Geologists warn Sumatran coastal towns ill-prepared for earthquakes
Updated
Indonesia has cancelled a tsunami warning issued after a powerful earthquake off the north-eastern tip of Sulawesi.
There've been no reports of damage or injuries but Indonesian geologists this week warned authorities that some coastal towns on Sumatra island are ill-prepared for earthquakes. They say the city of Padang, with a population of 900-thousand, may be particularly vulnerable, as it's located in what's known as a 'seismic hot spot'. An earthquake measuring 9.15 north-west of Sumatra island, caused the 2004 tsunami, which killed 232-thousand people in Asia.
Presenter: Sen Lam
Speaker: Dr John Schneider is head of risk and impact analysis at Geosciences Australia, in Canberra
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SCHNEIDER: The entire coast of Indonesia, in particular Sumatra and Java, are exposed to essentially a plate boundary, which the Australian plate, with Australia riding upon it is moving north towards Indonesia at a rate of about seven centimetres per year, and that collision zone right off the coast of Indonesia represents the major source of earthquakes and tsunamis for the region.
LAM: Indonesian geologists this week pointed out that Padang on Sumatra Island was a particularly vulnerable spot. In geological terms, what makes Padang so vulnerable?
SCHNEIDER: Padang sits right on the coast, it's low-lying, it has a large exposed population, near a million people as I understand it. Most of that population is only at or just above or a few metres above sea level. The earthquake risk is large as a function of the combination of the population living in a low-lying area and the potential for large earthquakes off the coast. And those large earthquakes, a magnitude eight or so, earthquakes which could occur there have the significant potential to generate large tsunami waves.
LAM: Indeed as you say Padang because it's low-lying, there's not high ground for people to run to should a tsunami occur. The 2004 tsunami of course gave tsunamis a global awareness and notoriety, but are people killed more often by falling buildings rather than a tsunami when an earthquake hits?
SCHNEIDER: Oh, worldwide certainly. The largest source of fatalities and indeed economic loss or physical damage from earthquakes is from earthquakes shaking and ensuing damage of infrastructure. However, tsunamis which are generally caused by earthquakes, are of particular risk for coastal communities where you have these large earthquakes, at these plate boundaries where you have large earthquakes occurring basically under the sea, those can generate large waves and then impact coastal communities severely. They also have the potential to affect a very large area because these ocean waves can propagate quite far without dissipating very much energy.
LAM: And given that Indonesia faces this constant threat, just how prepared do you think are local authorities?
SCHNEIDER: I know there's been considerable work done in the last several years - certainly since the 2004 tsunami. And the Indonesian government has been working very closely with a number of other governments as well as other, a wide variety of agencies, UN agencies, non-government organisations et cetera, that have been working very hard to assist Indonesia. Padang has been identified as an area of very high risk, in particular. I know the German government, who has been assisting them with developing a tsunami warning system, has done considerable work with them. Geo Sciences Australia has been working with Indonesians as well, and in fact, there has been some detailed analysis of Padang using tsunami inundation models, including one from our organisation to assist them in looking at what the impacts of a large tsunami might be.
