Lessons to Learn From a Tsunami Early Warning System That Worked
Despite the incredible damage wrought by the earthquake and tsunami that struck northeast Japan on March 11, the fact is it could have been much worse.
Tsunami detection systems put in place since the Indian Ocean tsunami in 2004 appear to have been vastly improved, helping save the lives of multitudes in Japan and other areas.
Fears in the immediate wake of the disaster were that unknown numbers of people could die on the islands and atolls that dot the Pacific Ocean. But there has been nothing on the scale of the damage caused by the local tsunami in Japan, where it appears some 14,000 people perished.
While mourning the victims of the local tsunami and hoping for the quick restoration of normalcy for the millions displaced, we must take a moment to recognize the achievements of the scientists who have worked hard to improve global monitoring and warning systems, and the first responders who conducted effective evacuations and thus saved countless lives.
The earthquake occurred at 2:46 p.m. near the Pacific coast of Japan’s Honshu Island. The first tsunami warning was issued just six minutes later, an extraordinary achievement that suggests a direct link between the signals from the sensors and the public warning system, excluding human decision making in the middle.
The Pacific Tsunami Warning Center in Hawaii issued its first warning in 14 minutes back in 2004. Given the many weak links in the warning chains back then, the warning didn’t reach all countries affected, with devastating results. Some 230,000 people died in 14 countries. With the Japan tsunami, the center issued an alarm in nine minutes.
The additional resources poured into tsunami detection have paid off. At the warning center in Hawaii, a qualified geophysicist looks at the data from the sensors before issuing the warning. Thus the process cannot take less than nine minutes. But the 2011 tsunami experience may tip the scales in favor of the automated Japanese approach.
For many in the coastal towns of Japan, no warning could have been fast enough. For Iwate prefecture, the Japan Meteorological Agency’s model noted that a three-meter wave had already arrived by the time the warning was issued. For Miyagi prefecture, six-meter waves were predicted within 10 minutes and for Fukushima prefecture, in 20 minutes.
Six minutes was heroic, but still not enough. Clearly, there was no human way the sirens or cellular broadcasts could have been activated in time for the people of Iwate to run; no way orderly evacuations could have been organized.
Did sirens and cellphones give enough warning to the people of Miyagi and Fukushima in the time that remained? This will not be a high priority for Japanese disaster-risk-reduction professionals at the moment, but it is a question that must be answered if we are to learn from this tragedy and reduce the risk of tsunamis everywhere.
Countries vulnerable to local tsunamis, where faults lie very close to the coasts, will have to appreciate that the risk cannot be eliminated, but only managed. Perhaps this is the single most important — and humbling — lesson we can learn from Japan. Excluding the option of moving people away from the coast, the key elements of risk reduction will have to be intelligent land-use planning, enforcement of resilient building codes and mandatory insurance.
Insurance is the most sensible method of managing risk. Here, the high premiums that will attach to the higher-risk land will reinforce land-use rules and building codes. Yet, if people live and work in such areas, the government has a responsibility to help save their lives from a tsunami.
The answers here lie in preparedness (“Your feet are your warning; If you feel an earthquake, run for high ground”) and contingency planning at the household level (in the mere minutes that are available, community action is less effective). It appears that the Japanese authorities have done a good job on these aspects though of course one can always think of improvements.
Many more countries are vulnerable to teletsunamis, or trans-ocean tsunamis. All disaster management authorities in littoral states receive the alert and warning notices issued by the Pacific Tsunami Warning Center and from the Japan Meteorological Agency.
In my experience, the two have come more or less simultaneously. This suggests that, sensibly, the meteorological agency has a special procedure for earthquakes likely to trigger local tsunamis in Japan, while it follows the standard procedure of issuing a warning after assessment by a geophysicist in other cases.
Some seismic waves travel through the earth and reach sensors anywhere in the world more or less at the same time. Therefore, theoretically, detection and monitoring can be done in one location for the whole world. In reality, these activities are duplicated.
Tsunami-detection buoys transmit data through satellite, meaning that they arrive more less seconds apart in different locations depending on how many hops are needed. But clearly the four- and nine-minute warnings that were issued by the two agencies on the March 11 were based solely on earthquake data, not data transmitted from tsunami-detection equipment.
It is when it comes to interpretation that national centers are important. Setting off sirens and broadcasting warnings on cellphones will help people evacuate, but can also trigger mass panic, cause heart attacks in a subset of the populace and disrupt normal life.
Tsunami prediction is an inexact science and false alarms can have major negative consequences. Only national authorities can make the call on issuing evacuation orders. This is what concerned professionals and the media must focus on, not on whether each country has its own tsunami detection and monitoring buoys.
On the basis of monitoring the performance of national authorities responsible for public warnings around the Bay of Bengal, we can see a lot of room for improvement in the interpretation of data and issuing alerts and warnings. For example, Sri Lanka’s cellular networks are equipped to issue localized broadcast warnings (i.e., different messages for vulnerable coastal areas and for inland areas). Yet the whole process of communicating government orders to the cellular operators and even the conventional media is not automated and not done on the basis of standardized templates. This leaves room for error and causes delay.
The government can issue warnings, but it is the general public that must act. In Japan, the media coverage shows that the preparedness training helped. In story after story, one hears of survivors who dropped everything and ran to higher ground, in most cases simply because of the earthquake and not based on an official warning. The land was flat and the sea walls a futile defense against the terrifying power of the roiled ocean. There is little defense against a wall of water in these conditions other than a prepared people.
For tsunamis traveling over the ocean, contingency planning should be at community and organization levels, with periodic checks to see if the plans are current. Various forms of drills and exercises, especially for community leaders and first responders, are essential. Much of this should be voluntary, but in locations such as hostels and hotels with transient populations unfamiliar with local conditions, mandatory standards should be enforced.
The March 11 earthquake shows us that the procedures the Japanese authorities had in place for reducing risks paid off, even if casualty figures exceeding 10,000 suggest otherwise. The Japanese authorities should not be judged on absolute numbers of deaths, but on how many died as a percentage of the vulnerable. By this criterion, I am sure they will come out ahead of the governments whose people died in the 2004 Indian Ocean tsunami.
These deaths will not have been in vain if authorities, professionals and the media in all countries vulnerable to tsunamis use this opportunity to learn from Japan’s (and other Pacific countries’) recent experience to improve their performance in the last mile of the warning chain. This is especially true with regard to government decision making about evacuations, the use of the best-available technologies for alerting the public and preparing people to understand and act in ways that reduce risk.
Rohan Samarajiva, chairman and CEO of LIRNEasia, is a Sri Lanka-based expert on early warning systems for natural disasters.