太平洋海啸预警中心

The Hawaii Pacific Tsunami Warning Center is responsible for issuing warnings to the state of Hawaii and American interests around the Pacific. It also functions as an international warning center for other countries in the Pacific.

After the Indian Ocean tsunami of December 2004, the Pacific Tsunami Warning Center took on the role of monitoring the Indian Ocean as well, sharing this task with the Japanese Meteorological Agency.

Until then, there was no monitoring system in the Indian Ocean, and that contributed to the large number of casualties in the December 2004 tsunami. In the next six months, this duty will be formally passed to Asian countries.

Regardless of recent technological advances in monitoring water levels and waves, much of the activity the center records is based on historical data, at least as far as initial warnings are concerned.

In the immediate aftermath of an earthquake, geophysicists here are concerned with trying to determine what type of earthquake has occurred. They look at many complex variables and, based on that data and historical references, they decide whether to issue a warning or not.

Geophysicist Gerard J. Fryer explains their thinking.

"If the earthquake is under the ocean and shallow and big, then we'll issue a warning. It will either be a warning just to a fixed area around the earthquake or, if the earthquake is large enough, it will be an expanded warning."

Fryer says historical data suggest that there could be potentially massive earthquakes to come before the earth goes quiet again.

"If the present sequence (of earthquakes) is anything like what happened in the last century, we have about five or six years more to go before the earth goes back to sleep. So, in the next five or six years it's not at all unlikely that we have two or three more great magnitude-9 earthquakes somewhere on earth."

Events like the Indian Ocean tsunami helped scientists obtain further funding to implement new technologies to monitor tsunamis. Fryer says disasters like that help with funding tsunami warning systems.

"The big new development has been deep floor gauges that actually measure the tsunami. If it hadn't been for the Indian Ocean tsunami of 2004 we would not have the deep ocean gauges that we now have all around the Pacific and in the Indian Ocean and in the Atlantic."

There are now 40 DART deep water gauges in oceans around the world compared to only six before the 2004 disaster.

A major challenge for the center has always been to avoid issuing unnecessary warnings. This is being achieved through new projection models that take into account the directionality of an earthquake occurring under the ocean and the effect it may have.

For CRI, I am Li Dong.