Tsunami warning center on alert

March 28, 2005 Bulletin

The Pacific Tsunami Warning Center (PTWC) near Honolulu issued a bulletin at 1:41 p.m. Eastern Standard Time today that an earthquake measuring 8.5 on the Richter scale in northern Sumatra has the potential to “generate a widely destructive tsunami in the ocean or seas near the earthquake.”

The center, operated by the National Oceanic and Atmospheric Administration, recommended in its bulletin the “evacuation of coasts within a thousand kilometers of the epicenter and close monitoring to determine the need for evacuation further away.”

Marine Maj. Guillermo Canedo, a spokesman for the U.S. Pacific Command in Honolulu, said Pacom officials were assessing the potential of today’s earthquake to cause a tsunami. The hospital ship USNS Mercy is still performing humanitarian relief operations off Sumatra following last December’s tsunami.

Stuart Weinstein, a geophysicist at the center said in an interview earlier this month that destructive tsunamis are generated by earthquakes of 8.5 magnitude or more on the Richter scale.

The earthquake that caused last December's tsunami, which caused widespread damage and killed hundreds of thousands of people in the Indian Ocean region, was determined to have a magnitude of 9 on the Richter scale.

Center officials said they used a tide gauge on Cocos Island in the Indian Ocean about 700 miles southwest of the southern tip of Sumatra in Indonesia and observed a small tsunami generated by today’s earthquake. The gauge is operated by Australia’s Division of Oceanography.

Weinstein said information tide gauges are transmitted via Internet connections to PTWC. This information is then fed into powerful Sun Microsystems Inc. microcomputers, which help PTWC scientists produce tsunami warnings.

Besides the Cocos Island tide gauge, PTWC can now tap into information from a gauge in Sri Lanka operated by the University of Hawaii. Weinstein said that after last December’s tsunami, a satellite communications connection was installed on the Sri Lanka gauge so it could feed information to PTWC.

In today’s bulletin, center officials cautioned that PTWC does not have systems outside the Pacific Ocean “so it will not be able to determine whether or not a tsunami was generated." The bulletin added that authorities can determine that danger has passed if no tsunami waves are generated within three hours of the earthquake, or 2:41 p.m. Eastern Standard Time.