Phases Representing Source Lengths of Tsunami in Tide Gauge Records

2007 ◽  
pp. 453-463
Author(s):  
Kuniaki Abe
Keyword(s):  
Tide Gauge ◽  
Tide Gauge Records

scholarly journals Evaluation of ocean circulation models in the computation of the mean dynamic topography for geodetic applications. Case study in the Greek seas

2019 ◽  
Vol 9 (1) ◽  
pp. 154-173
Author(s):  
I. Mintourakis ◽  
G. Panou ◽  
D. Paradissis
Keyword(s):  
Sea Level ◽  
Ocean Circulation ◽  
Tide Gauge ◽  
Dynamic Topography ◽  
Tide Gauge Records ◽  
Mean Dynamic Topography ◽  
Case Study Area ◽  
Extensive Evaluation ◽  
Precise Knowledge

Abstract Precise knowledge of the oceanic Mean Dynamic Topography (MDT) is crucial for a number of geodetic applications, such as vertical datum unification and marine geoid modelling. The lack of gravity surveys over many regions of the Greek seas and the incapacity of the space borne gradiometry/gravity missions to resolve the small and medium wavelengths of the geoid led to the investigation of the oceanographic approach for computing the MDT. We compute two new regional MDT surfaces after averaging, for given epochs, the periodic gridded solutions of the Dynamic Ocean Topography (DOT) provided by two ocean circulation models. These newly developed regional MDT surfaces are compared to three state-of-theart models, which represent the oceanographic, the geodetic and the mixed oceanographic/geodetic approaches in the implementation of the MDT, respectively. Based on these comparisons, we discuss the differences between the three approaches for the case study area and we present some valuable findings regarding the computation of the regional MDT. Furthermore, in order to have an estimate of the precision of the oceanographic approach, we apply extensive evaluation tests on the ability of the two regional ocean circulation models to track the sea level variations by comparing their solutions to tide gauge records and satellite altimetry Sea Level Anomalies (SLA) data. The overall findings support the claim that, for the computation of the MDT surface due to the lack of geodetic data and to limitations of the Global Geopotential Models (GGMs) in the case study area, the oceanographic approach is preferable over the geodetic or the mixed oceano-graphic/geodetic approaches.

scholarly journals Inferring regional vertical crustal velocities from averaged relative sea level trends: A proof of concept

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
H. Bâki Iz ◽  
C. K. Shum ◽  
C. Zhang ◽  
C. Y. Kuo
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Eastern Coast ◽  
Adjustment Process ◽  
Tide Gauge Records ◽  
Relative Sea Level ◽  
Isostatic Adjustment ◽  
Vertical Crustal Motion ◽  
Gps Time Series

AbstractThis study demonstrates that relative sea level trends calculated from long-term tide gauge records can be used to estimate relative vertical crustal velocities in a region with high accuracy. A comparison of the weighted averages of the relative sea level trends estimated at six tide gauge stations in two clusters along the Eastern coast of United States, in Florida and in Maryland, reveals a statistically significant regional vertical crustal motion of Maryland with respect to Florida with a subsidence rate of −1.15±0.15 mm/yr identified predominantly due to the ongoing glacial isostatic adjustment process. The estimate is a consilience value to validate vertical crustal velocities calculated from GPS time series as well as towards constraining predictive GIA models in these regions.

scholarly journals Adaptation time to magnified flood hazards underestimated when derived from tide gauge records

2020 ◽  
Vol 15 (7) ◽  
pp. 074015
Author(s):  
Erwin Lambert ◽  
Jeremy Rohmer ◽  
Gonéri Le Cozannet ◽  
Roderik S W van de Wal
Keyword(s):  
Tide Gauge ◽  
Flood Hazards ◽  
Tide Gauge Records ◽  
Adaptation Time

scholarly journals AERIAL PHOTOGRAPHIC WATERLINE SURVEY OF AN ESTUARY

1974 ◽  
Vol 1 (14) ◽  
pp. 148
Author(s):  
J. SIndern ◽  
G.E. Schroder
Keyword(s):  
Tide Gauge ◽  
High Water ◽  
Aerial Photographs ◽  
Northern Germany ◽  
Tide Gauge Records ◽  
Time Intervals ◽  
Accurate Analysis ◽  
Contour Lines ◽  
Short Time ◽  
Reference Markers

The project of a "barrage across an estuary in Northern Germany was accompanied by a programme to monitor the hydrologic and morphologic situation. This became necessary in order to avoid dangers resulting from the sensitivity of the shallow wadden area to human interference. Various methods to record the morphology were tested. The aerial photographic waterline survey proved superior as it supplies a complete and economic record and allows accurate analysis of the topography. The principle consists in taking aerial photographs at short time intervals between low water and high water, each photo showing a different waterline. The scale chosen was 1:18000, corresponding to a flight altitude of 2700 metres. Rectification of the distorted photos requires reference markers to be distributed over the survey area which measures about 140 km^. By using simultaneous tide gauge records, contour lines can be constructed from the photographed waterlines. This morphologic record is supplemented by submarine survey of the estuary. It is expected that details of sediment transport and of tidal prism changes may be revealed. Predicted and actual effects of the barrage will be compared, which might lead to a better understanding of such coasts.

scholarly journals Synthetically generated low-pressure systems to support studies of sea level extremes

2021 ◽  
Author(s):  
Mika Rantanen ◽  
Jani Särkkä ◽  
Jani Räihä ◽  
Matti Kämäräinen ◽  
Kirsti Jylhä
Keyword(s):  
Sea Level ◽  
Power Plants ◽  
Tide Gauge ◽  
Gaussian Function ◽  
Low Pressure ◽  
Tide Gauge Records ◽  
Pressure System ◽  
Sea Levels ◽  
Input Parameters ◽  
Low Pressure Systems

<p>Extremely high sea levels on the Finnish coast are typically caused by close passages of extratropical cyclones (ETCs), which raise the sea level with their associated extreme winds and lower air pressure. For coastal infrastructure, such as nuclear power plants, it is crucial to study physically possible sea level heights associated with ETCs. Such sea levels are not straightforward to determine from observational datasets only, because tide gauge records  cover about 100 years and do not necessarily capture the most extreme cases having return periods longer than 100 years.</p><p>In this study, a method for generating an ensemble of synthetic low-pressure systems is being developed to investigate the extreme sea level heights on the Finnish coast of Baltic sea. As input parameters for the method, the point of origin, velocity of the center of the cyclone and depth of the pressure anomaly need to be given. Based on the input parameters, the method forms an idealized low-pressure system using a two-dimensional Gaussian function. In order to find extreme, but still reasonable values for the input parameters, cyclone tracks from ERA5 reanalysis data will be analysed.</p><p>The ensemble of synthetic low pressure systems (i.e. the wind and pressure data) is used as an input to a numerical sea level model. As a result, we have an ensemble of simulated sea levels, from which we can determine the properties of the ETCs that induce the highest sea levels on a given location on the coast. The preliminary simulation results show that this method works well, forming a basis for studies on extreme sea levels. </p><p> </p>

Characteristics of the 30 October 2020 Mw 7.0 Aegean Sea earthquake from sea level data analysis and numerical modeling

2021 ◽  
Author(s):  
Mohammad Heidarzadeh ◽  
Ignatius Ryan Pranantyo ◽  
Ryo Okuwaki ◽  
Gozde Guney Dogan ◽  
Ahmet Cevdet Yalciner
Keyword(s):  
Tide Gauge ◽  
Spectral Characteristics ◽  
Maximum Amplitude ◽  
Aegean Sea ◽  
North Coast ◽  
Normal Faulting ◽  
Tide Gauge Records ◽  
The North ◽  
Level Data ◽  
Marine Vessels

<p>The 30 October 2020 tsunami in the Aegean Sea was generated by an Mw 7.0 normal-faulting earthquake at a depth of 21 km. The earthquake epicenter was near the city of Izmir (Turkey) in the Aegean Sea and left 117 fatalities in Turkey and two deaths in Greece. A moderate tsunami was generated, which attacked the nearby coast of Turkey and the north coast of Samos island, Greece.  A maximum runup height of ~3.8 m was observed in Akarca with extensive inundation at the low elevation nearshore areas of the small bays from Akarca (South) to Alacati (North) of the central Aegean coast of Turkey (field surveys by Yalciner et al., 2020). The maximum tsunami penetration was ~2500 m along Azmak streambed at Alacati, Turkey. One casualty and at least one injury were directly attributed to the tsunami in Sigacik, Turkey. The predecessors of this event were other normal-faulting events: i) Lesvos-Karaburun (Mw 6.3) earthquake (Greece-Turkey) on 12 June 2017 approximately 110 km to the North-northwest, and ii) Bodrum-Kos (Mw 6.6) earthquake (Turkey-Greece) on 20 July 2017 approximately 110 km to the south-southeast of the epicenter of the 30 October 2020 event. The events of 2017 and 2020 show high similarities in terms of faulting mechanism and tsunami-genesis. The tsunami generated by the last event caused extensive loss of properties and damage to marine vessels. Here, we study the 30 October 2020 tsunami through analysis of eight tide gauge records as well as numerical simulations. Tide gauge data revealed that the tsunami’s zero-to-crest amplitudes, on tide gauges, was in the range of 5 – 12 cm with maximum amplitude (12 cm) recorded at Kos (Greece). The tsunami duration was unusually long and varied from 20 h to 35 h. Such long tsunami oscillations are not expected from an Mw 7.0 normal-faulting tsunamigenic earthquake and can be most likely attributed to several reflections due to the confined nature of the Aegean Sea region. We conducted Fourier and Wavelet analyses to detect tsunami’s spectral characteristics. Our tsunami simulation was able to reproduce most features of the recorded waves both in terms of amplitudes and duration. This research is suported by Royal Society (UK), grant number CHL/R1/180173. </p>

scholarly journals Sinking Tide Gauge Revealed by Space-borne InSAR: Implications for Sea Level Acceleration at Pohang, South Korea

2019 ◽  
Vol 11 (3) ◽  
pp. 277 ◽  
Author(s):  
Suresh Palanisamy Vadivel ◽  
Duk-jin Kim ◽  
Jungkyo Jung ◽  
Yang-Ki Cho ◽  
Ki-Jong Han ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
Tide Gauges ◽  
Tide Gauge Records ◽  
Relative Sea Level ◽  
Tide Gauge Station ◽  
Sea Level Acceleration ◽  
Vertical Land Motion ◽  
Gauge Station

Vertical land motion at tide gauges influences sea level rise acceleration; this must be addressed for interpreting reliable sea level projections. In recent years, tide gauge records for the Eastern coast of Korea have revealed rapid increases in sea level rise compared with the global mean. Pohang Tide Gauge Station has shown a +3.1 cm/year sea level rise since 2013. This study aims to estimate the vertical land motion that influences relative sea level rise observations at Pohang by applying a multi-track Persistent Scatter Interferometric Synthetic Aperture Radar (PS-InSAR) time-series analysis to Sentinel-1 SAR data acquired during 2015–2017. The results, which were obtained at a high spatial resolution (10 m), indicate vertical ground motion of −2.55 cm/year at the Pohang Tide Gauge Station; this was validated by data from a collocated global positioning system (GPS) station. The subtraction of InSAR-derived subsidence rates from sea level rise at the Pohang Tide Gauge Station is 6 mm/year; thus, vertical land motion significantly dominates the sea level acceleration. Natural hazards related to the sea level rise are primarily assessed by relative sea level changes obtained from tide gauges; therefore, tide gauge records should be reviewed for rapid vertical land motion along the vulnerable coastal areas.

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