A pdf of the slides I used for a talk recently on the links between earthquake fatalities and poverty, corruption and ignorance.
Satellite data has shed new light on seismic hazard in one of the world’s most deadly earthquake zones.
Published today in Nature Communications, the study describes how tectonic strain builds up along Turkey’s North Anatolian Fault at a remarkably steady rate.
This means that present-day measurements can not only reflect past and future strain accumulation, but also provide vital information on events still to come.
The strain, which builds up as Turkey is squeezed between three major tectonic plates, has caused almost the entire length of the fault to rupture since 1939 in a series of major earthquakes gradually migrating east to west towards Istanbul.
Led by Ekbal Hussain, the team used satellite images from the European Space Agency’s Envisat mission to identify tiny ground movements at earthquake locations along the fault.
Dr Hussain explained: “Because we know so much about the fault’s recent history, we could look at the strain build up at specific places knowing how much time had passed since the last earthquake.”
The 600-plus satellite images, taken between 2002 and 2010, provided insights into the equivalent of 250 years of the fault’s earthquake repeat cycle.
Remarkably, apart from the ten years immediately after an earthquake, strain rates levelled out at about 0.5 microstrain per year, equivalent to 50mm over a 100km region, regardless of where or when the last earthquake took place.
Dr Hussain added: “This means that the strain rates we measure over the short term can also reflect what’s happening in the longer term, telling us how much energy is being stored on the fault that could eventually be released in an earthquake.”
Until the satellite era, it was difficult to get a clear picture of how strain built up on the fault. Now, satellites like Envisat, alongside the newer Sentinel-1 mission, can detect ground movements of less than a millimetre, indicating how and where strain is accumulating.
The findings suggest that some existing hazard assessment models, which presume that strain rates vary over time, need to be rethought. This is especially true for regions where there are long gaps between earthquakes, such as the Himalayas.
Co-author Professor Tim Wright said: “Discovering this consistent strain accumulation will help us to reassess how we model seismic hazards, as well as improving understanding of the earthquake cycle worldwide.”
 The full paper is: Hussain et al. (2018) Constant strain accumulation rate between major earthquakes on the North Anatolian Fault, Nature Communications
 Lead author Ekbal Hussain is now a Remote Sensing Geoscientist at the British Geological Survey
I recently gave a talk about social vulnerability and earthquake losses at the Valuing Infrastructure conference in Leeds. The talk was recorded and can now be viewed on YouTube!
An earthquake simulator in Tokyo, Japan shows off what a Magnitude 9 earthquake feels like. Scary stuff!
by Huw Goodall
Half awake, half asleep. The room is shaking. You realise you are not at home. You are in central Italy. Now the room is really shaking, you sprint over to hide under the desk as the floor moves under your feet, grabbing clothes as you go. The shaking continues, you put on the random assortment of clothes, pulling the bag you packed the night before, with the essentials to survive, close to you, wondering when the shaking will stop. Preparing mentally to be buried under the roof and hunker under the desk until the rescue team gets to you, you listen as the doors and windows rattle and bang. Then there is silence.
Pulling your shoes on (why didn’t you untie them last night!) you run into the corridor, your colleagues are out there, everyone is unhurt. Down the gloomy hotel corridor you all hurry out into the square, where slowly but surely the population of Ascoli Piceno gathers in the beautiful early morning sun. After an hour or so delay, including dashing back into the ancient building to grab field kit, interviews with the BBC and a delayed breakfast, you escape from the medieval town towards the epicentre of the earthquake.
Driving up the winding mountain roads, dodging between boulders that have been dislodged by the shaking, your team of 4 make their way towards the centre of the earthquake. As you approach, the tiny villages that dot the route show increasing signs of damage. Then you see it. The rupture. This is where the earth has been cut by the quake. The work begins. High precision surveys are taken from this site, after a brief discussion it is decided to return to where you were working the previous day and see if the fault has moved in the earthquake there too.
This involves driving through the isolated town of Castellucio, a stunning hilltop village, famous for its lentils. As you drive up the hill, the residents are in the street. Your Italian is only good enough to order food, but you can tell they are scared, confused and don’t know why you are there. You are probably the second car at most that has passed this way since the earthquake that morning. The destruction is clear, walls collapsed a pancaked building along the road, other houses simply gone. There is a helicopter landing in the street. People are everywhere.
Eventually the situation is explained in a hash of Italian and English and you are allowed to pass through, to continue to do your work as the people of the village continue to take stock. The next two weeks are non-stop field work, police checkpoints, late dinners and early starts. You measure how the fault has ruptured the surface, using a high-tech laser scanner, GPS, cameras and the good old fashioned ruler and notebook.
We spent the fortnight mapping new parts of the rupture as well as repeating measurements at some sites, to generate a picture of how the fault is moving in the days after the earthquake. This data set will be unlike any other in existence and hopefully will give us an insight into why earthquakes happen the way they do.
Huw is a PhD student in the School of Earth and Environment at the University of Leeds. His work involves using precise chemical analysis of earthquake faults to understand how they have moved in the past.
Bangladesh is one of the most disaster-prone countries in the world. In addition to frequent cyclones and drought, large areas of the country are at risk of earthquakes.
With densely populated cities, even a relatively small earthquake could have catastrophic consequences. Amrai Pari (Together We Can Do It) is harnessing the power of animation to help people be better prepared. Find out more about the project: http://bbc.in/2gsG8Tx
Since 1900, 35 earthquakes worldwide have each killed at least 10,000 people. Of these, 26 were in the Alpine-Himalayan seismic belt – a broad “crumple zone” where the African, Arabian and Indian tectonic plates collide with Europe and Asia. Most of these deadly earthquakes were caused by the rupture of faults that had not previously been identified.
Tim Wright is Professor of Satellite Geodesy at the University of Leeds and Director of the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET). His work has been at the forefront of developing the use of satellite radar for measuring tectonic and volcanic deformation.
Below is a lecture presented by Tim at the Geological Society talking about his work trying to understand the nature of seismic hazard within the Alpine-Himalayan region.
A megathrust fault could be lurking underneath Bangladesh, India and Myanmar, exposing one of the most densely populated regions in the world to the risk of a large earthquake, according to new research published in Nature Geoscience.
A new GPS study measuring tiny ground movements since 2003 in the south Asia region has found strong evidence suggesting that a large tectonic fault beneath Bangladesh and east India is seismically active.
The team, consisting of scientists from the USA, Singapore and Bangladesh, calculate that the megathrust fault could be accumulating strain energy at rates of about 15 mm per year.
Importantly, the researchers believe that the fault is “stuck” and has been storing energy for more than 400 years without a major earthquake; since the Mughal conquest of Bengal and the establishment of Dhaka as the Bangladeshi capital in the 1600s.
An earthquake occurs when the stresses become large enough that it causes the fault to break and releases all the stored energy. The 400 years of energy accumulation at 15 mm per year could result in a devastating magnitude 9 earthquake, similar in size to the Japanese quake that destroyed huge sections of the country’s northeastern coast in 2011. Such an event would have enormous consequences for more than 140 million people living within 100 km of the megathrust in Bangladesh and India.
The tectonic activity of south Asia is a consequence of the collision of the Indian subcontinent with Asia, a process that began nearly 50 million years ago and is still occurring today. This monumental collision resulted in the uplifting of Tibet and the formation of the Himalayan mountain range. Over millions of years these mountains have been slowly eroded and deposited their rich soils onto the Bangladeshi plains by a network of giant rivers. The thick sediments have made the Bangladeshi plains some of the most agriculturally productive in the world.
While the sediments can take up some of the energy along the newly proposed fault, they’re not especially stable, particularly around the rapidly developed eastern outskirts of Dhaka. If a major earthquake strikes, the sediments could even amplify the seismic waves, causing further destruction.
“Dhaka’s basically like building a city on a bowl of Jell-O [jelly],” says Steckler, lead author of the new study, implying that even small earthquake shaking could be amplified by the sediments.
The Savar building collapse in 2013, which resulted in over 1100 deaths, showed the world that building codes in Bangladesh are not strictly enforced. If buildings are collapsing on their own, it is a terrifying prospect to consider what would happen during an earthquake. The lack of preparedness is clear and it is essential for the Bangladeshi government to make long-term changes to promote greater seismic awareness and stricter enforcement of building codes.
 The original paper: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2760.html
by Camilla Watson
An earthquake of magnitude 7.8 occurred in Ecuador on the 16th April this year. With the current death toll at 654 and another 58 still missing, this is one of the most devastating disasters South America has seen in modern times. Although the earthquake epicentre was in a relatively sparsely populated area, according to the US Geological Survey the focus was shallow at 19.2km (12 miles) and located 27km (17 miles) from Muisne off the west coast of northern Ecuador, meaning the effects were stronger than expected upon the Earth’s surface.
The main initiator of earthquakes is tectonic plate movement. This particular earthquake was caused by a shallow thrust fault on or near the boundary between the Nazca and South American tectonic plates (USGS, 2016). In real terms, this means the Nazca plate is sliding beneath the South American plate, and the build-up of energy due to friction is realised in one sudden slip, causing the earthquake and its aftershocks (Wald, 2009). Similar systems have caused some of the strongest earthquakes in the world, including the 1960 Chile earthquake of magnitude 9.5 – the largest ever recorded. Due to the presence of the subduction zone, this particular area within Ecuador is known to be prone to earthquakes, with many of the quakes occurring at 0-70km depths beneath the Earth’s surface. This often causes the consequences to be more devastating. The subduction system is also responsible for the formation of the Andes, the longest mountain chain in the world, and the high levels of volcanism within the area (USGS, 2016).
Scientists have been speculating as to whether the 2016 Ecuador earthquake was linked to the magnitude 7.0 Japan earthquake that occurred the day before, on the 15th April, with a shallow focus at 10km depth (Byrd, 2016). The idea behind this is something known as ‘remote triggering’, whereby a magnitude 6.5 earthquake in Japan would have caused slip along the boundaries of the tectonic plates on the other side of the Pacific Ocean, which triggered the tremors that made up the earthquake (Brown, 2016). However, this may also be chance due to both localities being situated on the Ring of Fire, an area known to be extremely tectonically active. Research so far shows no evidence for remotely triggered earthquakes to reach magnitudes above 5, making this particular situation between Ecuador and Japan either the first recorded case of its kind, or a coincidence. However, there has not yet been enough time for thorough research, but many earth scientists will now be focusing on the possibilities of using this information to help us to forecast and prepare for earthquakes in the future.
 D. Byrd, (2016), Powerful earthquakes in Japan and Ecuador, EarthSky, [Online], Accessed 25/04/2016: http://earthsky.org/earth/powerful-earthquakes-japan-ecuador-april-2016
 E.K. Brown, (2016), Are the Japanese and Ecuador earthquakes related?, The Conversation, [Online], Accessed 25/04/2016: http://phys.org/news/2016-04-japanese-ecuador-earthquakes.html
 Fox News, (2016), Death toll in the powerful Ecuador Earthquake rises to 654, Fox News, [Online], Accessed 25/04/2016: http://www.foxnews.com/world/2016/04/24/death-toll-in-powerful-ecuador-earthquake-rises-to-654.html
 L. Wald (2009), The Science of Earthquakes, The Green Frog News, USGS, [Online], Accessed 25/04/2016: http://earthquake.usgs.gov/learn/kids/eqscience.php
 USGS, (2016), M7.8 – 27km SSE of Muisne, Ecaudor, United States Geological Survey (USGS), [Online], Accessed 25/04/2016: http://earthquake.usgs.gov/earthquakes/eventpage/us20005j32#general
Camilla is a 3rd year undergraduate student in the School of Earth and Environment at the University of Leeds. She likes to combine her passion for travel with her love of geology. Check out her blog at: www.geologyandme.weebly.com