Tag Archives: Earthquake

The Nepal Earthquake: What We Know So Far

Delhi, India also at high risk of earthquakes from the same collision zone

The earthquake in Nepal is very much a developing story. However, based on what we know, it’s shaping up to be the worst natural disaster this calendar year, particularly because Nepal is remote, economically challenged, and not resilient to an earthquake of this magnitude. The ground shaking appears to have been stronger in Kathmandu than the 1934 earthquake, possibly making it the largest we’ve seen in Nepal in almost a century.

As of April 29, Time Magazine reports that the death toll has crossed 5,000. It’s expected that casualties could surpasses 10,000, as rescue efforts continue.

While it is too early to draw substantial conclusions about the disaster—and the final casualty number—we are able to share some insight into the event and risk in the area:

Nepal EQ Map 1

Most large earthquakes in this region occur along the plate boundary collision zone:

In this region, the Indian continent dips beneath the Tibetan plateau. The Himalayan mountain chain and Everest are products of this collision zone, and the area at risk stretches from Assam and southern Bhutan to the east through Nepal to the mountains of northern Pakistan in the west. The magnitude 7.6 earthquake in Kashmir in 2005, which caused terrible damage to villages either side of the Pakistan-India border resulting in 86,000 fatalities, occurred along this plate boundary.

Nepal’s fragile economy will be affected:  Nepal is one of the world’s poorest countries. The country’s main revenue sources are agriculture and tourism, including foreigners looking to scale Mount Everest. Reports indicate that the damage caused in recent days could substantially set back the economy of Nepal.

Kathmandu was hit hardest:The fault rupture of the Nepal earthquake extended eastward from its epicenter, passing underneath the city of Kathmandu.

Historic buildings throughout the city have been reduced to rubble. Darbar Square, which attracts millions of tourists annually and is vital for the Nepalese economy, has been razed. An overwhelming majority of homes in what’s known as the Gorkha district have been destroyed. Furthermore, many villages in the region needing assistance are in mountainous areas, making rescue efforts difficult.

Structures in Nepal were already at risk: The Nepalese population resides in unreinforced masonry structures that are highly vulnerable to earthquake ground shaking. Secondary hazards are of concern as well—including landslides and liquefaction.

Aid efforts are already helping to make Nepal more resilient

The widespread damage to infrastructure will be a significant setback for Nepal, which relies on agriculture and tourism. Organizations such as Build Change are already on site helping affected communities to start rebuilding their homes using disaster-resistant designs to increase the country’s resilience to future earthquakes. If you would like to support Build Change’s work, you can donate to their fund by clicking here.

Delhi, India is at high risk of earthquakes from the same collision zone

Between Gujarat and the Himalayas lies the mega-city of Delhi, which is exposed to significant earthquake risk from the surrounding plate movement.

EQ_Nepal_GIS_29Apr2015_v4

Delhi’s seismic risk comes from both the Himalayan thrust zone, where the recent Nepal earthquake struck, and the transition zone between the stable continent and the active plate boundary—also the site of the 2001 M7.7 Gujarat earthquake, which resulted in 20,000 fatalities.

According to the Bureau of Indian Standards’ seismic zoning map, Delhi is within a “high seismic risk zone.” Combined with an older building stock made of unreinforced masonry and reinforced concrete, the city’s people, buildings, and economy are at significant risk.

Delhi is the northern industrial hub of India, with significant manufacturing exposure, including textiles, chemicals, fertilizers, and leather goods. Delhi’s service sector has also grown enormously in recent years, with expansion in information technology, telecommunications, and banking.

Projects piloting risk reduction in the city—through building retrofits or enhanced building inspections—have been underway and offer some degree of comfort that the seismic risk issues in Delhi are being acknowledged.

We will continue to monitor the situation in Nepal. If you have questions about the disaster please feel free to ask them in the comment section.

How should manmade earthquakes be included in earthquake hazard models?

Oklahoma, Colorado, and Texas have all experienced unusually large earthquakes in the past few years and more earthquakes over magnitude 3 than ever before.

Over a similar time frame, domestic oil and gas production near these locations also increased. Could these earthquakes have been induced by human activity?

Figure 1: The cumulative number of earthquakes (solid line) is much greater than expected for a constant rate (dashed line). Source: USGS

According to detailed case studies of several earthquakes, fluids injected deep into the ground are likely a contributing factor – but there is no definitive causal link between oil and gas production and increased earthquake rates.

These larger, possibly induced, earthquakes are associated with the disposal of wastewater from oil and gas extraction. Wastewater can include brine extracted during traditional oil production or hydraulic fracturing (“fracking”) flowback fluids – and injecting this wastewater into a deep underground rock layer provides a convenient disposal option.

In some cases, these fluids could travel into deeper rock layers, reduce frictional forces just enough for pre-existing faults to slip, and thereby induce larger earthquakes that may not otherwise have occurred. The 2011 Mw 5.6 Prague, Oklahoma earthquake and other recent large midcontinent earthquakes were located near high volume wastewater injection wells and provide support for this model.

However, this is not a simple case of cause and effect. Approximately 30,000 wastewater disposal wells are presently operated in the United States, but most of these do not have nearby earthquakes large enough to be of concern. Other wells used for fracking are associated with micro-earthquakes, but these events are also typically too small to be felt.

To model hazard and risk in areas with increased earthquake rates, we have to make several decisions based on limited information:

  • What is the largest earthquake expected? Is the volume or rate of injection linked to this magnitude?
  • Will the future rate of earthquakes in these regions increase, stay the same, or decrease?
  • Will future earthquakes be located near previous earthquakes, or might seismicity shift in location as time passes?

Induced seismicity is a hot topic of research and figuring out ways to model earthquake hazard and possibly reduce the likeliness of large induced earthquakes has major implications for public safety.

From an insurance perspective, it is important to note that if there is suspicion that the earthquake was induced, it will be argued to fall under the liability insurance of the deep well operator and not the “act of God” earthquake coverage of a property insurer. Earthquake models should distinguish between events that are “natural” and those that are “induced” since these two events may be paid out of different insurance policies.

The current USGS National Seismic Hazard Maps exclude increased earthquake rates in 14 midcontinent zones, but the USGS is developing a separate seismic hazard model to represent these earthquakes. In November 2014, the USGS and the Oklahoma Geological Survey held a workshop to gather input on model methodology. No final decisions have been announced at this time, but one possible approach may be to model these regions as background seismicity and use a logic tree to incorporate all possibilities for maximum earthquake magnitude, changing rates, and spatial footprint.

Figure 2: USGS 2014 Hazard Map, including zones where possibly induced earthquakes have been removed. Source: USGS

A Decade Later – Reconsidering The Indian Ocean Earthquake and Tsunami

This December marks the 10-year anniversary of the Indian Ocean earthquake and tsunami, a disaster that killed more than 230,000 people in 14 countries. The disaster hit Thailand and Indonesia especially hard and is considered one of the ten worst earthquakes in recorded history based on damages.

Click here for full size image

In advance of the anniversary on December 26, 2014, Dr. Robert Muir-Wood, RMS chief research officer, and Dr. Patricia Grossi, RMS senior director of global earthquake modeling, hosted their second Reddit Science AMA (Ask Me Anything). Back in October, Muir-Wood and Grossi hosted another AMA on the 25th anniversary of the Loma Prieta earthquake in the San Francisco Bay Area.

The latest Reddit thread generated almost 300 comments. Muir-Wood and Grossi discussed topics including: early warning systems for disasters like tsunamis, what variables are considered in catastrophe models, and if better building design can protect against natural disasters – particularly tsunamis. Highlights of the chat follow:

What kind of structural elements or configurations are best to combat or defend against these disasters?

Muir-Wood: There have been research studies on buildings best able to survive tsunamis. The key is to make them strong (from well engineered reinforced concrete) but with ground floor walls running parallel with the shoreline that are weak, so that the walls can be overwhelmed without threatening the whole building.

The 2004 Indian Ocean tsunami took a lot people by surprise due to the lack of a tsunami warning system even though there was a gap between the earthquake and the tsunami. If there was a tsunami warning system in place at the time would that have decreased the death toll by a lot, or not make too much of a difference considering how strong the tsunami was.

Grossi: Early warning systems are excellent tools for reducing the loss of life during an earthquake-induced tsunami event. But education is one of the easiest ways to reduce tsunami life loss. Such education needs to include knowledge of the cause of a tsunami and its association with the largest earthquakes to help individuals understand how their own observations can help them take appropriate action (e.g., seeing the water recede from the coastline). In essence, official warning systems can provide only part of the solution, as information can never be effectively disseminated to everyone along a coastline. With only 10 to 30 minutes warning in the nearfield of major tsunamis, it is imperative that people are taught to take their own action rather than wait for official instruction.

Show me the coolest tsunami video.

Muir-Wood: There are amazing videos of the Japan 2011 tsunami. I wouldn’t pick just one of them – but recommend you watch quite a few – because they are interestingly different. The most amazing feature of the tsunami is the way the water can continue to rise and rise, for five or ten minutes, apparently without end. And then how the people watching the tsunami, climb to higher locations and then realize that if it keeps rising there will be nowhere for them to go.

Was there anything we missed you wanted to discuss? Please let us know in the comments. 

Managing Risk 10 Years After the 2004 Indian Ocean Earthquake and Tsunami

On Sunday, December 26, 2004 at approximately 8 a.m. local time, a massive earthquake occurred along the Indian–Burma plate boundary off the coast of Sumatra, Indonesia. Rupturing over 1,200 km of the Sunda Trench, the magnitude of the earthquake has been estimated between M9.0 and M9.3—with the U.S. Geological Survey’s Centennial Earthquake Catalog estimating M9.1. Occurring at a fairly shallow depth—less than 30 km—the earthquake generated a basin-wide tsunami that inundated coastlines across the Indian Ocean and caused run-up waves farther afield, impacting the eastern coastline of Africa. By the end of the day, it was apparent that the event was going to emerge as one of the worst natural disasters in modern times.

Click here for full size image

Economic Toll and Recovery

Overall economic losses from the 2004 disaster were approximately $10 billion, with the majority of loss attributed to the damage in the Indonesia, Thailand, Sri Lanka, and India. The large majority of property damage was caused by the tsunami waves. Along coastlines of most of the affected countries, buildings were situated closer to sea level than is typical of higher latitudes, exacerbating the impacts.

In the aftermath of the event, the international relief efforts across the Indian Ocean were seen as fairly effective. But the longer-term recovery work in certain regions has struggled—due to the overwhelming numbers of people displaced from their homes. There are, of course, examples of well-executed reconstruction efforts. Build Change—a partner organization of RMS—has worked with tsunami survivors in Banda Aceh, Sumatra to rebuild safe, sustainable homes. Ten years after the event, evidence of the destruction wrought by the tsunami remains in the high-impacted areas.

Humanitarian Impact 

While tsunami in the Indian Ocean have certainly occurred many times before, from the perspective of modern history, the human casualties from the 2004 Indian Ocean Earthquake and Tsunami have no historical equal. More than 225,000 people lost their lives in the disaster, with most of the loss of life occurring in the near field in Sumatra, Indonesia. In Indonesia, the tsunami destroyed virtually every village, town, road, and bridge along a 170-km stretch of coast less than 10 m above sea level. Sri Lanka’s Eastern and Southern provinces were severely impacted, with fatality rate among the population within 1 km of coast between 15% and 20%. In India, entire villages in Tamil Nadu were destroyed.

In Thailand, the tsunami affected local inhabitants and foreign tourists in the densely inhabited Phuket Island. The fatalities among the tourists were a significant proportion of the overall loss of life, as many were on the beach or in hotels near the sea at the time the tsunami waves struck. In addition, the initial tsunami wave in Phuket, which was east of the rupture, began with a receding wave. Many of the tourists (not indigenous to tsunami-prone coastal regions) were unfortunately not familiar with the nature of tsunami waves. In many (but not all) tsunami, the first movement of the sea is a withdrawal. Any occasion when the sea level recedes rapidly and inexplicably should be taken as a signal for immediate flight to higher ground.

Managing Tsunami Risk in the Aftermath

The 2004 Indian Ocean Tsunami highlighted inherent vulnerabilities in the world’s coastlines and the people who live there. Coastal populations are on the increase in many parts of the world, mostly due to the exploitation of sea resources or tourism-related activities. Adequate tsunami mitigation measures— such as tsunami warning systems, education, and land use planning—can be put in place to save lives, property, and the livelihoods of those living on the coast.

Although the impact of the 2004 disaster on the global insurance industry was minimal, it alerted the world to the dangers of tsunami hazards. Worldwide response to the 2004 disaster resulted in the establishment of the Indian Ocean Tsunami Warning and Mitigation System in 2006.

Ten years hence, the world has seen two more earthquake-induced tsunami events—in the 2010 M8.8 Maule, Chile Earthquake and in the 2011 M9.0 Tohoku, Japan Earthquake—causing many clients to inquire where else in the world can events like these happen?

Chennai, India

9:30 a.m. local time

On the Indian peninsula, the hardest-hit areas were on India’s southeastern coast, in the state of Tamil Nadu, where close to 8,000 perished. Chennai, the capital of Tamil Nadu, has rebounded to become one of the Rockefeller Foundations’ “100 Resilient Cities” for its commitment to minimizing the impact of flooding in low-lying coastal areas and adopting a tsunami early warning system.

Just north of the earthquake’s epicenter, India’s Andaman and Nicobar islands were struck by waves reaching 4 to 15 m (13 to 50 ft) within 10 minutes of the earthquake. The death toll reached 7,000, with many more missing and presumed dead.

Distance from Epicenter

2,020 km

(1,260 mi)

Wave Height

5 m

(16 ft)

Time from initial rupture

3 hours

Banda Aceh, Indonesia

8:30 a.m. local time

The first wave reached Sumatra, Indonesia’s largest island, approximately 30 minutes after the initial rupture. Banda Aceh, the area hardest hit by the tsunami and closest major city to the earthquake’s epicenter, sustained more than 31,000 casualties in the city alone. Entire towns in the surrounding areas, some with populations of more than 10,000, vanished. More than 600,000 people in Aceh’s fishery and agricultural sectors lost their livelihoods.

Four times more women than men were killed—not just in Indonesia, but India and Sri Lanka as well—as many men were fishing, while women were on the beach, waiting for the fishermen to return, or at home, minding their children.

Distance from Epicenter

260 km

(160 mi)

Wave Height

30 m

(100 ft)

Time from initial rupture

30 min

Patong Beach, Thailand

9:30 a.m. local time

Tourism is one of Thailand’s key economic sectors, comprising about 12% of its overall GDP, with the greatest economic development along Thailand’s western coast. Khao Lak, Ko Phi Phi, and Phuket, with their pristine beaches, placid waters, and coral reefs, are among some of the most visited places on Earth. They were also the areas hit hardest by the tsunami.

The earthquake struck during the height of Thailand’s tourist season, causing close to 5,400 confirmed deaths, with many thousands more missing and presumed dead.

Distance from Epicenter

580 km

(360 mi)

Wave Height

6 m

(20 ft)

Time from initial rupture

1.5 hours

Galle Port, Sri Lanka

10:00 a.m. local time

Before the tsunami hit, elephants were observed running away from Patanangala beach in Yala National Park, directly in the tsunami’s path. Flamingos, goats, and buffaloes also moved to higher ground. All but two water buffaloes were unharmed.

When the waves came, Sri Lanka’s eastern and southern provinces were the hardest hit. In the coastal town of Telwatta, the tsunami struck an overcrowded train packed with passengers for the Buddhist full moon and Christmas holiday weekend. More than 1,700 lives were lost in what became the worst humanitarian disaster in railroad history.

Distance from Epicenter

1,750 km

(1,100 mi)

Wave Height

6 m

(20 ft)

Time from initial rupture

3 hours

Wave Height

6 m

(20 ft)

Northern Sumatra, West Coast

7:58 a.m. local time

The M9.1 earthquake struck 160 km (100 mi) off the northwest coast of Sumatra, Indonesia, generating the deadliest tsunami in history. With a rupture length of more than 1,200 km (750 mi), the earthquake released energy equivalent to 475 megatons of TNT, and shot a massive water column into the air.

The water settled back into the open ocean as a barely perceptible swell of only 50 cm (1.6 feet)—but moved at speeds of more than 600 km/hr (370 mph). It slowed toward the coast, inundating Sumatra with waves of up to 30 m (100 feet), leaving more than 225,000 people missing or presumed dead, and displacing 1.5 million more.

Countries impacted

14

Total insured losses

$1 billion

Total economic losses

$10 billion

Canada earthquake risk 85 years after the Grand Banks earthquake and tsunami

November 18 marked the 85th anniversary of one of the largest and deadliest earthquakes in Canadian history, one that reiterates the importance of managing all drivers of earthquake risk effectively in the region.

The 1929 Grand Banks earthquake and tsunami was a magnitude 7.2 event that occurred just after 5:00 p.m. NST approximately 155 miles south of Newfoundland and was felt as a far away as New York City and Montreal. The earthquake caused limited damage on land and water, including minor landslides, but triggered a significant tsunami that was recorded as far south as South Carolina and as far east as Portugal.

Sea levels near the Newfoundland coast rose between 6 and 21 feet, with higher amounts recorded locally through narrow bays and inlets, and the tsunami claimed 28 lives. Had this event occurred near a more populated region, such British Columbia or Québec, the impacts could have been much worse.

Figure 1: A home in Newfoundland gets dragged out of a nearby cove following the 1929 Grand Banks earthquake and tsunami. Source: Natural Resources Canada

An event like this shows just how complex the Canadian earthquake risk landscape can be and how important it is to keep that view of risk as up-to-date and accurate as possible. On average, Canada experiences approximately 4,000 earthquakes each year. Most are small, but some can be large, particularly along the west coast near Vancouver and Victoria. There, in what is known as the Cascadia Subduction Zone, the Juan de Fuca plate is sliding underneath North America, causing subduction earthquakes, which tend to be less frequent but more severe than other Canadian seismic sources.

RMS has been modeling Canadian earthquake risk since 1991, with the last model update in 2009. The model inherently or explicitly includes the impacts of nearly all drivers of earthquake damage in that part of the world, from ground shaking, landslides, and liquefaction to fire following.

In building, updating, and validating the model over the years, RMS has collaborated with leading Canadian researchers and engineers, including representatives from what is now known as Natural Resources Canada (NRCan). RMS also maintains strong relationships with key insurance organizations and regulatory bodies, such as the Office of Superintendent of Financial Institutions and the Insurance Bureau of Canada, to play a key role in influencing guidelines and practices throughout the Canadian earthquake market.

The next update to the RMS Canada Earthquake Model is targeted for 2016 as part of a larger RMS North America Earthquake Models update. Among other enhancements, the model will incorporate the latest seismic hazard data (2015), internal research by the RMS seismic hazard development team, and introduce a probabilistic earthquake-induced tsunami model that will include losses from inundation along impacted coastlines.

Together, these updates will reflect the latest view of earthquake hazard in Canada, enabling the market to price and underwrite policies more accurately, and manage earthquake portfolio aggregations more effectively.

Your Excellent Questions On Earthquakes

Today marks the 25th anniversary of the magnitude 6.9 Loma Prieta earthquake which rocked California’s San Francisco Bay Area on October 17, 1989. To commemorate the anniversary and raise awareness about resilience against earthquakes, Dr. Robert Muir-Wood, RMS chief research officer, and Dr. Patricia Grossi, RMS senior director of global earthquake modeling, hosted a Reddit Science AMA (Ask Me Anything).

They discussed a number of topics; participants expressed curiosity not just for routine details like the best immediate action in the event of a quake, but also what fault lines are at risk and the finer points of earthquake insurance.

Here are just a few of the subjects they tackled in a conversation that generated close to 200 comments by Thursday afternoon – you can also read the entire Reddit thread.

Is the Bay Area is better prepared [now] than for the Loma Prieta quake? What role have you (or other scientists) played in planning?

Grossi: There’s been a lot of work by PG&E, BART, and other agencies to mitigate earthquake risk – as well as the new span of the Bay Bridge. In addition, the California Earthquake Authority has been encouraging mitigation – and have mitigation incentives if you retrofit your home to withstand earthquake ground shaking. Scientists can help by creating strategic plans or perform cost-benefit analyses for mitigation/retrofit.

Is there a link between fracking and earthquakes?

Muir-Wood: The term ‘earthquake’ can cover an enormous range of sizes of energy release. Fracking may sometimes trigger small shallow earthquakes or tremors. One day there might be a bigger earthquake nearby and people will argue over whether it was linked to the fracking. The link, however, will remain tenuous.

Am I being overcharged for earthquake insurance? I was charged $1,500 a year with a 15 percent deductible.

Grossi: Premiums associated with the coverage seem high (as generally double premiums here in California). However, they are based on price-based pricing. The coverage is meant to be a ‘minimum’ coverage – and provide protection for the worst-case scenario.

Is Tokyo due for another big earthquake?

Muir-Wood: The Big One happened beneath Tokyo in 1923, and before that a similar Big One (not quite on the same fault) occurred in 1703. The 1923 earthquake is not so likely to come around again. However, there was a M7 earthquake in 1855 that occurred right under Tokyo and may be the type of damaging earthquake we can expect. It could do a lot of damage.

 

Was there anything we missed you wanted to discuss? Please let us know in the comments. 

The Next Big One: Expert Advice On Planning For The Inevitable

The 25th anniversary of the Loma Prieta earthquake provides an opportunity to remember and reflect about what we lost. It also offers an opportunity to think about how we can better plan and prepare for an inevitable earthquake on the Bay Area’s precarious fault lines.

While we can’t accurately predict when an earthquake will strike, we can say there’s more at risk here then there was in 25 years ago; the Bay Area’s population has grown 25 percent and the value of residential property is now $1.2 trillion. A worst-case, magnitude 7.9 earthquake on the San Andreas Fault could strike an urban center with 32 times the destructive force of Loma Prieta, potentially causing commercial and residential property losses over $200 billion.

As part of our activities around the Loma Prieta anniversary, we gathered experts at a roundtable to discuss how to improve resilience in the Bay Area. Here are some of their lessons and observations:

Patrick Otellini, Chief Resilience Officer, San Francisco
Think about people when crafting public policy:

Preparing for an earthquake is an enormous task. San Francisco is working to retrofit 4,800 buildings during the next seven years. You have to get the right people at the table when crafting policy changes and understand how citizens will be affected. There needs to be a dual focus: protect the public interest while building consensus on changes that protect safety and health.

Dr. Patricia Grossi, Earthquake expert and senior director of product model management, RMS
Don’t short change risk modeling:

Risk modeling helps us assess how we are planning for the next big event, highlights uncertainties and leads to thorough preparation. But any analysis shouldn’t just consider dollar signs; it should analyze the worst-case scenario and what an earthquake would do to our lives in the immediate days and weeks after.

Kristina Freas, Director of Emergency Preparedness, Dignity Health
Retrofit hospitals and prepare to help the most vulnerable:

Hospitals are little cities. The same issues with supplies and logistics affecting metropolitan areas in a disaster would affect hospitals. Hospitals need to have plans to mitigate damages from water and power loss and protect patients.

Danielle Hutchings Mieler, Resilience Program Coordinator for the Association of Bay Area Governments
Bridge the private and public gap in infrastructure repair:

There’s been progress in retrofitting public buildings. But many private facilities – homes, businesses and private schools – are vulnerable. This is problematic because the Bay Area is growing in areas like the shoreline, which are close to fault lines and at greater risk. Work is needed to ensure that all types of buildings – both private and public – are well prepared and sturdy.

Lewis Knight, planning and urban design practice leader, Gensler
Think different about infrastructure and retrofitting:

Many engineering firms report to Wall Street and big infrastructure. They aren’t truly considering changes that need to be made to protect communities affected by both earthquake risk and climate change. There needs to be frank discussions about how infrastructure can be part of a defense against natural disasters.

What else is crucial to consider when thinking about the next earthquake?

Infographic: When the "Big One" Hits

The Need for Preparation and Resiliency in the Bay Area

With the recent August 24, 2014 M6.0 Napa Earthquake, the San Francisco Bay Area was reminded of the importance of preparing for the next significant earthquake. The largest earthquake in recent memory in the Bay Area is the 1989 Loma Prieta earthquake. However, in the event of a future earthquake, the impacts on property and people at risk are higher than ever. Since 1989, the population of the region has grown 25 percent, along with the value of property at risk, and according to the United States Geological Survey, there is a 63 percent chance that a magnitude 6.7 or larger earthquake will hit the Bay Area in the next 30 years.

The next major earthquake could strike anywhere – and potentially closer to urban centers than the 1989 Loma Prieta event.  As part of the commemoration of the 25th anniversary of the earthquake, RMS has developed a timeline of events could unfold in a worst-case scenario event impacting the entire Bay Area region.

In the “Big One’s” Aftermath

Prepare

This black swan scenario is extreme and is meant to get the stakeholders in the earthquake risk management arena to consider long-term ramifications of very uncertain outcomes. According to RMS modeling, a likely location of the next big earthquake to impact the San Francisco Bay area is on the Hayward fault, which could reach a magnitude of 7.0. An event of this size could cause hundreds of billions of dollars of damage, with only tens of billions covered by insurance. Without significant earthquake insurance penetration to facilitate rebuilding, the recovery from a major earthquake will be significantly harder. A cluster of smaller earthquakes could also impact the area, which, sustained over months, could have serious implications for the local economy.

While the Bay Area has become more resilient to earthquake damage, we are still at risk from a significant earthquake devastating the region. Now is the time for Bay Area residents to come together to develop innovative approaches and ensure resilience in the face of the next major earthquake.

Understanding Aftershock Risk: The 10th U.S. National Conference on Earthquake Engineering

Recent earthquakes in New Zealand and Japan show that aftershock risk can be significant, even though this risk is not explicitly considered in portfolio risk assessment. It is no secret that large-magnitude earthquakes are generally followed by high numbers of smaller magnitude earthquakes and sometimes the ground motions from these aftershocks cause substantial damage to buildings. The science of forward prediction of aftershock hazard is still evolving and assessment of building vulnerability due to mainshock and aftershock sequences is currently an active topic of research.

In order to address this issue with the scientists and engineers, I organized a special session during the U.S. National Conference on Earthquake Engineering with Dr. Nicolas Luco of the USGS and Dr. Matt Gerstenberger of GNS Science. We invited a number of prominent researchers to discuss:

  • aftershock hazard
  • structural fragility/vulnerability before and after the mainshock
  • change in risk due to aftershocks

Aftershock risk is real and consumers feel the pain from increased insurance premiums, as observed following the Tohoku earthquake. According to Insurance Insight, “local earthquake premiums are up 25 percent to 50 percent, say, when compared with normal circumstances.“ So, this issue needs to be addressed to improve our understanding before another large magnitude event strikes.

Professor Fusakichi Omori first observed in 1894 that aftershocks decrease regularly with time. He developed Omori’s law, which is still used for estimating aftershock risk. I presented a paper in a separate conference session on estimation of aftershock risk in Japan following the Tohoku earthquake, which was based on the Omori Law. This is the basis of the RMS® Japan Earthquake Model update. Currently, the USGS is working on developing aftershock hazard based on the Epidemic Type Aftershock Sequences (ETAS) model.

Dr. Ned Field of the USGS, one of the speakers in the session, stated that developing the aftershock model is “one of the strategic-action priorities of the USGS in terms of providing effective situational awareness during hazardous events.”

In the meantime, GNS Science has developed a time-dependent hazard model for continuing the Canterbury earthquake sequence. Dr. Gerstenberger of GNS Science reported that GNS has carried out “broadband ground motion simulations” for a suite of moderate sized aftershocks in order to develop aftershock hazards in the region.

Dr. Luco, the co-convener of the session, proposed probabilistic risk assessment for “post-earthquake mitigation decisions” after the occurrence of mainshock (or any other earthquake).

They discussed three different approaches of aftershock hazard calculations and two approaches for estimating increased collapse probability of buildings due to aftershocks. These approaches can ultimately be synthesized to compute the increased earthquake risk of damage or collapse of buildings following earthquakes.

RMS will continue to work alongside our industry colleagues to improve understanding of aftershock risk.

Disaster Risk Reduction: Catastrophe Modeling Takes the Stage at the United Nations

The UN meeting room at the Palais de Nations in Geneva is oval shaped and more than 100 feet long with curved desks arranged in a series of “U”-shaped configurations. Behind each desk, delegates sit with their placards. On the long desk at the front, from left to right the placards read “IIASA” (a systems research institute based in Austria), “Mexico,” “Japan,” “Netherlands,” and “Risk Management Solutions.”

What was RMS doing on the podium at the UN?

Last month I presented on investing in disaster risk reduction, giving the modeler’s point of view on how risk modeling can be linked with incentivizing actions to reduce the impacts of disasters.
This was a key meeting of what was called “PrepComm,” aimed at coordinating national action for disaster risk reduction. The first such agreement, known as the Hyogo Framework for Action (the HFA), initiated in 2005, is up for renewal in 2015. The plan is to create a tougher and more tangible set of goals and procedures with demonstrable outcomes to reduce the loss of lives, livelihoods, and wealth in disasters.

In some form, catastrophe risk models or modeled outputs are required for setting and monitoring progress in disaster risk reduction. I often use the story of Haiti to make the point: fewer than ten people were killed in earthquakes in Haiti between 1900 and 2009; then in one afternoon in early 2010, an estimated 200,000 people were killed. You cannot use previous disaster data to measure future disaster risk; the underlying distribution of impacts is so skewed, so fat-tailed, and so unknown, that a decade of disaster outcomes reveals nothing about the mean risk.

The UNISDR—the influential UN agency that focuses on disaster risk—recognized the power of probabilistic modeling five years ago. However, it remains hard to communicate that to monitor progress on disaster risk reduction you will have to find some proxies for impacts, or use a model. That was the subject of my address to this session. Borrowing a quote from Michael Bloomberg, sponsor of the Risky Business study for which RMS was the modeler of all the future coastal and hurricane risks: “if you can’t measure it, you can’t manage it.”

The delegate from Algeria was skeptical about how to get the private sector involved in disaster risk reduction. I told the story of Istanbul, where the government makes deals with developers to demolish and reconstruct the most dangerous apartment buildings, rehousing the original occupants while the developer profits from selling extra apartments.

The Philippines wanted to know about empowering local authorities. My answer: get the future risk-based costs of disasters on their balance sheet.

Austria wanted to spread the idea of labeling the risk on every house. The Democratic Republic of Congo wanted to know why conflict is not considered a natural hazard. There were many questions and points of discussion over the course of the meeting.

When the next iteration of HFA arrives in a few weeks time, we will see how all the advice, debate, and consultation from the UN meeting has been digested. Regardless, when governments sign off on the new protocol in Sendai, Japan next March, catastrophe risk modeling is likely to become a core component of the global disaster risk reduction agenda.

Because as Michael Bloomberg said, “If you can’t measure it, you can’t manage it.”