BRIDGES – Fall 2002 Annual Report

by Ron A. Harris, professor of geology, BYU, and Prasetyadi, professor of geology, University Pembangunan Nasional, UPN “Veteran,” Indonesia


The densely populated archipelago of Indonesia—with a population of over 200 million—has more explosive volcanoes, major earthquakes, and destructive tsunamis than any other nation. These natural hazards resulted in 200,000 fatalities in the nineteenth century alone, and the societal and economic harm caused by such events is astronomical. Fortunately, such devastation can be reduced by focusing mitigation efforts on the most vulnerable parts of the country. These areas of greatest risk are identified using scientific methods that forecast where energy building up under the earth’s surface is most likely to be released. As the economy and population of Indonesia rapidly expands, a frightening disregard for geological hazards needs to be remedied to prevent even greater casualties from happening.

Which areas are most at risk?
In Western Indonesia, specifically the island of Sumatra, there is enough energy built up that an earthquake of greater than magnitude 8.0 could flatten any of seven major cities (cities with populations greater than one million) as well as many other highly populated communities. In Java, the wealthiest and most populous island in Indonesia, there is a far greater frequency of more moderate events that threaten not only most of Indonesia’s wealth and foreign investment, but over eight times as many people as live in Sumatra as well. In the rapidly developing islands of eastern Indonesia there are also signs that large events have occurred in the past that could potentially recur soon, leading to immense damage and loss of life.

Population density of Indonesia.Same map as top with explosive volcanoes (black) and earthquakes during last 60 years (green – shallow, yellow – intermediate, red – deep).

Why are earthquakes so devastating?
Earthquakes are the most poorly understood and unpredictable of all natural hazards, and Indonesia has experienced hundreds of massive ones in the last hundred years. Poorly regulated development makes matters worse, especially as the most commonly used method of construction is to build houses out of poorly formed or deformed bricks cemented together with soft mortar. When the ground shifts horizontally in a large earthquake these structures collapse, causing immediate casualties and secondary disasters related to large scale homelessness, broken water pipes, and economic devastation.
How dangerous are volcanoes?
Volcanoes are also prevalent in Indonesia. There are over five hundred there, 129 of which have erupted in recorded history. In fact, 70% of volcanic-related fatalities worldwide happen in Indonesia. Volcanoes are highly unpredictable, and it is common for supposedly “dormant” volcanoes to erupt in catastrophic and fatal ways; It is almost certain another such eruption will occur this century. Effects of such events can cause damage hundreds of kilometres away, and so zoning in an effort to avoid a volcano’s blast radius alone is insufficient.
How can these natural hazards be understood and communicated?
To display what areas are most at risk total hazard maps have been created. These maps display each type of natural hazard and its impact radius such that different hazards overlap and give a comprehensive representation of risk. By using the information in these maps, particularly in Java and Sumatra because of their high populations, it’s possible to help prepare the communities most at risk for the advent of natural disasters. Such preparation is done through site-specific risk assessment, detailed monitoring, emergency planning, and the implementation of protective zoning and building practices.
Why not just focus on disaster relief?
Disaster mitigation has implications which are quite different—and much further-reaching—than those of disaster relief. . . . Mitigation aims to increase the self-reliance of people in hazard-prone environments, to demonstrate that they have the resources and organization to withstand the worst effects of the hazards to which they are vulnerable. In other words, disaster mitigation—in contrast to dependency creating relief—is empowering.

-Boyden and David

This is our great opportunity.
Natural disaster reduction efforts offer an unprecedented opportunity to integrate systems of knowledge, technology, and public policy to minimize losses in regions of high risk. It challenges scientists to work together with the engineering sector, media, policy makers, and vulnerable communities to achieve implementation. In the past these people have worked separately towards a similar end goal—now they need to work together.

See original article: 2002 BridgesFall02