Disaster in Paradise? Even the Sweetest Dreams Can Become Nightmares without Adequate Information and Preparation, Part 3 of 3
- Southeast Asia Multi-Hazard Case Study
The first two parts of this series presented some insights from the Pacific Disaster Center and the unique perspective of this quasi-government organization on disaster recovery planning. We’ve saved the best for last! Before taking the plunge and moving your business to some idyllic location (see Figure 1), how would you like to be able to compute the precise probability of a disaster there? Using information and tools provided by the PDC, it’s possible to make extraordinarily accurate estimates of the probability of disaster. And a lot of this information is free. Since you probably don’t have the server capacity to store the literally terabytes of data you’ll need to make a rational judgment (demographic, seismic, weather, topographic, oceanic, and more), organizations like this can help you out by letting you look at their data instead.
The PDC has developed the Asia Pacific Natural Hazards and Vulnerabilities Atlas, an extraordinary repository of data that can be used to examine the populations and infrastructure at risk due to natural hazards present in a given region. The Atlas provides decision makers and contingency planners like you with a resource for understanding the types, frequencies, and severities of hazards that may threaten their communities. It can play an important role in raising awareness of these hazards and their associated risks, and in helping policy makers, humanitarian assistance organizations, the international development community, and the public at large to develop potential mitigation strategies.
Southeast Asia Multi-Hazard Case Study
To show you the value of the available data for making decisions, we present a case study that illustrates how the PDC’s Atlas can be used to examine the combined risk posed by tropical cyclones and earthquakes in Southeast Asia.
Step 1: Look for Natural Hazards
We begin by examining the potential for natural hazards that can cause harm to a society’s people, infrastructure, or environment. Historical records of these events can be examined using the PDC’s Atlas. Figure 2 shows the locations and intensity of recent major earthquakes  in the Southeast Asia region. The earthquake intensity layer underlying this diagram maps (with a 20% probability) the Modified Mercalli intensity  expected to be exceeded during a 50-year period for a given location. (The 50-year period represents the average design life of a building.) For example, in Figure 2 the dark green areas correspond to intensity expectations of V and below, while orange areas have a 20% probability of experiencing an earthquake intensity of IX or higher over the next 50 years. In the most seismically active areas, the symbols representing epicenter locations almost completely obscure the underlying intensity layer at this scale.
Figure 2 Earthquake epicenters clearly outline the "Ring of Fire" along tectonic plate boundaries. The background colors correspond to earthquake intensity zones and are derived from the earthquake epicenter data.
The Zoom tools of the Atlas can be used to examine the data at a higher resolution. The Identify and Select tools can be used to view details, including magnitude and date, of recent or historical earthquake events.
Tropical cyclones can be investigated in much the same way. Figure 3 shows tropical cyclone intensity zones for the same region we’ve just discussed. The data maps areas that have a 10% probability of experiencing a tropical storm of a given intensity during a 10-year period. Darker shades of blue correspond to higher storm intensities. For example, light blue bands show areas that are expected to experience a tropical storm with maximum sustained winds of 118 to 153 km/hr, while the darkest blue areas could expect a tropical storm with maximum sustained winds over 250 km/hr.
Figure 3 Tropical storm intensity zones estimate the most severe storm that a region is expected to experience during a 10-year period based on analysis of historical storm data. Tropical storm Inigo, active at the time this graphic was captured (April 2003), can be seen off the western coast of Australia.
Now let’s take this data and compare it to the critical infrastructure located around our proposed business. Using the PDC’s tools, the relationship between these hazards and potentially impacted resources can be observed by displaying the hazards along with population centers, roads, railroads, and airports. Figure 4 shows the earthquake risks, along with transportation infrastructure, for a portion of the Philippines including Manila. Figure 5 shows tropical storm risks for the same area.
Figure 4 The frequency and severity of earthquakes in and around Manila places much of the region in the top two categories of earthquake intensity. Most of metropolitan Manila can expect an earthquake of intensity VIII or higher once per 50-year period (with a 20% probability), while the remaining eastern region can expect earthquakes with even higher intensity (IX) during the same timeframe.
Figure 5 By analytically combining both the Earthquake Hazard Index and the Tropical Storm Hazard Index into a Multi-Hazard Index, the patterns are made even more evident and, more importantly, can be used to assess hazard exposure to various categories of human and natural resources.
As Figure 4 shows, this area is frequented by tropical storms, and falls within the top end of the storm intensity zones. By creating a virtual overlay of earthquake and tropical storm risks (see Figure 6), it’s possible to draw some conclusions about the potential natural hazards to human populations (see Figure 7).
Figure 6 Some regions, such as the western portion of Borneo, face relatively low risk; others, such as the Philippines, face a high risk of both earthquakes and tropical storms.
Figure 7 Southeast Asian countries have some of the highest population densities in the world. Indonesia, for example, is the fourth most populous country (behind only China, India, and the U.S.), but has less than one quarter of the land area of the U.S.
Step 2: Analyze Potential Exposure to Hazards
The next step in the multi-hazard risk assessment process is to analyze the varying degree of potential exposure of people and infrastructure to the hazards present in a region. The Atlas contains data layers for both population density and transportation infrastructure (roads, railroads, airports). By combining population density (see Figure 8) with transportation infrastructure (see Figure 9), we can examine the relative magnitude (or density) of people and infrastructure exposed to potential harm from future occurrences of earthquakes and tropical storms.
Figure 8 Population density around the proposed business location.
Figure 9 Transportation and infrastructure—including roads, railroads, and airports—are subject to exposure to natural hazards as well as key to a region’s recovery following such an event. The PDC’s Atlas supports assessment of the vulnerability of these critical assets to various hazards. Here this data is superimposed over the population density data.
Step 3: Identify High Impact Potential
Finally, the categorized population density data, along with the transportation infrastructure data, are combined analytically with the multi-hazard index to identify those areas with a high potential for impact from these natural hazards (see Figure 10).
Figure 10 Areas with a high hazard index and a high number of people and infrastructure systems would warrant the most attention from mitigation efforts, as well as be expected to require significant resources during the response and recovery phases of a natural disaster.