Category Archives: Typhoon

China Reinsurance: Domestic or Global Expansion Both Require Risk Modeling

Paul Burgess, Client Director, Asia-Pacific, RMS

Erica Xue, Senior Product Manager – Model Development, RMS

In a country that according to the United Nations, between 1995 and 2015 experienced the largest number of natural disasters globally, and with these losses largely uninsured, China is at the start of a journey to close its protection gap between economic and insured losses — during a sustained period of rapid GDP growth. Examples such as the devastating Sichuan earthquake in 2008 which killed more than 80,000 people and caused US$125 billion in economic losses saw just 0.3 percent of losses covered by insurance. Floods in southern China during the summer of 2016 saw economic losses of US$20 billion, the second costliest event of the year. But again, according to Munich Re, just two per cent was insured.

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Covering All Bases: Modeling Typhoon and Non-Typhoon Driven Flood in the Philippines

In a country that is used to the regular rhythm of typhoon seasons, 2017 disrupted the pattern and was a surprisingly quiet year in terms of landfalling typhoons in the Philippines. While 26 named storms formed in the western North Pacific basin, equaling the long-term average, all other tropical cyclone statistics fell below the 1981-2010 average. Only 12 of these named storms developed into typhoons, and just four reached a strength of category 3 or above on the Saffir-Simpson scale. No typhoons made landfall in the Philippines during the year for only the fifth time in recorded history.

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Asia’s Costliest Cyclones: The Curse of September

The northwest Pacific is the most active tropical cyclone basin in the world, having produced some of the most intense and costly cyclone events on record. The 2015 typhoon season has been particularly active due to this year’s strong El Niño conditions.


Sea surface temperature in the equatorial Pacific Ocean. El Niño is characterized by unusually warm temperatures in the equatorial Pacific. (NOAA)

The unpredictable nature of the El Niño phenomenon, which affects the genesis and pathway of tropical cyclones, and the complexity of tropical cyclone systems underscore the need to fully understand typhoon risk—particularly in Japan where exposure concentrations are high. Catastrophe models, such as the forthcoming RMS® Japan Typhoon Model, using a basin-wide event set to model the three key correlated perils—wind, inland and coastal flood—are more effective in enabling firms to price and manage the ever-evolving exposures that are at risk from this multifaceted peril.

The Significance of September

Peak typhoon season in the northwest Pacific basin is between July and October, but it’s September that typically sees the highest number of strong category 3-5 typhoons making landfall: eight of the top ten greatest insured losses from northwest Pacific tropical cyclones since 1980 all occurred in September.

In September, during El Niño years, Guam is significantly more susceptible to a higher proportion of landfalls, and Japan and Taiwan experience a slight increase due to the genesis and pathway of tropical cyclones. While wind is the primary driver of tropical cyclone loss in Japan, inland and coastal flooding also contribute substantially to the loss.

In September 1999, Typhoon Bart caused $3.5 billion in insured losses due to strong winds, heavy rainfall, and one of the highest storm surges on record at the time. The height of the storm surge reached 3.5 meters in Yatushiro Bay, western Japan, and destroyed coastal defences, inundating vast areas of land.

Five years later in September 2004, Typhoon Songda caused insured losses of $4.7 billion. Much of the loss was caused by rain-related events and flooding of more than 10,000 homes across South Korea and Japan in the Chugoku region, western Honshu.

Table 1 Top 10 Costliest Tropical Storms in Asia (1980-2014):

Date Event Affected Area Maximum Strength (SSHWS) Insured Loss ($mn)
Sept, 1991 Mireille Japan Cat 4 6,000
Sept, 2004 Songda Japan, South Korea Cat 4 4,700
Sept, 1999 Bart Japan, South Korea Cat 5 3,500
Sept, 1998 Vicki Japan, Philippines Cat 2 1,600
Oct, 2004 Tokage Japan Cat 4 1,300
Sept 2011 Roke Japan Cat 4 1,200
Aug – Sept, 2004 Chaba Japan, Russia Cat 5 1,200
Sept, 2006 Shanshan Japan, South Korea Cat 4 1,200
Sept, 2000 Saomai Japan, South Korea, Guam, Russia Cat 5 1,100
Sept, 1993 Yancy Japan Cat 4 980

Munich Re

September 2015 – A Costly Landfall for Japan?

This September we have already seen Tropical Storm Etau, which brought heavy rains to Aichi Prefecture on Honshu Island causing immense flooding to more than 16,000 buildings, and triggered dozens of landslides and mudslides.

The increased tropical cyclone activity in the northwest Pacific this year has been attributed to an El Niño event that is forecast to strengthen further. Two factors linked to El Niño events suggest that this September could still see a costly landfall in Japan:

  • El Nino conditions drive the formation of tropical cyclones further eastward, increasing the travel times and distances of typhoons over water, giving rise to more intense events.
  • More northward recurving of storms produces tropical cyclones that track towards Japan, increasing the number of typhoons that could make landfall.

Combined, the above conditions increase the number of strong typhoons that make landfall in Japan.

Damaging Typhoons Don’t Just Occur In September

Damaging typhoons don’t just occur in September or El Niño years – they can happen under any conditions.

Of the ten costliest events, only Typhoon Mireille in 1999 and Typhoons Songda, Chaba, and Tokage, all of which made landfall in 2004, occurred during El Niño years

Look out for more information on this topic in the RMS paper “Effects of the El Niño Southern Oscillation on Typhoon Landfalls in the Northwest Pacific”, due to be published in October.

The 2015 Northwest Pacific Typhoon Season: Already a Record-Breaker

While the Atlantic hurricane season is expected to be below average this year, the North Pacific is smashing records. Fuelled by the strengthening El Niño conditions, the Accumulated Cyclone Energy (ACE)—used to determine how active a season is by measuring the number of storms, their duration and their intensity—continues to set unprecedented highs for the 2015 season.  According to Dr. Philip Klotzbach, a meteorologist at Colorado State University, the North Pacific ACE is 30% higher for this time of year than at any other time since 1971.

Philip J. Klotzbach, Colorado State University

To date, there have been 12 named Northwest Pacific storms, of which three have strengthened to Category 5 super-typhoon status, and two have strengthened to Category 4 typhoon. Typhoon Maysak was the first of the super-typhoons to develop and is reportedly the strongest known storm to develop so early in the season—it eventually passed over the northern Philippines in late March as a tropical depression. Super-Typhoons Noul and Dolphin followed in quick succession in May, with Noul scraping the northern tip of the Philippines, and Dolphin tracking directly in-between the islands of Guam and Rota.

China is recuperating after getting hit by Typhoons Linfa and Chan-Hom only days apart. Linfa made landfall on July 9, bringing strong winds and heavy rainfall to Hong Kong and southern China’s Guangdong province. Two days later, Chan-Hom brought tropical storm-force winds and heavy rainfall to Taiwan and the Japanese Ryukyu Islands before briefly making landfall as a weak Category 2 storm over the island of Zhujiajian in the Zhejiang province. Prior to landfall, Chan-Hom was anticipated to pass over Shanghai, but swung northeast and missed China’s largest city by 95 miles. Despite this near-miss, Chan-Hom still stands as one of the strongest typhoon to have passed within 100 miles of the city in the past 35 years.

Typhoon Nangka, the first typhoon to hit Japan this season, intensified to a Category 4 storm before ultimately making landfall as a Category 1 storm over the Kochi Prefecture on Shikoku Island, Japan. Although Nangka’s strength at landfall was weaker than originally forecast, the high level of moisture within the system caused significant rainfall accumulations, leading to widespread flooding and the threat of landslides. While there was an initial fear of storm surge in Osaka Bay, there has been limited damage reported.

This record-breaking season has been strongly influenced by the strengthening El Niño conditions, which can be characterised by several physical factors including warmer sea surface temperatures, a higher number of Category 3-5 typhoons, and a greater proportion of typhoons that follow recurring or northward tracks—all of which have been evident so far this year.

With El Niño conditions expected to continue intensifying the storms to come, this season highlights the necessity for a basin-wide multi-peril model, connected through an event-based approach and correlated geographically through a basin-wide track set. These will be featured in the new Japan typhoon model, due out next year, followed by the South Korea and Taiwan typhoon models. The RMS China typhoon models currently models typhoon wind, inland flood and surge for a correlated view of risk.

As El Niño conditions continue to bolster the Northwest Pacific typhoon season, RMS will be monitoring the situation closely. In September, RMS will be releasing a white paper on ENSO in the West Pacific that will provide further insight into its affects.

Rammasun is One of the Strongest Typhoons to Hit Southeast China in Recent Years

RMS closely monitored typhoon Rammasun last week as it picked up strength en route to the Philippines. The world also watched, remembering the catastrophic damage typhoon Haiyan caused last November. While Rammasun did not wreak as much havoc as Haiyan, it still left a trail of damaged buildings and flooded crop fields in the Phillipines, southeast China and Vietnam. Below, RMS looks at the property damage and insurance industry implications as the typhoon hit both denser commercial metropolitan areas and agricultural provinces.

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RMS reports that on Friday, July 19 Super typhoon Rammasun, one of the strongest to hit southeast China in recent years, made three landfalls in the provinces of Hainan, Guangdong, and Guangxi.

Rammasun has significantly impacted the Philippines, southeast China and Vietnam. Rammasun brought strong winds, heavy rain, and storm surge to some coastal areas with close to 300,000 buildings damaged in the affected countries.

In China, damaging wind and floods have destroyed at least 37,000 homes and ravaged 468,500 hectares of crops in Hainan, Guangdong and Guangxi provinces. Virtually all brick-and-tile houses in the town of Wengtian, Hainan were either destroyed or had their roofs removed. Within a 24 hour period up to 15 inches of rain fell in the city of Haikou; the week before Rammasun hit, the southeastern provinces were reportedly experiencing heavy floods, which have only been exacerbated by the typhoon.

“Typhoon-related flood, which includes both rainfall driven and coastal flooding, contributes as much as 80% to typhoon average annual loss in China, with the coastal provinces driving the loss,” said Nikki Chambers, hazards scientist at RMS. “July to October are the most active months for typhoons in this region. On average 6 typhoons make landfall a year in China and typhoon Rammasun highlights the importance of accounting for all sources of typhoon losses, of which flood is the main driver.” Insurance penetration is extremely low in China particularly for residential risk, slightly higher for commercial and industrial lines of business. On average, about 15% of property risk in China is insured. Insurance penetration varies by province; Hainan has one of the lowest insurance penetrations in China. Guangdong is one of the more prosperous provinces; it is the second largest province for property insurance purchases, with 41.7 billion yuan (US$6.8 billion) in direct premiums for property insurance in 2012, according to the China Insurance Regulatory Commission.

Philippines

The typhoon wreaked havoc earlier in the week in the northern Philippines, which is still rebuilding after Typhoon Haiyan. Rammasun made its first landfall in the largely agricultural provinces south of the capitol Manila, leaving 94 people dead, and over 111,000 houses damaged, of which nearly 28,000 have been totally destroyed and 83,000 have been partially damaged., Based on analysis from the RMS Philippines Economic Exposure Database, the impacted provinces in the Philippines from Rammasun contains over 100 bn USD of insurable commercial building exposure, 80 bn USD of industrial building insurable exposure, and over 215bn USD of residential building exposure. Based on the RMS Philippines industrial cluster catalog, industry is clustered around metro Manila and in areas to the north and south of the capital in Central Luzon, which are located within the affected area of Rammasun. The insurance penetration rates in the Philippines is relatively low, though higher for commercial and industrial lines of business and will be centred around Manila and the industrial zones.

Vietnam

In northern Vietnam, Typhoon Rammasun made landfall Saturday morning, causing heavy flooding. At least eight people have died and it has affected more than 6,000 homes. The typhoon has damaged 3,300 hectares of rice and other crops and disrupted traffic in the region. Typhoon, Matmo, with maximum winds of 150km/h, is now threatening the area ravaged by Rammasun. RMS is monitoring the situation closely.

The Dangerous City of Tacloban

The city of Tacloban, on the island of Leyte, is the largest city in the eastern Visayas region of the central Philippines. In a 2010 survey by the Asian Institute of Management, Tacloban was ranked fifth in the “most competitive” cities in the Philippines, and second in the class of “emerging cities.” Before Haiyan’s storm surge, the city was thriving, with only one third the national average poverty levels.

However, from the natural hazards perspective Tacloban would also be high up on a list of the most dangerous medium size cities in the world.

Tacloban faces east into the tropical Pacific where there is the largest, deepest and hottest pool of ocean water on the planet, fuel for cooking up intense super typhoons, and sustaining their intensity all the way to landfall. More significantly the port city is located in the apex (or “armpit”) of a funnel-shaped coastline – where the eastern coast of the island of Leyte meets the southern coast of the island of Samar. Although the 2km wide “San Juanico” channel separates these islands, in a fast westerly moving typhoon, this channel cannot relieve the large dome of water pushed ahead of the storm.

Funnel shaped coastlines are notorious for concentrating and amplifying tropical cyclone storm surges. New York City is situated at the apex of the funnel-shaped coastline where New Jersey meets Long Island, amplifying the surge from Super-storm Sandy. Osaka in Japan is also at the apex of funnel coastline. However intense typhoons pass close to Leyte far more often than intense hurricanes come to New York or Japan.

The ground on which the quarter of a million population city of Tacloban has grown up is remarkably flat and only a meter or two above high tide level. A 4-6 meter storm surge and its accompanying waves can penetrate far inland, ripping houses off their foundations for several blocks, just as happened in the cities along the southern coast of the State of Mississippi in Hurricane Katrina.

Tacloban is built on a former wave-cut platform, at the foot of active cliffs, which has become raised out of the sea by active tectonics. For the city is also located in the frontline of a plate boundary.

Offshore to the east, less than 80km from the neighbouring island of Samar, a deep sea trench, marks where the Philippines Sea plate moves down beneath the Philippines, at around 50mm per year. The 1300 km NNW-SSE Philippines subduction zone appears to be locked, and has not broken in a major earthquake through the past four hundred years, since the start of Spanish colonial rule.

If, as is suspected, the Philippines subduction zone is capable of generating a giant Mw9 earthquake, then this will be accompanied by a large tsunami, as in Sumatra 2004 and Tohoku, Japan in 2011. Tacloban is very much in the frontline of such a tsunami – the biggest city, on low ground, facing the open Pacific. A tsunami at 10 m or more could cause more casualties and destruction even than the 2013 storm surge.

Tacloban city was founded as a fishing village and more recently achieved fame as the birthplace of Imelda Marcos. Some parts of its history are obscure, in particular when it first became a municipality, as the records were all destroyed in a previous typhoon. The name Tacloban has the potential to recur on the list of future catastrophes. Only action in reconstruction, relocating the city away from the low lying coast, can reduce that potential.

Life Safety on a Cat 5 Coastline

Many of the thousands of lives lost in Super Typhoon Haiyan could have been saved if a proper storm surge forecast had been provided, and if that forecast had been turned into effective evacuations moving people to buildings inland out of reach of the surge.

The civil defense personnel were there on the ground and Philippines has a sophisticated system of disaster management. The civil defense personnel had been told to ensure zero casualties, but had not been given the information by which to achieve this goal. In previous storms lives had been lost in flash flooding and landslides, but Haiyan was moving fast, and rainfall was not a principal hazard.

The Category 5 storm was well forecasted in the days and hours leading up to landfall. Knowing the structure of the advancing wind field, the height and extent of the accompanying storm surge could also have been forecasted. If people had been moved out of the surge zone, that would have significantly increased their chances of survival, but even then they would need protection from collapsing buildings and missiles propelled by the extreme wind speeds.

Maybe people who lived in low lying coastal areas on Leyte may have been lulled by what happened the last time a Super Typhoon (named Mike) was heading towards their island in 1990 when it weakened significantly in the hours before landfall.

Even on the most active Category 5 coastlines, as those of the eastern Philippines, extreme storms are still relatively rare and it is all too easy to forget the threat they bring. Houses that provided protection in lesser storms may prove highly vulnerable in a Category 5 cyclone and its accompanying storm surge.

Super-Typhoon Haiyan is not the first Category 5 cyclone to cause devastation to an island community. Something similar to Haiyan in Leyte happened on October 10, 1780 when an intense Category 5 hurricane hit Barbados. The winds stripped the bark off trees and were said to have left no tree standing (interpreted as reflecting winds over 200 mph). “Every house on the island” was destroyed as well as all the military forts. On one such fort the wind carried a heavy cannon for 30 meters. Many people took refuge in the stone churches on the island, but almost all of these were destroyed by the wind. The final death toll on Barbados was 4,500. The storm continued on its track to spread destruction through St. Lucia, Martinique, and Guadeloupe.

Following the Haiyan disaster, a series of international actions are now needed with a focus on ensuring life safety:

  1. Identify all those coastlines with the potential to be hit by Category 5 tropical cyclones. To gain this intensity requires both very warm sea surface temperatures (SSTs) and a deep thermocline (layer of warm near-surface water), as otherwise the winds and waves from the storm draw cooler waters to the surface and switch off the circulation. The region with the highest SSTs and deepest thermocline is the Pacific immediately to the west of the Philippines. However many tropical and subtropical coastlines can expect to see occasional Category 5 storms: in the Atlantic this includes most of the islands of the Caribbean, the Atlantic Coast of Mexico, the coastlines of Florida and the Gulf and southeast U.S.
  2. For each coastline, work is required to map the maximum potential storm surge flood height, associated with the most extreme credible storms. This will require building a stochastic tropical cyclone event set, with a focus on the most extreme events and running it with a coupled ocean-atmosphere storm surge model. These flood heights will likely be much higher than the typical 100 year return-period flood heights, used for flood insurance in the U.S., for example. This “maximum storm surge flood extent” should be publicized on local maps. For an intense storm no one should be permitted to stay in their property if it lies within the maximum flood extent.
  3. Evacuation options should be evaluated, according to the number of people living in the maximum flood zone. For continental coastlines, evacuation inland will be the preferred option, but there are particular challenges for coastal cities and small islands. As highlighted by Hurricane Katrina and New Orleans, preparations should be made to protect those who choose to stay.
  4. Where evacuation is not a complete option, hardened shelters need to be provided, guaranteed to survive the strongest possible winds in a tropical cyclone, and situated above the maximum potential flood extent. These shelters need to have enough accommodation to house all the local population for the few hours in which it takes the storm to pass, as well as containing water and food for at least 2-3 days. These shelters could be in the basements of community centers, businesses or hotels. Shelters could also be constructed in basements beneath houses, exactly as in tornado country. As reconstruction gets underway in the Philippines, international donors should insist that among the replacement buildings there are enough that could also act as future Super Typhoon shelters. Otherwise the conditions will be created for a repeat of this catastrophe sometime in the future.

Category 5 cyclones bring a range of perils—wind, surge and flash flooding. It is particularly dangerous to focus on only one peril at a time. People sheltering from the winds of Super Typhoon Bopha in the southern island of Mindanao less than a year ago were drowned by flash floods. On the south coast of the main Bahamas island of New Providence, I once found a school labeled as a designated hurricane evacuation center, but situated only 2–3 feet above sea level.

Haiyan has highlighted that Category 5 cyclones can present some special challenges. However, given our understanding of disaster management and what can be forecasted and delivered there is now really no excuse for having high casualties in a landfalling tropical cyclone anywhere in the world.