|CIESM International Conference on East - West Cooperation in Marine Science
(Sochi, 1-3 December 2014)
Abstracts of Panel communications
Panel [A] - Physical processes in coastal waters
Panel [B] - Geo-hazards
Panel [C] - Invasive species
Panel [D] - Contaminants & marine litter
Panel [E] - Marine biotechnology & society
Panel [F] - Data harmonization
Panel [B] - Geo-hazards
co-moderators : Drs Eugene Kulikov and Jean Mascle
Title : Monster waves in Russian Waters
by Ira Didenkulova
Nizhny Novgorod State Technical Univ. n.a. R.E. Alekseev, Russia
The ever growing use of coastal territories requires taking into account risks related to marine hazards. While storm related hazards, which are in the responsibility of hydrometeorological service and the Russian Ministry for Emergency Situations, are monitored, the situations related to tsunamis in Russian internal waters and rogue waves and caused by them flash floods are not considered. The recent history of such events occurred in Russian waters is re-examined. The mechanisms of rogue wave formation and their risks for Russian coastal waters are studied. The tsunami risk for Russian internal seas (Black, Caspian and Baltic Seas) and waters (water reservoirs, rivers and lakes) is discussed.
Title : Numerical modeling of the extreme bora events over Black and Mediterranean Seas
by Alexander Gavrikov
P.P. Shirshov Inst. of oceanology, Moscow, Russia
Realistic numerical simulation of the extreme bora events is highly important for understanding mechanisms driving the bora dynamics and forecasting of associated weather extremes. Weather Research and Forecasting (WRF) nonhydrostatic numerical model was used to simulate the bora event in January - February 2012 over the northeastern coast of the Black Sea. This was the most intense bora since 1997 in the Black Sea. Observed wind speed during the event has exceeded 30 m/s with the gusts of up to 45 m/s. Simulations were performed using nested grids with spatial resolution for the outer domain being 9 km and for the interim and inner domains 3 and 1 km respectively. Results of the simulations have been validated against instrumental measurements at the coastal stations. We were capable of simulating realistic bora features, including also response of off-shore winds to the local topography that was well compared to the co-located satellite observations.
Title : Wind Wave Modeling in extreme storms of the Black Sea
by Ilia Kabatchenko, Vvedenskiy A.R., Litvinenko G.I., Fomin V.V.
State oceanographic institute, Moscow, Russia
Black sea is one of “quietest” among the seas surrounding Russia. The average wind wave energy in comparison with the majority of the seas of Russia is insignificant. In spite of it, there are messages about exceptional destructions of the engineering constructions caused by storms at its coast and about the ships which sank on its water area from time to time. Such tragedy occurred on Black sea in the fall 1854 during, so-called « Balaclava storm » when the all of the thirty four ships of the English NAVY sank.
Such events continue to occur now. There are three storms that had the greatest destructions in the northwest of the Black sea last years. The storm which took place at coast of Crimea on November, 9th, 1981 when the gas platform was destroyed and the new breakwater which had been just built in the Sevastopol bay was damaged. The storm on November, 11th, 2007 in the Strait of Kerch during which 10 ships were damaged and four of them sank. And the storm which was in the area of the Big Sochi on December, 13th, 2009 that led to destruction of the cargo port in area of the Mzimta creek.
Using the modern model of wind wave in all of these storms helped to calculate the wave field and to identify the reasons.
Title : Seismic hazard assessment of the offshore section of South Stream gas pipeline route across the Black Sea
by Leopold I. Lobkovsky, Alexey I. Ivaschenko*, Sergey A. Kovachev
P.P. Shirshov Inst. of oceanology, Moscow, Russia
For seismic hazard assessment of the offshore section of South Stream gas pipeline route across the Black Sea some stages were executed:
• The review of seismotectonic data for the Black Sea region including prior studies and available earthquake catalogs.
• The analysis of the microearthquake records of the short-term OBS observation at the Black Sea bottom along pipeline route.
• The performing PSHA (Probabilistic Seismic Hazard Assessment) for selected sites along the pipeline route including:
1. the development of the source zone and magnitude-frequency models,
2. the selection of appropriate ground motion attenuation models,
3. the development of the logic-tree model to account for uncertainties,
4. the calculation of design PGA, PGV, and uniform 5%-damped RSA for selected sites assuming uniform soil profile (basement) and for return periods 100, 200, 500, 1000, 2000, 5000, 10000 yrs.
• The disaggregation of the PSHA results and determination of magnitudes and distances dominating the long-period and short-period hazard for selected sites and return periods of interest.
• The generation of appropriate time histories of acceleration consistent with PSHA and disaggregation results for selected sites.
The earthquake catalog of historical earthquakes includes 2906 events (update as Dec 1, 2011) was compiled, but only 1429 events (~ 50%) were of moment magnitude Mw > 5, i.e. of engineer interest. We excluded 925 remote events of moment magnitude Mw < 7.5 occurred in Turkey as they can’t affect the pipeline, and remain only 17 events of moment magnitude Mw > 7.5 from Turkey as they can dominate long-period hazard for pipeline. Following the same reasoning we excluded 307 events occurred in the Carpathian region and remained only 3 events with Mw > 7.5, and, finally, excluded all 45 events occurred in the Main Caucasus region because no events with Mw > 7.5 is known for that area. The remaining 152 events (~ 5% of total catalog) characterize seismic activity within the pipeline route corridor ±250 km in width. The catalog seems to be complete for the last 100 years, except the Central Basin, for which the completeness interval is ~ 80 yrs.
Based on historical data, seismic activity along the planned South Stream pipeline routes appears to be low to moderate except for the ANAPA landfall area and VARNA landfall area. Probabilistic Seismic Hazard Assessment (PSHA) for the planned South Stream pipeline route has been performed. 206 sites were evenly spaced along the pipeline routes with a step of about 7 km on average.
PSHA results: For the return period T = 1000 years:
Peak Ground Acceleration (PGA) changes along the pipeline route from 0.33 g at the ANAPA landfall to about 0.10 g within the Central Basin, and to 0.28 g at the VARNA landfall.
In the Central Basin PGA is about 0.22 g near the suspected existence of active faults in this area, otherwise PGA would be about 0.10 g. The presence of active faults needs to be confirmed by further investigations.
The long-period hazard at the VARNA region is slightly dominated by large earthquakes that occur in Vrancea and Turkey regions. However, the short-period hazard is completely due to local earthquakes as it follows from disaggregation of the PSHA results.
Calculated PGA, PGV, and 5%-damped RSA as well as generated time histories for characteristic points and different return periods are recommended for design.
Title : Marine Geo-Hazards in and around the Mediterranean Sea
by Jean Mascle
Observatoire Océanologique de Villefranche sur Mer, France
What are the main catastrophic geo-hazards that could affect the Mediterranean Sea coasts? They are the same as elsewhere: earthquakes, volcanic eruptions submarine slides and, one or their consequences, tsunamis. One of the specificities of the Mediterranean is that these events occur in a narrow domain where almost 500 millions people are living, including 160 millions directly on the seashore, and visited each year by more than 300 millions tourists! So the Mediterranean Sea, the cradle of the Western civilization, is particularly sensitive to natural geo-hazards. Since historical times, we know that geo-hazards have always played a major role in the evolution of human societies around the Mediterranean Sea (Santorini, Pompei, Alexandria, Messina, etc,). Similar catastrophic, and less damaging, events may today still occur in and around the Mediterranean Sea and still remain difficult to be predicted!
Most of the catastrophic geo-hazards occurring in the Mediterranean Sea are consequences of its specific plate tectonic configuration, inherited from a long-term geological evolution (more than 200 Ma). Today the Mediterranean Sea is made of two main basins of different ages (more than 150 Ma and less than 30 Ma respectively) almost totally surrounded by mountain chains resulting from subduction and collision of former oceanic spaces and of their continental margins. A direct consequence of this setting is an intense, widely but not equally, distributed, seismicity activity. A cloud of seisms, including some with magnitude higher than 7, is superposed to the Anatolian and Aegean regions; this activity results from three parameters (1) the subduction of the African plate beneath Eurasia, (2) the lateral escape (with respect to Europe) of the Anatolian micro-plate and (3) the stretching of the Aegean continental crust. Westwards the Aegean seismic nest connects with a less active seismic belt passing through the various Alpine mountain chains, and the Apennines. Another intensively active seismic zone can be seen over southern Italy; its underlines the subduction of the African lithosphere beneath Europe, particularly beneath the Tyrrhenian Sea, and connects through Sicily with a another belt of earthquakes superposed to the North African coastal chains and the Atlas mountains. To the west the Iberian micro-plate is surrounded by moderate seismic activity, which connects progressively with the Mid Atlantic Ridge. Another consequence of plate convergence is the presence of active, or historically active, chiefly explosive, volcanoes delineating the Aegean volcanic arc and the Aeolian Islands. Two others volcanic domains, not directly related but interfering with subduction processes, are particularly active nearby the area: the Vesuvius and the Phlegraean fields nearby Napoli and Mount Etna in North-Eastern Sicily.
All systems represent permanent risks, which have to be continuously monitored. Submarine earthquakes, volcanic activities and submarine slides may moreover generate tsunamis, which are among the most frequent catastrophic events but have been until recently often neglected since their geological records remain difficult to assess. Submarine earthquakes trigger most of the major tsunamis whose resulting waves are crossing regional basins before to hit the opposite, northern or southern, coasts tens of minutes later. More local tsunamis may be generated as consequence of submarine sedimentary, or volcanic, failures; such events may quickly (few minutes later) impact the neighboring coasts where they may also induce important damages. Most of the continental slope of the Mediterranean continental margins being either quite steep, or highly sedimented, may be submitted to large-scale destabilizations and therefore may be considered as areas to be surveyed for slope stability. Catastrophic (instantaneous) geo-hazards are the most spectacular and as such remain in the historical memory and are even sometimes at the origin of myths. Others natural, but slower, geological events have however to be considered when trying to evaluate the various marine-related risks occurring in the Mediterranean Sea; the most obvious of them relates to the sea level fluctuations and particularly to sea level progressive rise, itself related to climatic fluctuations.
Title : From Tsunami Early Detection and Warning to Multi Hazards Early Detection and Warning
by Sergiu Dov Rosen
In November 2005, following the terrible the Indian Ocean tsunami event, the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and connected seas (ICG/NEAMTWS) was established by an Intergovernmental Coordination Group (delegates of IOC/UNESCO member states). It was established because the Mediterranean region ranks second in the world, in the number of tsunami events which occurred in the last ~3000 years. The tsunami majority (~88%) are generated by earthquakes (~75% by direct tectonic plate movements; ~8% by earthquakes induced submarine landslides; ~5% by volcanic eruptions). Of the remaining 12%, 2% are meteo-tsunamis and 10% of unknown source. Detection of an earthquake magnitude and its epicentre location takes nowadays a few minutes and a few more are needed to estimate its hypocentre below sea bottom. If the hypocentre depth is smaller than 100km, the earthquake has tsunamigenic potential. Not all strong shallow earthquakes generate tsunamis, hence confirmation of tsunami generation is necessary. Detection is done by monitoring sea surface fluctuation at sea level stations and/or by sea bottom located pressure sensors.
The MedGLOSS sea level monitoring network established jointly by CIESM and IOC/UNESCO, with many stations donated by CIESM (two in the Black Sea), has been used as one of the founding bricks of the NEAMTWS real time (RT) sea level monitoring system. Presently, the NEAMTWS sea level stations transfer RT data (requested update every 1’, yet not all complying) to the IOC Sea Level Data Facility, and displayed “AS IS” on the Internet, with no quality control. The NEAMTWS present state loses time waiting for tsunami confirmation before its dissemination. Furthermore, in an earthquake induced landslide on the continental shelf, the existing system is unable to detect a landslide or tsunami generated by it. Moreover, if the seismic waves of a strong earthquake with the hypocentre > 100km, reach a shelf with fine unconsolidated sediments (e.g. off Nile delta), they may become strong enough to trigger landslide induced tsunami. A relatively new early tsunami detection method, based on high frequency multi antenna radar system was developed and proven effective (WERA HF Radar). It is able to detect and monitor tsunami of any type (at about -100m depth contour) with a detection delay of 3’. Furthermore, it is able to simultaneously monitor the waves (directional wave spectrum) and the surface currents, up to about 200km from the coast, as well as the wind directions over the area covered between any two neighbouring stations and the offshore 200 km boundary.
Since tsunamis are relatively infrequent events, although of high damage potential, a hybrid multi hazard early warning system, based on HF Radar stations, combined with RT national sea level monitoring stations providing RT quality controlled sea level data, would constitute a significant enhancement to existing NEAMTWS. It would improve early detection and warning reliability, from a multitude of marine hazards including all tsunami types, storm surge (and meteo-tsunamis), wind and wave storm events and floods induced by reduction of the flow gradients due to high levels at river mouths. In addition, the costs of maintenance and operation would be reduced and more justifiable.
For this, cooperation in provision of RT sea level data from Russian stations in the Black sea and for establishing a multi hazard early warning system in the Mediterranean and Black sea is necessary.
Title : Active Geology and Marine Geo-Hazards at the Black Sea Outflow: The Aegean Region
by Dimitris Sakellariou
HCMR, Athens, Greece
The Aegean Region (Hellenic Arc and Back-Arc, Aegean and Ionian Seas) has been for several million years and continues to be the site of long-term crustal movements, deformation and geodynamic processes, which frequently give birth to violent, short-term, catastrophic, geological events, called hereafter geo-hazards. Large earthquakes, seafloor ruptures, uplift or subsidence of shorelines, earthquake triggered or aseismically developed submarine landslides, major or minor submarine or island volcanic eruptions occur within the various tectonic settings of the Aegean and Ionian Seas. Some of these marine geological processes in the near past have triggered small or large tsunamis, some of which were disastrous for the Aegean, Ionian or even Eastern Mediterranean coastal region.
Information on the effects of the past disasters are very diffuse, especially if they took place in earlier times, and the reliability of the available tsunami catalogs has been questioned and reexamined. But even so, similar processes are expected to and will occur in the near or far future. If we consider that the coastline of Eastern Mediterranean Sea is much denser populated than it was in the past, it is easy to imagine the tremendous disaster they can cause.
It is thus of great importance that scientists from all different disciplines, like marine geologists, seismologists, modelers, engineers etc, join forces, resources and efforts in order to better understand triggering mechanisms and occurence of marine geo-hazards.
Title : Geohazard evaluation based on GIS and remote sensing in the context of cliff/bluff erosion vulnerability along the Bulgarian coast
by Margarita Stancheva, Robert Young and Hristo Stanchev
Bulgarian Academy of Sciences, Varna, Bulgaria
The continuing increase in coastal population requires adequate and reliable information for the assessment of various geohazards associated with coastal erosion, landslides, wave attacks, floods and tsunami. In Bulgaria major hazards related to geological structure of the coast and subsequent processes are cliff erosion, coastal landslides and flooding of low-laying territories due to extreme sea level rise. Coastal erosion and landslide phenomena generate significant economic, social and environmental costs. Currently, coastal erosion is a widespread process along the 412 km long Bulgarian Black Sea coastline, as 60 % of it comprises an eroding cliff. In order to find the most relevant solution to control coastal erosion, it is important to determine its reasoning. Different factors contribute to increase of erosion and landslides along the Bulgarian coast: 1) environmental factors, like geological settings of the coast, shortage in sediment supply, sea level rise and more frequent storm surges, etc.; and 2) factors related to human activities, such as coastal urbanization, expanded developments and armouring coastline by hard engineering structures (dikes, seawalls and solid groins).
High Resolution (HR) orthophotos, along with solid geological data, can be integrated within a GIS database to produce maps of coastal vulnerability with good accuracy. This information will help to guide development planning in coastal areas that might potentially be subject to erosion, storm surge flooding and other coastal hazards both at the present time, and increasingly in the future in response to projected sea level rise.
A modern, geomorphic GIS-based classification of the Bulgarian coast has been developed to provide the basis for identifying and evaluating those areas most prone to various coastal hazards. Several types of data were used: HR orthophotos, topographical maps in 1:5,000 scale and geological maps. Geomorphic classification utilized both geomorphological and engineering criteria. A total of 867 segments were delineated along the coast. 465 were classified as natural landforms (cliffs, beaches, river mouths) with a total length of 362,62 km and 402 were indicated as technogenous segments (port and coast-protection structures, artificial beaches) with a total length of 70 km. Based on the geologic materials present at each segment and cliff height, the cliffed portions of the Bulgarian coast were classified for expected erosion rates, and therefore, hazard vulnerability: low hazard (volcanic type cliff); moderate hazard (limestone type cliff) and high hazard (loess and clayey types cliff). This “predictive model” was then compared to a previously published field study of coastal erosion rates to validate the model. As a result, a new high quality, but qualitative data for Bulgarian coastal bluff/cliff erosion were obtained, incorporated and analysed in GIS. As the erosion rate and vulnerability of the coastline is constantly changing due to natural and anthropogenic factors, the erosion sensitivity map supported by HR digital orthophotos and GIS methods is very useful in identifying cliff locations along the Bulgarian coast that may be most susceptible to erosion. These areas, especially when coincide with densely populated areas, should be closely monitored.
Title : A silent hazard: Widespread occurrence of tsunami-like waves in the Mediterranean and Black Seas generated by high-altitude atmospheric forcing
by Ivica Vilibic, Jadranka Sepic, Alexander B. Rabinovich, Sebastian Monserrat
Institute of Oceanography and Fisheries, Split, Croatia
Meteorological tsunamis (“meteotsunamis”), also known as "rissaga" (Balearic Islands), "sciga" (Adriatic Sea), and "marrubbio" (Sicily), are destructive tsunami-like waves generated by atmospheric disturbances (atmospheric waves, pressure jumps, frontal passages, squalls). Strong meteotsunamis are usually not associated with extreme atmospheric events, such as hurricanes or major storms, but with marginally detectable changes in atmospheric pressure (often caused by atmospheric gravity waves) that frequently take place during times of calm and pleasant weather; their formation is related to very specific and comparatively rare resonant situations that lead to strong amplification of the initial waves. A series of meteotsunamis with height of up to 3 metres struck several southern European countries during the period 23 to 27 June 2014, causing considerable damage and distress from Spain to the Ukraine. Coastal observations reveal that the wave events coincided with a period of calm surface weather but very strong upper tropospheric winds embedded in dynamically unstable atmospheric layers that were propagating eastward across the Mediterranean. This unique synoptic weather pattern favoured generation and propagation of a great number of atmospheric disturbances over much of the Mediterranean, providing a clear and quantifiable link between the synoptic pattern, surface air pressure disturbances and the destructive tsunami waves. This is the first documented case of a chain of destructive meteorological tsunamis occurring over a distance of thousands of kilometres, as meteotsunamis are normally localised to a basin not larger than a few hundreds of kilometres. The June 2014 event is the only Mediterranean-wide destructive event observed in the last half-century, a period for which tide gauge measurements and eyewitness reports are available. This suggests either a long return period for such events or a link to climate change. Either way, it is clear that the threat from meteotsunamis should be incorporated within future tsunami warning systems.