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earthquake

A better framework for disasters

A better framework for disasters

The end of the Northern hemisphere summer tends to be a good time to regroup from natural hazards, as the frequency and intensity of storms, as well as the incidence of wildfires, tends to trail off. At the time of writing, however, Hurricane Willa had just crashed into Mexico, while Typhoon Yutu has just hit the Northern Mariana Islands so hard that any equipment designed to record wind-speed had been swept away. Both storms rapidly strengthened, and the latter was described by the US National Weather Service as ‘likely [to] become the new yard stick by which future storms will be judged.’

Super Typhoon Yutu (24 October 2018) making its way towards the Northern Mariana Islands, a territory of the United States. (Photo: Joshua Stevens/NASA Earth Observatory)

What if we changed the way we think about such events, though? What if, instead of focusing on the wind-speed of a typhoon or the magnitude of an earthquake, the first points of discussion were about the human aspect and impact associated with a specific event. How would this summer’s events be framed? It’s a crucial distinction; natural disaster is in some ways a paradox in terms – although the hazard, or physical manifestation, of a hurricane or earthquake is natural, the impacts, and thus the disaster, are entirely a result of human exposure and vulnerability. Let’s first explore some of the most dramatic themes from this summer’s disasters, and then try and put them in this new human context.

What links this summer’s events?

The recent Hurricanes – Yutu, Willa, Florence and Michael – encapsulate well the intensity and frequency at which we’ve seen disasters come over the last few months. Earthquakes, storms, droughts and wildfires have all caused havoc in a hugely diverse spectrum of locations, and while the specter of natural hazards is always present in many parts of the world, there seems to be something more intense and urgent with respect to this summer’s catastrophes, especially in the media coverage.

The availability of smartphones and the proliferation of social media use means we can see ever more easily from the safety of our homes what others experience in terror during disasters; who could forget the scarring imagery from the earthquake and tsunami in Lombok in September, as houses were tossed about like toys as the ground turned to liquid.

Elsewhere, Japan experienced a plethora of hazards as flooding, typhoons, landslides, earthquakes and drought brought a whole range of challenging conditions which caused a large number of fatalities, despite Japan’s status as one of the best prepared countries in the world for natural hazards.

Much of the media discussion related to disasters has focused on the links between hazards and climate change, and whether the severity of events like Hurricane Florence can be attributed in part to anthropogenic emissions. While it has historically proven difficult to attribute the strength of different storms to climate change, this summer marked the first time scientists attempted it in earnest while an event was taking place – some researchers argued that the rainfall forecast for Hurricane Florence was 50% higher than it would otherwise have been, although such estimates are still in their infancy. What is clearer from scientific predictions of future climate change is that storms will likely be stronger, wetter and slower moving, suggesting similar intense storms could become more normal.

Beyond tropical storms, records were broken by other catastrophes. The Northern hemisphere wildfire season was among the worst we’ve ever experienced on record, at least in terms of acreage burned. Californian fires were so intense that smoke was noticeable on the East Coast, while the extent of fire in western Canada was second only to the cataclysmic fires last year. Abnormally warm temperatures in Scandinavia prompted wildfires to break out north of the Arctic circle, an extremely rare and concerning occurrence.

A different way to think about catastrophes

While it’s interesting and important to discuss the potential for increased storm severity as a result of climate change, it seems that this should only form a part of the larger discussion: how will trends in climate co-evolve with trends in human exposure and vulnerability to hazards? Similarly, why focus on the numbers associated with a disaster – the earthquake magnitude, the depth of flooding, acres of forest burned – when we could instead look at who has been impacted, and how to prevent this in the future.

It’s especially important to frame the ‘cost’ of a given event in this context. Often, we think of cost in either loss-of-life or financial terms, but it’s worth considering those as functions of exposure and vulnerability. For example, Hurricane Florence, which recently made landfall on the US eastern seaboard, is likely to cost  40-50 billion US dollars. Compare this to Hurricane Maria, which devastated Puerto Rico in 2017; some estimates for the cost of the storm were around 100 billion US dollars. While Hurricane Maria cost roughly twice as much as Florence, the relative impact on Puerto Rico was far greater than that value would imply. The vulnerability of the economy of Puerto Rico to a disaster of that scale was far higher than the mainland US; with a GDP of over 10 trillion US dollars, the US economy can absorb shocks like Florence, but the GDP of Puerto Rico declined by a massive 8% in the aftermath of Maria. It is worth noting that Puerto Rico is in fact a territory of the US, and received federal funding to assist with recovery – so the economic impact might even have been more severe without it.

U.S. Customs & Border Protection & FEMA personnel deliver food and water to isolated Puerto Rico residents after their bridge was destroyed by Hurricane Maria in the mountains around Utuado, Puerto Rico (Photo: U.S. Air Force/Master Sgt. Joshua L. DeMotts via FEMA)

We can build the same framing for loss of lives; countries with well-developed disaster response and recovery mechanisms suffer significantly fewer fatalities in the face of a similar magnitude event to a poorly equipped country, all things being equal. This kind of social vulnerability to disaster is difficult to quantify, and encompasses a range of aspects including cultural awareness of natural hazards and healthcare expenditure, but it has to be considered alongside the trends in hazard intensity.

I would argue that coverage of (and research related to) disasters needs to shift away from the headline numbers, like skyrocketing costs or the increasing intensity of storms and wildfires, and instead discuss whether disasters are hitting harder in places that are more vulnerable, or whether the relative economic or human exposure to a given type of disaster is worsening or not. While it’s fascinating to see images of multiple hurricanes over a single basin, it’s an incomplete picture unless the risk is incorporated.

Flash flood impacts in Peru after torrential rain in 2013 (Photo: Galeria del Ministerio de Defensa del Perú via Flickr)

Reframing our vision of disasters would put the focus squarely on where inequality and climate change interact; if more vulnerable developing countries or regions are expected to be more exposed to disasters under a changing climate, then there is real potential for inequalities to be exacerbated – and this is indeed what the UN anticipates will occur. More fundamentally, reframing would help us shift away from a coldly analytical perspective of ‘disasters by the numbers’ and instead consider where the worst impacts would be, and who the people at risk are. While trends in the developed world indicate fewer and fewer deaths from disasters over the last 100 years, many countries don’t have the same capacity to absorb shocks.

The human tendency to dwell on the extraordinary, and the ephemeral nature of modern news coverage certainly encourages reporting to focus on the records broken by a given event. Perhaps it’s futile to add another voice to the many that have already asked for more context and temperance from such coverage, but it seems important to highlight that there may be other ways to cover disasters; those affected may benefit greatly, in both the long and short term.

Robert Emberson is a Postdoctoral Fellow at NASA Goddard Space Flight Center, and a science writer when possible. He can be contacted either on Twitter (@RobertEmberson) or via his website (https://robertemberson.com/)

Editor’s note: This is a guest blog post that expresses the opinion of its author, whose views may differ from those of the European Geosciences Union. We hope the post can serve to generate discussion and a civilised debate amongst our readers.

September GeoRoundUp: the best of the Earth sciences from around the web

September GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, major geoscience headlines, as well as unique and quirky research, this monthly column aims to bring you the latest Earth and planetary science news from around the web.

Major stories

This month has been a whirlwind of Earth and space science news; the majority focusing on natural hazards. Powerful cyclones, earthquakes, and tsunamis have received significant coverage from the geoscience media. Quickly recap on an action-packed month with our overview:

On 14 September, Hurricane Florence, made landfall in the mid-Atlantic region of the United States, making first contact near Wrightsville Beach in North Carolina then traveling up the East Coast. By the time Florence had reached the US coastline, the cyclone’s sustained wind speed had dropped considerably, downgrading the hurricane from a category 4 to category 1 storm on the Saffir–Simpson scale.

This designation may sound mild, but as many scientists and journalists have pointed out, sluggish hurricanes are especially dangerous, since they are more likely to dump heavy rainfall over a relatively small surface area compared to faster storms that distribute their rainfall over more territory. This proved to be true for Hurricane Harvey, which dumped more than 150 centimetres of rain onto some areas of Houston, Texas.

Hurricane Florence’s record-breaking rainfall forced more than a million people to evacuate their homes, and experts estimate that the storm inflicted damages worth more than $38 billion (USD). The hurricane also produced very concerning environmental damages. In Wilmington, North Carolina, for instance, the the rainfall flooded a pit of coal ash at a power plant, releasing more than 1,530 cubic metres of ash, with much of it likely ending up in a nearby lake.

Across the planet, just one day following Hurricane Florence’s landfall, Super Typhoon Mangkhut wreaked havoc on southeast Asia, pounding the Mariana Islands, the Philippines, China, Taiwan, and Vietnam with strong wind and rain. Reaching wind speed over 240 kilometres per hour, Mangkhut is the most intense storm of the year so far. The New York Times created an interesting three-dimensional visual of the storm’s intensity, using NASA satellite data.

In addition to unleashing incredibly strong winds, the typhoon’s rainfall also triggered deadly landslides. Just outside of the city Baguio, which recorded more than 75 centimetres of rain, more than 40 gold miners were buried under a landslide that hit their bunkhouse.

Big storms like Hurricane Florence and Typhoon Mangkhut are expected to be more frequent in the future as our climate changes. And this stems from many factors; a recent article from the New York Times explains that, due to climate change, the world’s oceans are warming (fueling more hurricane formation), the atmosphere is holding more moisture (leading to wetter storms), hurricane wind speeds are slowing down (causing more concentrated rainfall), and Earth’s sea levels are rising (increasing the risk of flooding).

Last week, a 7.5-magnitude earthquake struck the Indonesian island of Sulawesi, sending a massive tsunami, with waves up to 6 metres high, into Palu Bay, causing massive devastation in the regional capital Palu and surrounding areas. Officials report that nearly 1,350 people have died from the earthquake and tsunami, and the death toll is expected to rise as rescue workers make their way towards more remote places. Scientists told BBC that “a combination of geography, timing and inadequate warnings meant that what happened in Palu was a worst case scenario.”

Map of the September 28, 2018 Palu, Indonesia Earthquake. Credit: USGS.

Indonesian aid workers and humanitarian relief envoys are currently working to provide supplies and assistance to the affected communities. At the same time, scientists are still puzzling over the tsunami’s strength, which caught many experts by surprise. This is because the earthquake’s behavior isn’t known for generating catastrophic tsunamis.

Powerful tsunamis are typically caused by earthquakes with vertical motion, where part of the seafloor juts forward, disturbing the water column and consequently sending massive waves to the coast. The 2004 Indian Ocean tsunami, for example, was caused by a 9.1 magnitude megathrust earthquake. On the other hand, last week’s quake is known as a ‘strike-slip earthquake,’ where the ground shifts horizontally. This kind of movement doesn’t move ocean water as dramatically.

“Some early calculations suggest a floor displacement of perhaps half a metre. Significant but generally insufficient to produce the waves that were recorded,” reported the BBC.

While it is too early to tell what exactly happened, scientists suspect that a number of factors could have played part in helping the tsunami gather strength. For example, underwater landslides have been known to trigger tsunamis of similar strength. Additionally Palu Bay’s narrow geometry could have amplified the waves’ height.

The underlying factors that contributed to the event will hopefully become more clear as scientists analyse the series of events in more detail.

What you might have missed

This month, the Japanase spacecraft Hayabusa 2 has sent three robots to the rocky surface of an asteroid near Earth, known as Ryugu. The spacecraft had successfully reached the asteroid this June, after travelling for more than three years. The craft first released two small devices, no bigger than frying pans, which tumbled around the rock’s surface and even sent digital postcards and a short video back home. A few days ago, Hayabusa 2 released a third rover, which will use a suite of different scientific instruments to collect data on the asteroid. “Hayabusa2 itself is likely to make the first of three touchdowns on the asteroid to collect samples later this month,” said Science Magazine.

Links we liked

  • StarTrek creators once said that Spock’s fictional home planet Vulcan orbited the 40 Eridani A star. Now scientists have found an exoplanet that fits the description.
  • Rediscovered: the 19th century geological drawings of Orra White Hitchcock, a pioneering female scientific illustrator
  • Researchers discover that kidney stones grow and dissolve much like geological crystals
  • We all know about lava volcanoes, but have you heard of ice volcanoes? New study suggests that cryovolcanoes have likely been erupting for billions of years on Ceres.
  • This new map of Antarctica is like ‘putting on glasses for the first time and seeing 20/20’

The EGU story

Last week, the EGU hosted its first science-policy dinner debate in Brussels. The event, ‘Horizon Geoscience: overcoming societal challenges, creating change’, was organised in collaboration with the European Federation of Geologists (EFG) and brought together geoscientists, policymakers and industry representatives. On the EGU website, we report on the outcome of the discussion and publish the key findings from the Horizon 2020 Geoscience Survey conducted earlier this year.

Panel members during the Horizon Geoscience dinner debate. From Left to right: Jonathan Bamber, John Ludden Lieve Weirinck, Jean-Eric Paquet and Vitor Correia

In the past few weeks, we have also issued three press releases highlighting research published in some of EGU’s open access journals. Follow the links to find out how bombing raids in the Second World War impacted the ionosphere, how glacial geoengineering could help limit sea-level rise, and what the point of no return for climate action might be.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

Geosciences Column: Extreme snowfall potentially worsened Nepal’s 2015 earthquake-triggered avalanche

Geosciences Column: Extreme snowfall potentially worsened Nepal’s 2015 earthquake-triggered avalanche

Three years ago, an earthquake-induced avalanche and rockfalls buried an entire Nepalese village in ice, stone, and snow. Researchers now think the region’s heavy snowfall from the preceding winter may have intensified the avalanche’s disastrous effect.

The Langtang village, just 70 kilometres from Nepal’s capital Kathmandu, is nestled within a valley under the shadow of the Himalayas. The town was popular amongst trekking tourists, as the surrounding mountains offer breathtaking hiking opportunities.

But in April 2015, a 7.8-magnitude earthquake, also known as the Gorkha earthquake, triggered a massive avalanche and landslides, engulfing the village in debris.

Scientists estimate that the force of the avalanche was half as powerful the Hiroshima atomic bomb. The blast of air generated from the avalanche rushed through the site at more than 300 kilometres per hour, blowing down buildings and uprooting forests.

By the time the debris and wind had settled, only one village structure was left standing. The disaster claimed the lives of 350 people, with more than 100 bodies never located.

Before-and-after photographs of Nepal’s Langtang Valley showing the near-complete destruction of Langtang village. Photos from 2012 (pre-quake) and 2015 (post-quake) by David Breashears/GlacierWorks. Distributed via NASA Goddard on Flickr.

Since then, scientists have been trying to reconstruct the disaster’s timeline and determine what factors contributed to the village’s tragic demise.

Recently, researchers discovered that the region’s unusually heavy winter snowfall could have amplified the avalanche’s devastation. The research team, made up of scientists from Japan, Nepal, the Netherlands, Canada and the US, published their findings last year in the EGU’s open access journal Natural Hazards and Earth System Sciences.

To reach their conclusions, the team drew from various observational sources. For example, the researchers created three-dimensional models and orthomosaic maps, showing the region both before it was hit by the coseismic events and afterwards. The models and maps were pieced together using data collected before the earthquake and aerial images of the affected area taken by helicopter and drones in the months following the avalanche.

They also interviewed 20 villagers local to the Langtang valley, questioning each person on where he or she was during the earthquake and how much time had passed between the earthquake and the first avalanche event. In addition, the researchers asked the village residents to describe the ice, snow and rock that blanketed Langtang, including details on the colour, wetness, and surface condition of the debris.  

Based on their own visual ice cliff observations by the Langtang river and the villager interviews, the scientists believe that the earthquake-triggered avalanche hit Langtang first, followed then by multiple rockfalls, which were possibly triggered by the earthquake’s aftershocks.

A three-dimensional view of the Langtang mountain and village surveyed in this study. Image: K. Fujita et al.

According to the researchers’ models, the primary avalanche event unleashed 6,810,000 cubic metres of ice and snow onto the village and the surrounding area, a frozen flood about two and a half times greater in volume than the Egyptian Great Pyramid of Giza. The following rockfalls then contributed 840,000 cubic metres of debris.  

The researchers discovered that the avalanche was made up mostly of snow, and furthermore realized that there was an unusually large amount of snow. They estimated that the average snow depth of the avalanche’s mountainous source was about 1.82 metres, which was similar to snow depth found on a neighboring glacier (1.28-1.52 metres).

A deeper analysis of the area’s long-term meteorological data revealed that the winter snowfall preceding the avalanche was an extreme event, likely only to occur once every 100 to 500 years. This uncommonly massive amount of snow accumulated from four major snowfall events in mid-October, mid-December, early January and early March.

From these lines of evidence, the team concluded that the region’s anomalous snowfall may have worsened the earthquake’s destructive impact on the village.

The researchers believe their results could help improve future avalanche dynamics models. According to the study, they also plan to provide the Langtang community with a avalanche hazard map based on their research findings.  

Further reading

Qiu, J. When mountains collapse… Geolog (2016).

Roberts Artal, L. Geosciences Column: An international effort to understand the hazard risk posed by Nepal’s 2015 Gorkha earthquake. Geolog (2016).

Imaggeo on Mondays: Winter threatens to freeze over fieldwork

Imaggeo on Mondays: Winter threatens to freeze over fieldwork

This photo was taken during a fieldwork campaign following the mainshock of the deadly seismic sequence that struck central Italy starting from 24 August 2016. The magnitude 6.2 earthquake severely damaged nearby towns, claimed more than 290 lives and injured nearly 400 people in its wake.

As a geologist from the National Institute of Geophysics and Volcanology, I was in charge of measuring the manifestations of the seismic shaking (mainly fractures and landslides) on the territory. Some of the most relevant fractures were located along the mountain ridge formed by Monte Vettore (in the background of the photo) and Monte Porche (on which the photo was taken).

The new snow and the lowering temperature signaled that winter was approaching. The changing season also meant that my colleagues and I would have to rush the survey before the snow buried even the deepest fractures.

By Roberto Vallone, a technologist at the National Institute of Geophysics and Volcanology in Italy

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.