The German engineers drew on a 60-year history of tsunami early warning research dating to the National Oceanic and Atmospheric Administration's Pacific Tsunami Warning Center,. The new system incorporates many recognizable elements from the legacy NOAA and Japanese systems, but also features new research and design elements and integrated, newly designed software and hardware.
The Japanese early warning system is considered by researchers to be the most advanced in the world in its scale and distribution. The basic tools are seismometers, tidal gauges, pressure sensors and waterborne buoys—instruments on which the Indonesian system is based. It also links a new earthquake alert circuit that went online in 2007—connecting more than 1,000 land-based and ocean-bottom seismometers under the aegis of the Japan Meteorological Agency—with Pacific-wide tsunami alert coordinating centers in Japan, Alaska and Hawaii. The GFZ-designed system, in comparison, is a bit more compact, more connected to GPS monitoring, and integrated with newly developed software. This SeisComP 3.0 software analyzes seismological and sensor data, and is linked to a local grid of tsunami wave data models. It is all designed to make the system faster and more responsive to the near-field tsunamis that threaten Indonesia.
In a near-field event the most crucial element is the seismic network, Lauterjung says. Each node is equipped with a seismometer recording ground motion over a wide range of frequencies and along three axes. The stations are linked to SeisComP 3.0, which uses the inbound data to calculate earthquake location and magnitude. Measurements from the whole system are matched with a database holding thousands of modeled tsunami simulations calculated across the Sunda Arc: some 3,500 now, with another 7,000 in the works.
Not every earthquake triggers a tsunami—it takes a vertical shock to transfer energy to a water column. The GFZ design accounts for this distinction by including GPS units in the seismic stations. These concrete-mounted units transmit data continuously and align with geodetic stationary, or base, points, allowing observers to calculate nearby deformation in Earth's crust.
Offshore, 4.5-meter steel buoys are attached to pressure plates on the ocean floor set with instruments: an acoustic modem for transmission, another seismometer for the seafloor, and gauges which detect sudden changes in water pressure above. The pressure plates can measure changes in sea level within an accuracy of several millimeters. Also, a GPS-referenced data stream from the buoy, overlaid with an algorithm and mathematical filtering, calculates sea-surface heights by measuring the buoy's movement compared with a set of land-based reference stations.
Last but not least are the tidal gauges measuring sea-level changes off the beach. The stations look like orange boxes sitting on dock pilings, and comprise two component sets: One is a set of three different kind of tide gauge sensors, including a radar hanging like a lure at the end of a rod. The other contains data processors and—again—an integrated GPS antenna, which monitors the stability and displacement of the station during earthquakes. Onboard algorithms for the sensors go into motion if there is a sudden tidal outrush and indicate both the timing of a potential tsunami arrival and its relative strength.
The satellite-linked network now stretches like a veil over the coastal face of Sumatra and its smaller islands: 10 GFZ tidal stations dot the coastline, along with 21 seismometers, 10 buoy systems and 20 GPS stations. The Indonesians themselves ordered another 105 seismic stations in addition to the 15 donated by Japan, 10 from China and several from France. The upshot, Lauterjung says, is that Indonesia now has one of the densest seismic networks in the world.
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Add CommentAs stated, Japan is the country most prepared for tsunamis. As I understand, in this case the primary failure was the underestimation of the potential wave height. Earlier warnings may help, though, especially if they could include more and accurate information about the incoming wave.
Reply | Report Abuse | Link to thisEffectively communicating timely warnings to large stretches of the Pacific Rim may be a more difficult matter.
Dr Goldfinger didn't say that the earthquake is "sometimes" the warning, he said it is always the warning. If people hesitate to evacuate to higher ground because they are waiting for some signal that takes minutes to happen then they are going to decrease their chance of getting out of harms way. If you live near a subduction zone (as I do on the Oregon Coast) when you feel a substantial earthquake you get to higher ground immediately. Much of the money spent on this system could be better utilized educating people that earthquake means run. These kinds of earthquakes happen infrequently so what happens tens of years down the road when funds from Germany and other rich donors have dried up and the system isn't maintained, but the locals still have some faith that it will work and save them? If you are working in remote areas in less developed countries keeping it simple and cheap is what will save lives.
Reply | Report Abuse | Link to thisTrue, coastal earthquakes can forewarn of a tsunami, but as I understand enormous tsunamis can also be produced by an earthquake on the other side of the ocean, thousands of miles away... Also, not all earthquakes produce tsunamis, so evacuating Seattle, for example, for any tremor might not be prudent in all cases.
Reply | Report Abuse | Link to thisLook at the earthquake maps from the 03/11 quake. Last I looked, I saw more than a thousand aftershocks, many in excess of M5, some, (couldn't see how many) well in advance of the Godzilla event. Most of the maps indicate seismic activity offshore, but no perceptible ground acceleration onshore. (One map did seem to show ground acceleration onshore)
Reply | Report Abuse | Link to thisThus, if Goldfinger thinks the quake is always the signal to take refuge, he is wrong. Undoubtedly, however, in the case of any massive ground acceleration in coastal locations, the correct reaction strategies are (a) run to high ground as soon and as fast as possible if high ground is nearby, or: (b) climb as high as possible in or on a sturdy building or man-made structure if no high ground is near, or (c) take refuge in a bouyant tsunami pod that would not be crushed by debris.
Tragic that some villagers thought they would be safe behind tsunami walls and didn't move to higher ground. another lesson learned.
I live in Tokyo and have been a few times to the tsunami struck area after the disaster. One thing that struck me listening to survivors who were actually caught by the tsunami was that many of those who were in their cars were unaware of the magnitude of the shock. In a moving car it can sometimes be difficult to estimate the danger potential of an earthquake. In the future, cars need to be rigged with an automatic override function that activates radio and GPS warning systems. For example, the GPS automatically switching to a route directing to higher ground or a point where you can access higher ground on foot.
Reply | Report Abuse | Link to thisEver since the tragedy of Japan there has been a lot of talk of early warning systems and how they can save lives, but is getting people to run to higher ground the best way of saving lives and property? It seems that the broader issues is the way cities can survive natural and man made disasters.
Reply | Report Abuse | Link to thisWhen Japan rebuilds will it put back the same structures that caused the devastation in the first place, or will it really re-think how to best redevelop the area in order for the inhabitants to survive a greater tsunami/earthquake? If people are told to run to higher ground when the sirens wail how will older people and physically disabled sprint up the mountain in order to save their lives? What about children, or people that may be several miles away from higher ground? Is this the best we can come up with. Jogging shoes. We have to better that this. The quake in Haiti should have been a wake up call, but we slept that that one and the people of Haiti are still suffering. What about New Orleans? How many have to die before we do the right thing?
Given the fact that Japan has the best tsunami predictive equipment in the world, then it is obvious that present technology is vastly inadequate. Rather than determining wave height and seismic changes, it seems to me that there must be precursors to environmental catastrophic events, in this case involving sudden massive vertical shifting of the ocean floor. Sudden cataclysmic geological events must have significant precursors that we are missing. To prevent tragic events as in the case of the Japan near field disaster, minutes of notice are insufficient. An earthquake or a sudden volcanic eruption can be considered to be a gigantic bomb which suddenly explodes. It is our challenge to adjust our technology to calculate beyond minutes, or even hours, to months or years in order to perform needed evacuations and harden or shut down infrastructure systems such as power plants. Technology must be adjusted and refined to detect and analyze and mobilize more sophisticated precursive warning systems. Alternative systems must be deployed.
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