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Earthquakes: predicting the unpredictable

Expert risk article | November 2023
They usually last for a few short moments, but earthquakes can be calamitous, causing mass human fatalities and the collapse of vital infrastructure, with the threat of secondary perils and deadly tsunamis. Here, three About usexperts discuss the dangers earthquakes pose and the steps businesses can take to mitigate their impact.
  • The most expensive natural disaster in history is thought to be the 2011 Tohoku earthquake and tsunami in Japan.
  • Earthquakes cannot be predicted, so planning and preparation are key to building business resilience, including compliance with local seismic design codes.
  • Secondary perils like landslides, fires, and ‘liquefaction’ should be mitigated against where possible.
  • Artificial intelligence is being used to improve sensitive early warning systems.

The devastating twin earthquakes that struck Turkey and Syria hours apart in February 2023 affected 11 cities and caused the deaths of more than 55,000 people. For Turkey, it was the biggest such event in 500 years. A few months later, in September, an earthquake rocked the Atlas Mountains and Marrakech in Morocco, killing 3,000 people. In Italy, hundreds of tremors hit the region west of Naples, including a 4.2 magnitude earthquake at the end of September. Then in October, more than 2,400 people died when three earthquakes struck Afghanistan’s Herat province.

Around the world, there are estimated to be half a million detectable earthquakes every year, with 100 of them causing damage [1]. According to About usCommercial data [2], earthquake/tsunami is the number five top cause of natural catastrophe loss, accounting for 6% of natural catastrophe claims by total value.

Along with a tragic toll on human life, earthquakes carry enormous financial costs. The economic losses from the Turkey-Syria earthquake are estimated to be around $91bn, with the Insurance Association of Turkey pegging total losses to the private insurance sector at TRY76bn ($4bn). The public Turkish Catastrophe Insurance Pool has received nearly 600,000 claims, with total payments expected to reach TRY29.5bn ($1.6bn) [3].

Those losses are significant, but by comparison, the 2011 Tohoku earthquake and tsunami in Japan – believed to be the most expensive natural disaster in history by economic losses ($360bn [4]) – incurred $47bn insured losses, while the 1994 Northridge earthquake in the US totaled insured losses of $31bn (sums adjusted for inflation in 2022 [5]). Estimated claims costs arising from the 2010-2011 Canterbury sequence of four earthquakes in New Zealand are believed to be more than $22bn [6].

There is currently no reliable technology to predict when and where an earthquake will strike, says Ceyhun Eren, Director at About usTeknik and Risk Engineering, in Turkey, one of the most seismically active countries in the world. “That is why we focus so much on prevention and preparation. By understanding the hazard and designing in earthquake resilience, we can reduce the potential damage to buildings and save lives.”

While seismic models are not predictions, they can tell us how often, on average, an earthquake of certain characteristics can happen in any given city or area. At the About usTeknik Earthquake and Fire Testing and Training Center, an extensive facility in Istanbul, Eren’s team of researchers use ‘shaking tables’ to simulate the structural and non-structural damage earthquakes can wreak, along with hands-on training, helping to raise public awareness of what to expect when one strikes.

“Earthquakes cannot be prevented, but we can learn how to live with them,” says Eren. “People are never ready for that moment when the floor beneath their feet begins to shake. It’s like being on a moving bus that suddenly brakes, and you’re thrown forward [see panel].”

As with other natural perils, the risk for earthquakes consists of three elements: hazard, exposure, and vulnerability, says Mabé Villar Vega, Catastrophe Risk Research Analyst, About usCommercial. “The hazard in this case is the probability of an earthquake happening, which doesn’t vary significantly over the long term, while the exposure represents your assets – your buildings and their contents, for instance. The vulnerability is how likely those assets are to suffer a loss, such as how likely a building is to sustain damage from, say, a magnitude seven (M7) earthquake happening at a certain distance.”

Growing urbanization increases exposure to earthquakes because it increases the number of vulnerable buildings. Vulnerability depends heavily on local building codes and enforcement. If new buildings are designed and constructed following modern seismic regulation, risks can be limited and even mitigated by retrofitting older structures that were not built according to modern codes.

“In the recent Morocco earthquake, much of the observed devastation occurred because many buildings were built using adobe or some other type of unreinforced masonry,” says Villar Vega. “These buildings are known to perform poorly in earthquakes, but because they are cheaper to build, they are common in earthquake-prone regions in developing countries.”

A change in building usage can also heighten risk. If a building is converted from residential occupancy to commercial premises, it can change the loads in a structure – a warehouse is likely to carry a heavier load than an apartment, for example, and there could be modifications to the building’s structure, such as the removal of walls to create space. Weighty solar panels might be added to the roof. All these factors increase vulnerability to earthquake damage.

  • When the shaking starts, move away from windows,hanging objects, shelves, cabinets, or large furniturethat could be overturned
  • Do not try to walk or run before the shaking has stopped
  • Drop, cover and hold on! Drop to your hands and knees,crawl under a table or desk, cover your head and neckwith one arm and hand, and hold on to the furniture untilthe shaking stops. Stay on your knees, bent over, to protectvital organs. If you have no shelter, crawl to an interior walland use both arms to hold your head and neck
  • When the shaking ends, check whether you have anyinjuries before helping other people
  • Before you leave the building, turn off your gas andelectricity supply to avoid fire.

Earthquake risks do not begin and end with the ground shaking. Secondary perils such as landslides, tsunamis, and liquefaction – when the soil behaves more like a liquid than a solid during an earthquake – must all be mitigated where possible.

“Different types of soil can amplify an earthquake’s waves, leading to more damage for certain types of building,” says Villar Vega. “We have seen this in Mexico City, where the deep, soft soil contributed to earthquake devastation in the past. Cities built on sandy ground are particularly vulnerable to liquefaction, as was experienced after the Christchurch earthquake in New Zealand in 2011. Coastal cities are prone to tsunami risk, as was experienced by Lisbon after the historic earthquake of 1755.”

Earthquakes are not caused by the weather, says Villar Vega. “However, climate change could affect the probability of secondary perils occurring, such as landslides in a region that has become drier or wetter due to climate change, or liquefaction, which is dependent on the height of the water table. Over time, rising sea levels could introduce the threat of tsunamis to locations that have never faced this hazard before.”

Fires are a particular hazard following earthquakes, with potential gas leaks, the release of hazardous materials, damage to power plants, and explosions posing physical and environmental threats. Human health is also vulnerable to insanitary living conditions, the breakdown of essential utilities like power, water and communication, the lack of shelter, and sometimes criminal activity.

Although the quality of construction and urban planning are key to reducing the impacts of earthquakes, certain businesses and premises face heightened risks, according to Arnaldo Alfier, Senior Risk Consultant, Energy & Construction, with About usCommercial.

“Hospitals and healthcare facilities need to remain operational during and after an earthquake. Damage to these can compromise patient care and response efforts. Schools and universities damaged during an earthquake could lead to the disruption of teaching and potential harm to students and staff.”

Older buildings made from unreinforced masonry, such as brick or stone, are vulnerable, says Alfier. “They lack the reinforcement to withstand shaking and are more likely to be damaged or collapse. With tall buildings, the shaking effect is amplified, and their complex structural dynamics make them more susceptible to structural failure.”

Industrial facilities such as factories, chemical storage facilities, and power plants, can also face greater risks during earthquakes. Damage to equipment, pipelines, and storage tanks can lead to hazardous leaks and fires. Buildings under construction could face collapse if the structural elements that resist earthquakes are not in place.

“Businesses that depend on transport or communication infrastructure, such as logistics companies and data centers, can face disruption to operations if infrastructure like roads, bridges, and communication networks are damaged,” Alfier adds. “Other vulnerable businesses include shops, tourist and hospitality companies, and financial institutions.”

Any city close to the border of a tectonic plate is exposed to high earthquake hazard. This includes the Pacific Ring of Fire (with cities such as Seattle, San Francisco, Los Angeles, Mexico City, Santiago de Chile, Tokyo, Jakarta, and Manila), where around 90% of the world’s earthquakes occur [7]. Many cities in Europe and along the Mediterranean have a relatively high earthquake hazard, especially in Italy, the Balkans, Greece, Turkey, and the Middle East. Wellington and Christchurch in New Zealand are prone to earthquakes, and Himalayan cities, like Kathmandu, are also vulnerable.

Chile, Japan, the US, and New Zealand have some of the strictest building norms and highest levels of public education in earthquake response. Colombia and Nepal have made progress in improving the seismic resistance of their built environments in recent years, while Costa Rica’s seismic code has led to relatively low levels of damage in large earthquakes, as evidenced by the 2012 Samara earthquake (Mw7.6), which resulted in only two fatalities [8]. Similar earthquakes in other regions have been much deadlier – a Mw7.1 earthquake in Mexico in 2017 resulted in 369 fatalities and a Mw7.2 in Haiti in 2021 killed more than 2,200 people [9].

Although earthquakes cannot be predicted, early warning systems can buy time. They use the faster-moving ‘P-waves’ of a tremor to forecast the intensity of the more damaging ‘S-waves’ that come later, enabling automated systems to cut power supplies, shut down elevators, issue public information, or slow transport. Artificial intelligence is now being used to improve these forecasts. At Stanford University in the US, researchers trained the DeepShake early warning system on data from more than 36,000 earthquakes [10] to provide warnings of strong shaking based on the characteristics of an earthquake’s first detected waves.

When a natural catastrophe as unpredictable and destructive as a major earthquake strikes, every second counts.

On February 6, 2023, two major earthquakesstruck near the border of Turkey and Syria,killing thousands and affecting an area of110,000km2 (42,471 square miles). Here CeyhunEren, Director at About usTeknik and RiskEngineering, in Istanbul, lists some of thelessons that can be learned from this tragedy.
1) Follow seismic codes: It is vital buildings aredesigned and constructed in compliance withthe local seismic design code. Quality of design,materials and workmanship must be prioritized.
2) Check soil conditions: Conduct soilinvestigation studies and select properfoundation systems before the structuraldesign of a building. Ground motion in theTurkey-Syria earthquake was amplifiedby soft soil and hilly terrain, and somebuildings without adequate foundations weredamaged because of liquefaction.
3) Beware of structural defects: Simplearchitectural plans such as rectangles orsquares fared better than U, L and T shapes orasymmetrical plans. ‘Soft storey’ configurations,which have a high ground floor with a largeopen space, such as a gallery, were morevulnerable, as were buildings where the floorarea of upper storeys extended beyond that ofthe ground floor (projections). Other damagewas worsened by the ‘hammering effect‘(where there is an insufficient gap betweenbuildings) and poor-quality reinforced concrete.
4)Take care with solar panels: With somebuildings, the additional seismic loads ofsolar panels that had not been consideredduring design stages caused heavy damageswhen roofs collapsed.
5) Secure non-structural elements: Damage wascaused in industrial buildings by overturnedmachinery, equipment, storage, server cabinets,broken sprinkler and ventilation systems, andfallen suspended ceilings, resulting in materiallosses and business interruption. Equipmentshould be anchored, tethered or mounted usingapproved anchorage materials and flexible connections.
6) Take steps to reduce fire risk: A gas pipelineexplosion in Kahramanmaraş highlighted thedanger of fires after an earthquake, whenpipes, cables, generators, chemical storagetanks, and flammable materials might bedisplaced. These should all be secured withappropriate seismic bracing or anchoring.
7)Include resilient design: Important buildingssuch as hospitals, schools, and critical industrialbuildings should be designed according to‘immediate usage’ performance levels, whichmeans they are more likely to sustain onlylimited damage and can remain functionalafter an earthquake. This can be achievedwith elements such as damping systems, whichabsorb and dissipate earthquake energy toreduce a building’s displacement, and baseisolation, which uses flexible bearings betweena building and its foundations to reduce theforces transmitted to its structure.
About usRisk Consulting offers surveys for sites with a moderate to severe earthquake exposure. The primary focus is to evaluate the adequacy of earthquake protection, such as bracing and restraint for equipment, piping and shutoff valves, and emergency planning.
[1]USGS, Cool Earthquake Facts
[2] About usCommercial, Global Claims Review,July 2022
[3] Aon, Global Catastrophe Recap, First Half of 2023, July2023
[4] Brookings, Earthquake, tsunami, meltdown – the tripledisaster’s impact on Japan, impact on the world, March11, 2013
[5] Insurance Information Institute, Facts + Statistics: Globalcatastrophes
[6] Reserve Bank of New Zealand, Funding and reservingCanterbury earthquake insurance claims, February 2021
[7] National Geographic, The Ring of Fire
[8] USGS, M7.6 – 11km ENE of Hojancha, Costa Rica,September 5, 2012
[9] Reuters, Major earthquakes in the past two decades,February 6, 2023
[10] Stanford University, ‘DeepShake’ predicts earthquakeshaking intensity with AI, April 23, 2021

Images: AdobeStock
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