Category Archives: Earthquake

The Problem of Real and Unreal Tsunamis

Indonesia was beset by disasters in 2018, including two high casualty local tsunamis: in coastal western Sulawesi – impacting the city of Palu, on September 28, and around the Sunda Strait, between Java and Sumatra, on December 22. These events may have appeared unusual, but the great subduction zone tsunamis, like those in the Indian Ocean in 2004 and Japan in 2011, have reset our imagination. Before 2004, forty years had passed without any transoceanic tsunamis. Overall, local tsunamis are more common, presenting many challenges in how they can be anticipated.

The Palu tsunami reminds us how “strike-slip” faults, involving only horizontal displacement can still generate tsunamis, first as a result of vertical displacement at “jogs”, where the fault rupture jumps alignment, as well as from triggered submarine landslides. It seems both factors were important in driving the Sulawesi tsunami that became amplified to more than four meters (13 feet) in the funnel-shaped Palu embayment.

The December 22 Sunda Strait tsunami was caused by a submarine landslide on the erupting Anak Krakatoa volcano and arrived without warning, in the dark of mid-evening. More than 400 people drowned mainly around a series of beach resorts in Banten and Lampung provinces, although water levels in the tsunami only reached a meter or two above sea level. An audience of 200 enjoying a concert at the Tanjung Lesung Beach Resort, staged directly on the beach by Indonesian rock band Seventeen were caught unaware. 29 concertgoers were killed together with four people associated with the band.

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De-risking the City

I am in Wellington, New Zealand, looking out from a rainy hotel window high over the city, admiring the older wooden houses on the forested slopes. Below there are four to eight story office and retail buildings, a number of which are shrouded in scaffolding, still repairing damage from the 2016 Kaikoura earthquake. The earthquake epicenter was some distance from the city, but the pattern of fault ruptures propelled long period ground shaking into the heart of Wellington.

In 1848, only eight years after the city was founded, a Mw7.5 earthquake on the far side of Cook Strait, shattered the town’s brick buildings. The Lieutenant Governor, Edward Eyre, forgetting his official role as colonial booster, declared the “… town of Wellington is in ruins … Terror and despair reign everywhere. Ships now in port … (are) crowded to excess with colonists abandoning the country.” However, the tremors declined, and the town survived.

Many ordinary houses were rebuilt using wood instead of brick. As a result, they suffered far less damage from a larger and closer Mw8.2 earthquake in 1855, that struck at the end of a two-day public holiday to celebrate the fifteenth anniversary of the city’s formation. This ruined all the remaining brick and stone commercial buildings including churches, barracks, the jail, and the colonial hospital. However, the earthquake delivered a tectonic bounty, raising the city by one to two meters (3.2 to 6.5 feet), turning the harbor into new land for development.

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RMS Impact Trek: Share Your Expertise and Make a Difference

Many of us across the risk management industry actively help communities in need after natural disasters, through donations, working with organizations to promote resilience, or through on-the-ground assistance. Our intimate understanding of the power of these catastrophes makes us acutely aware of the need to act.

This is true for everyone here at RMS, where our values embrace the need to understand risk, build resiliency, and make an impact to help improve the lives of communities who live with the threat of natural disasters. One of the ways we live our values is through our annual RMS Impact Trek, where both RMS employees and our clients work with the social enterprise Build Change in some of the world’s most catastrophe-prone areas.

If you are an RMS client, I would like to extend an invitation to our annual RMS Impact Trek. This is the fourth year that we are sponsoring representatives from our clients to join RMS employees and Build Change so that their skills can be used to build stronger communities.

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From Farmer to Finance Minister

When I was still a teenager – summer brave, full of sport, hot and bold – I hitchhiked from Lithuania to Armenia and back again. Outbound via the former Soviet Union and the Caucasus; home via Turkey and the Balkans.

Time rich and cash poor, I took risks I wouldn’t today. All the same, my gambles paid off and I look back on that adventure fondly.

The journey was filled with comparisons and contrasts. Some things, like being invited in basic Russian to squeeze into a crammed Lada Riva, remained almost constant from country to country. Others, like the landscapes and local delicacies, evolved with every new ride.

When I found myself back in Istanbul last month for the first time since my hitchhiking days, I was again struck by these contrasts. Here I was, a guest of the United Nations, discussing disaster risk reduction financing with the finance ministers of those countries through which I’d once hitchhiked. And here I was, marveling afresh at the cultural, political, economic and geographical diversity of a vast region which yet shares so much.

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The Lessons From “Last Year’s” Catastrophes

Catastrophe modeling remains work in progress. With each upgrade we aim to build a better model, employing expanded data sets for hazard calibration, longer simulation runs, more detailed exposure data, and higher resolution digital terrain models (DTMs).

Yet the principal way that the catastrophe model “learns” still comes from the experience of actual disasters. What elements, or impacts, were previously not fully appreciated? What loss pattern is new? How do actual claims relate to the severity of the hazard, or change with time through shifts in the claiming process?

After a particularly catastrophic season we give presentations around ”the lessons from last year’s catastrophes.” We should make it a practice, a few years later, to recount how those lessons became implemented in the models.

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How to Maintain Awareness of Tsunami Risk

Today is World Tsunami Awareness Day — designated by the United Nations General Assembly, and according to the United Nations Office for Disaster Risk Reduction (UNISDR), on average, tsunami events have a higher mortality rate than any other hazard. Over the past 20 years (1998-2017) tsunamis have claimed more than 250,000 lives and are also attributable for US$280 billion of the US$661 billion of total recorded economic losses for earthquakes and tsunamis. Between 1978-1997, tsunamis claimed 998 lives, and US$2.7 billion in losses. Overall, tsunamis are rare, but as the UN points out, when they occur they are deadly and hugely damaging. This infrequency makes building awareness and preparedness more of a challenge.

The UN has promoted World Tsunami Awareness Day since 2015, and the UN Secretary-General’s Special Representative for Disaster Risk Reduction, Mami Mizutori, stated that “…it is an occasion to promote greater understanding of tsunami risk to avoid future loss of life. This year we also want to bring attention to the economic losses tsunamis can inflict as a result of damage to critical infrastructure located along vulnerable, densely populated coastlines.”

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Australia Earthquake Hazard: Now Reduced by Up to Seventy Percent

On October 18, 2018, Geoscience Australia (GA) released its latest view of earthquake hazard for Australia. A headline finding from the 2018 National Seismic Hazard Assessment (NSHA2018) is the reduction of the 475-year peak ground acceleration hazard estimates on rock conditions by up to 70 percent. While GA had updated the Australian seismic hazard model in 2012 (Burbidge et al., 2012), the basis of the Australia building code is a 1991 map described by McCue (1993) which is included in the Global Seismic Hazard Map (figure 1 below) published nearly twenty years ago (Global Seismic Hazard Assessment Program (GSHAP); Giardini, 1999). This 2018 update is pivotal in addressing the long running scientific debate started since.

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An Award-Winning Approach to Risk Modeling for North America

As an organization, it is always great to get recognition from the industry for the work that you are doing; and industry recognition does make a real difference to the teams that work so hard to produce robust, quality solutions that are solving the problems that the market faces. And so, on September 27, off we went to Cipriani 25 on Broadway in New York, for the Eleventh Reactions Annual North America Awards, with RMS receiving the “2018 North America Risk Modeler of the Year” award.

This award is decided by votes from the industry and it recognizes our reputation for providing best-in-class support and leadership to our North America clients, and especially at times when insight is so critical to a business — such as during the significant cat events that ran through 2017. It also provides an endorsement for the approach that RMS is taking more generally to anticipate and deliver on the needs of the North America market, to keep pushing the boundaries and break new ground, to help a growing client base across the industry ranging from reinsurers and carriers through to capital markets.

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Ultra-liquefaction Changes Everything

It turns out the biggest killer in the Palu earthquake on the island of Sulawesi, Indonesia, may not have been the tsunami after all — but liquefaction. Two thousand victims of the earthquake and tsunami are confirmed but 5,000 people remain missing, many of them presumed swallowed up in extraordinary ground deformation and mudflows, which took off when the underlying solid ground liquefied. Some buildings were transported hundreds of meters, others were ripped apart, many collapsed into fragments that then became absorbed into the mud. Media reports state that in Balaroa, just a few kilometers from Palu City, many of the 1,747 houses in the village appear to have sunk into the earth. In Petobo, a village to the east of Palu, many of the village’s 744 houses have disappeared.

What we have witnessed at Palu merits the term “ultra-liquefaction”, as witnessed in the 2011 Christchurch, New Zealand earthquake when perhaps half the total insurance loss costs were a consequence of liquefaction. For Christchurch, in the eastern suburbs it was single storey houses, ripped apart by the ground movements. In the Central Business District (CBD), many mid-rise buildings had to be demolished because underlying liquefaction had led to one corner of the structure sinking by ten or twenty centimeters (four to eight inches).

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The Tragedy at Palu

A version of this article was originally published in Insurance Day

The Mw7.5 earthquake in Sulawesi, Indonesia on September 28 reminds us that fourteen years after the terrible Indian Ocean tsunami, and despite significant investment in systems intended to provide tsunami warnings, the risk to life and property is not going away. To understand why the destruction and loss of life in the city of Palu, with a population of 350,000, is so great (1,300 and rising) we need to understand why this location has proved such a nexus of vulnerabilities.

First, Palu is located less than one degree south of the equator. That means it is in the “shadow zone” for tropical cyclones. In most of the world’s oceans, no tropical cyclone can exist within ten degrees of the equator, although in the western Pacific the typhoon exclusion zone can narrow down to six to eight degrees from the equator. The lack of Coriolis force at the equator prevents a collection of thunderstorms gaining a structured rotation (and tropical cyclones spin in opposite directions in the northern and southern hemispheres).

The lack of tropical cyclones means there are no significant storm surges, or even much in the way of significant wind-driven waves, and as a result people build their houses right down to sea level. This means, in comparison even with a coastal city in Philippines or China, there were many more seafront buildings exposed to a tsunami that reached no more than three to five meters above sea level.

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