NH
Natural Hazards

Natural Hazards

Volcanic eruptions: Sometimes natural spectacles, but other times disasters

In April 2018, an eruption of the Kilauea volcano in Hawaii started. The activity continued for months, with impressive lava flows that cut roads and even covered houses and entire neighbourhoods (Figure 1), forcing the evacuation of thousands of people. Fortunately, it did not take any life. Some weeks later, on June 3rd,  Fuego volcano, in Guatemala, shocked the international community with a shorter, but certainly more violent, eruption. The eruption of Fuego volcano, probably less known than Kilauea, affected near two millions of people and sadly caused 190 verified deaths and 238 missing persons.

 

Figure 1. Comparison of satellite images before (left) and after (right) the Kilauea eruption at Leilani Estates subdivision, Hawaii. The area was covered by lava flows. Image credit: USGS.

The main reason why Fuego’s eruption was more deadly than the Kilauea’s one is the type of activity. They are different types of volcanoes with different eruptive dynamics and thus different related hazards. Kilauea is a shield volcano and it is formed by a sequence of eruptions of very low viscous magma. The magma reaches the surface and is generally erupted in an effusive way generating lava flows, really hot mixtures of molten rock, crystals and gas emitted from the volcanic vent, able to reach several meters per second  and kilometers of length, literally looking like rivers (such as in this video). These lava flows can be sometimes accompanied by weak to mild explosive activity in the form of lava fountains. [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]

Mapping population dynamics to advance Disaster Risk Management

Mapping population dynamics to advance Disaster Risk Management

 

Today we have the honour to introduce Sérgio Freire as our guest. Sérgio Freire is a Geographer, currently working as Scientific/Technical Project Manager at the European Commission’s Joint Research Centre (JRC), Directorate E. Space, Security and Migration, Disaster Risk Management Unit, based in Ispra, Italy. His main activities focus on developing applications of the JRC’s Global Human Settlement Layer (GHSL) in the context of disaster exposure, risk, and vulnerability analysis, including modelling population distribution at a range of spatial and temporal resolutions. Current activities also include global mapping and characterisation of human settlements, and developing satellite-based indicators to support monitoring of Sustainable Development Goals.

 

 

  1. When we think about disasters, we firstly mean natural hazards characteristics. However, potential harm comes even from vulnerability and exposure. Can you please explain to us what these elements are and which role they play in the risk equation?

 

In fact, natural hazards are ‘normal’ acts of nature that are part of the living planet that is Earth.

These only make the news and become disasters when they affect people (or property, systems) that display vulnerabilities to those specific phenomena. A strong earthquake in the middle of the Sahara desert may have little or no impacts due to scarce population and settlements, i.e., the absence of exposure. On the other hand, an earthquake of comparable magnitude occurring in cities of dissimilar countries may cause very different impacts and casualties due to the divergent structural vulnerabilities of built-up structures. However, for extreme events or hazards above a certain magnitude, exposure is a major driver of impacts.

Figure 1. Evolution of global population exposed to the highest seismic hazard, by decade. Bars refer to the total population in Modified Mercalli Intensity levels VIII to XII (right axis) and lines refer to percent population change relative to the previous period (left axis) (Source: Freire S., D. Ehrlich, S. Ferri, 2015. Population Exposure and Impacts from Earthquakes: Assessing Spatio-temporal Changes in the XX Century. Computer Modeling in Engineering & Sciences (CMES), SI: ‘Modeling of dangerous phenomena for risk mitigation’. Vol.109(2): 159-182)

 

[Read More]

Bridging the gap between science and decision makers – a new tool for nuclear emergencies affecting food and agriculture

Bridging the gap between science and decision makers – a new tool for nuclear emergencies affecting food and agriculture

The International Atomic Energy Agency (IAEA) has developed an online system to assist in improving the response capabilities of authorities in the event of an emergency caused by natural hazards. This tool provides a clear overview of radioactive contamination of crops and agricultural lands through improved data management and visualization, it also assists in decision support processes by suggesting management actions to decision makers. In this interview, we have the pleasure to introduce Ms Amelia Lee Zhi Yi, working at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture to speak about DSS4NAFA, said system that will be extensively discussed hereafter.

1)  Nuclear Emergency Response (NER) for food and agriculture – why is that important and what does that entail?

In the event of a nuclear or radiological emergency, the response should be performed swiftly in the interest of human health. After ensuring the well-being of the population, it is necessary to prioritize the assessment of possible radioactive contamination of crops and agricultural lands to avoid ingestion of radioactivity.

Proper data management, data visualization and risk communication are essential for efficient response to a nuclear emergency. Factors that should be considered for such response include support for sampling and laboratory analysis, optimal allocation of manpower and analytical instruments, and integrated communication between stakeholders.

To make well-informed decisions on for instance planting and food restrictions, food safety authorities need to have a good understanding of the radiological conditions after a fallout event. This is accomplished through the collection of environmental samples such as soil and plants, and food products that are then analysed using consistent methods in qualified laboratories. Further, these data should be displayed in an intuitive manner so that authorities will be able to interpret the data under stressful, time-bound conditions. Finally, to reduce confusion and clearly communicate decisions made to the public, standardized communication protocols of the decisions made by policymakers need to be implemented. [Read More]