August 15th, 2007
Locating an earthquake in 5 minutes
When a powerful earthquake hit Indonesia’s West Java on August 8, 2007, it took exactly 4 minutes and 38 seconds to be detected, located and sized by the German-Indonesian Tsunami Early Warning System (GITEWS) currently under construction in Indonesia. Even more remarkable, the location of the earthquake was found after only 2 minutes and 11 seconds. ‘For comparison, the Pacific Tsunami Warning Center (PTWC) in Hawaii published the location and magnitude of this earthquake after about 17 minutes.’ This very fast analysis was made possible by a combination of hardware and software developed in Germany. As said one German scientist who is leading the project, ‘By the end of 2008 Indonesia will possess the most modern seismological network for tsunami early warning in the world.’
You can see above the components of the GITEWS system. As you can discover, ‘the sensors of the Tsunami Early Warning System comprise seismometers, GPS instruments, tide gauges and buoys as well as ocean bottom pressure sensors.’ (Credit: GITEWS). But the sensors are only one part of the story. The other one is a software called “SeisComP” (Seismological Communication Processor). This software is a new concept for a networked seismographic system developed by GeoForschungsZentrum Potsdam (GFZ) in Germany.
The latest version of the software was recently installed at the Meteorological and Geophysical Agency of Indonesia (BMG) in Jakarta, Indonesia.
Here is a quote from Professor Reinhard Hüttl, Scientific Executive Board of GFZ Potsdam: ‘Due to the German initiative and support, Indonesia has taken a large stride towards its self-defined goal of determining the location and size of large earthquake in less then 5 minutes. The new earthquake monitoring system is already running in real-time operation mode since May 2007 and has successfully detected and located a number of earthquakes. By the end of 2008 Indonesia will possess the most modern seismological network for tsunami early warning in the world.’
For more information, here are additional details taken from the GITEWS Concept page. “The German conception of the establishment of a Tsunami Early Warning System for the Indian Ocean is based on different kinds of sensor systems. In ca. 90 % a tsunami is generated by an earthquake but also volcanic eruptions and landslides may be the triggering events. The conception aims at achieving indicators of a tsunami and its dimension by the analysis of different measurements at a very early stage. While a tsunami wave in the wideness of the sea spreads out with a speed up to 700 km/h, in the treated region a period of about 20 minutes elapses between the wave’s generation and the first contact with the Indonesian mainland. In this timeframe the sensors, which will be installed at different locations inside the considered propagation areas, are able to rapidly detect deviations from normality (anomalies).”
Finally, you might want to read this GITEWS flyer (PDF format, 2 pages, 1.81 MB), from which the above illustration has been extracted.
Sources: GFZ Postdam, via ScienceDaily, August 13, 2007; and various websites
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