NH
Natural Hazards
Gabriele Amato

Gabriele Amato

My name is Gabriele Amato I am from Rome (Italy) where I studied geology and where I have just finished my PhD, at Roma Tre University. My research is about landslide monitoring through terrestrial and satellite techniques, in different geological and geomorphological contexts. The aim of my PhD was to relate the landslides movement to their triggering factors (rainfall, earthquakes, temperature variations). I am passionate about natural hazards and methods to manage them, especially remote sensing based. In my role as author of the NH blog I am looking forward to sharing course and initiatives organised all around the world in the field of natural hazards with the scientific community, and especially young researchers, since I think these represent great opportunities for networking.

The proliferation of Cyanobacterial blooms: A toxic blue tide

Dr Assaf Sukenik is Senior Scientist at Kinneret Limnological Laboratory of the Israel Oceanographic and Limnological Research. His research interests concern the physiology and biochemistry of freshwater and marine algae, Cyanobacteria and algal toxins, the water quality of freshwater ecosystems.

What are cyanobacteria and what is their natural habitat?

Cyanobacteria (from the Greek word κυανοσ =blue), also known as blue-green algae, constitute the largest, most diverse, and most widely distributed group of photosynthetic oxygenic (oxygen-evolving) prokaryotes[1]. They acquire their energy through photosynthesis, thus are often referred to as algae, although their prokaryotic characteristics (for example, their DNA is not enclosed in a nucleus) differentiate them from eukaryotic[2] algae. The blue-green colour of cyanobacteria is given by their suite of photosynthetic pigments, which differ from that of eukaryotic algae.

Cyanobacteria are also among the oldest organisms on Earth. They appear in fossil records, in sedimentary rocks deposited in shallow seas and lakes 3.5 billion years ago. They played a major role in raising the level of free oxygen in the atmosphere of early Earth and contributed to the evolution of plants. Sometime in the late Proterozoic, or in the early Cambrian, about half a billion years ago, cyanobacteria began to take up residence within certain eukaryotic cells, providing organic compounds for the eukaryotic host via photosynthesis in return for a home in a process known as endosymbiosis[3].

Cyanobacteria are found in a diverse range of habitats, [Read More]

InSAR Norway: the big eye on Norwegian unstable rock slopes

InSAR Norway: the big eye on Norwegian unstable rock slopes

Marie Keiding is a researcher in the Geohazard and Earth Observation team at the Geological Survey of Norway. Together with her colleague, John Dehls, who is leading the project, she works to develop and operate the new mapping service called InSAR Norway.

Before we start, let’s briefly describe what is InSAR. First, the Synthetic Aperture Radar (SAR) is a day and night operational imaging system that can be operated from satellite aircraft or ground and has high capabilities of penetrating clouds because it uses microwaves. Its ‘interferometric configuration’, Interferometric SAR or InSAR, uses two or more SAR images to generate maps of surface deformation or digital elevation models. This is made by calculating differences in the phase of the waves returning to the sensor, as a function of the satellite position and time of acquisition.

Measurements of phase variations are possible only in those pixels of the image where the signal maintains a sufficient coherence between different acquisitions. For this reason, InSAR techniques are particularly suitable to monitor relatively small deformations, in the order of millimetres to centimetres.

Hi Marie, can you tell what is InSAR Norway?

InSAR Norway is the first free and open, nationwide, [Read More]

Landslide forecasting and warning service in Norway

Today our blog will host Graziella Devoli who will tell us about the Landslide Forecasting and Warning Service currently operating in Norway by the Norwegian Water Resources and Energy Directorate (NVE). Graziella is Senior Geologist at NVE and she has PhD in Environmental Geology and Geohazards obtained at the University of Oslo (UiO) where she also teaches in the Geohazards master program. At NVE she works with the organization and development of the national forecasting service and in the daily landslide hazard assessment. Her expertise in this field comes from the years spent working in Nicaragua in natural risk management and emergency planning, where she experienced the importance of adopting multi-disciplinary approaches and strengthening national and international collaboration in disaster risk reduction. Since few years she shares her experience in class organizing a serious game where, using a multi-hazard case study, students analyse roles and responsibility of different stakeholders in disaster preventive actions. The exercise is given to UiO-students and to early career scientists at EGU conference.

Hi Graziella and thank you for being with us. Would you tell us what varsom.no is?

Varsom in Norwegian means “cautious” and Varsom.no is the Norwegian national web portal where daily flood, landslides, snow avalanches warnings and ice conditions on a regional scale are published and represents the main channel to communicate bulletins and warning levels to end-users. [Read More]

Earthquake-induced landslides and the ‘strange’ case of the Hokkaido earthquake

The population of many countries in the world is exposed to earthquakes, one of the most destructive natural hazards. Sometimes, consequent triggered  phenomena can be even worse than the earthquake itself. In this context, earthquake-induced landslides often concur in life and economic losses. To better understand these induced phenomena, updated catalogues of their types and location of occurrence are fundamental. In his works, Dr David K. Keefer performed several interesting statistical analysis, which highlighted how the magnitude and the distance from the epicentre play a key role in triggering earthquake-induced landslides (Figs. 1 and 2). In particular, he showed that the number of landslides induced by earthquakes decreases with the increase in distance from the epicentre (Fig.1) and that the number of landslide increases with larger magnitude events (Fig. 2). [Read More]