fatalities due to tsunami attack, by integrating satellite remote sensing, field survey, numerical modeling, and historical data analysis with geographic information system (GIS). Tsunami fragility is expressed as the structural damage probability or fatality ratio related to hydrodynamic features of tsunami inundation flow, such as inundation depth, current velocity and hydrodynamic force. It expands the capability of estimating potential tsunami damage in a quantitative manner.

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