Pacific Tsunami Warning Center

The Pacific Tsunami Warning Center

On Sunday, December 26, 2004 a tsunami swept through southern Asia killing 220,000 people, leaving millions of others homeless, and completely destroying the public health system in Indonesia ("Mini paper par1"). ¬The tsunami was caused by an undersea earthquake in the Indian Ocean ("Asia's devastation" 9) hitting Indonesia, especially Banda Aceh, the hardest ("Mini paper" par1). The Pacific Tsunami Warning Center (PTWC) claimed that they were able to detect the earthquake (33), between 90 and 150 minutes before the tsunami actually reached shore ("The cruel sea" 16). However, they could not warn people to move out because of communication problems in the areas (16). Although there are many high technologies that the PTWC uses in order to minimize the time to detect tsunamis and warn people in dangerous areas, it is worthless if those areas do not have communication channels.

The PTWC was created in response to the 1946 tsunami in Hawaii (Dudley & Lee 1). On April 1, 1946, an 8.6 magnitude earthquake occurred because of the movement of the sea bottom at the Aleutian Trench (1). As a result, 155 feet high tidal waves were created heading toward Hawaii (1). The hardest hit area was Hilo (5). The tsunami, 8.1 meters high upon reaching Hawaii, completely destroyed Hilo's Waterfront building and killed 159 people (George par7). Moreover, at Pololu Valley, on the island of Hawaii, a school at Laupahoehoe Point and the Puumaile Tuberculosis Hospital, east of Hilo, were completely destroyed by the tsunami (par7). The tsunami not only killed more than 165 people (Dudley & Lee 5), but also cost $26 million (1946 dollars) to the county (George par8). Although, the University of Hawaii and the Hawaiian Volcano Observatory (HVO) were both able to detect the earthquake in Alaska (Dudley & Lee 5), no warning system was in place to warn the population (5). Thus, the PTWC was built in Pacific Ocean to detect and warn of the killer waves.

The Pacific Tsunami Warning Center (PTWC) was established in 1949 at Ewa Beach, Hawaii ("Pacific Tsunami Warning Center" par6). In 1965, the PTWC became an international program, which consists of 26 Member States ("The Tsunami Warning system" par2) over-seen by the National Oceanic and Atmospheric (NOAA). The Member States are organized as the International Coordination Group for PTWC ("The Tsunami Warning System" par2). Any tsunami warning system consists of two major parts which are a network of sensors to detect tsunamis and a communication channel (par1). In addition, the PTWC uses two kinds of information to detect possible tsunamis, seismic data and oceanographic data (par6).

All tsunami warning systems use seismic data to detect earthquakes that can create tsunamis ("Tsunami warning system" par6). However, the PTWC is different in that it will compare this data with oceanographic data (par6) by checking tide gauge stations, which can minimize false alarms ("Tsunami warning system" par6). Oceanographic data is sent from the mooring system called the Deep - ocean Assessment and Reporting of Tsunamis (DART) (par7). DART was established by NOAA's Pacific Marine Environment Laboratory (PMEL) in 1955 (DART, "Background" 1 par1). At present, there are six stations in Pacific Ocean five of which are in the North Pacific and one in the South Pacific ("Getting word..." par16). The objective of DART is to detect tsunamis before tsunamis reach shore ("Tsunami warning system" par8).

The DART system consists of the bottom pressure recorder (BPR) and surface buoy (DART, "Mooring system" par1). The bottom pressure recorder (BPR) or DART bottom package, with a two year life, is located at 6,000 meters under sea-level (DART, "Bottom package" par1). Moreover, the BPR is designed to be free from a surface buoy (par1). The most important thing is that the system can detect water-level changes of less than 1 centimeter (cm) and can compare all data with predicted values (DART, "System overview" par2). Furthermore, the BPR has event and standard data reporting modes (par2). At standard mode or no tsunamis, the BPR will send four 15 second averaged data every hour (par1). However, if 2 of the 15 second data are higher than the expected value, BPR will turn to Tsunami Response Mode (par2). In Tsunami Response Mode, BPR will send data every 15 seconds to the PTWC (par2).

The other major part of DART is the Surface buoy (par1). The surface buoy, with a standard life of one year, is used for real time communication with the PTWC by transmitting the data via the GOES Satellite (DART, "System development" par1). The GOES satellite, which has a self-timed communications channel, is used to show open sea waves and send the data to the PTWC ("DART system development" par1). If the PTWC detects an earthquake, PTWC geophysicists can check an e - mail from the National Earthquake Information Center (NEIC) about the earthquake ("Pacific Tsunami Warning Center" par4). However, if NEIC has not sent an e - mail report about the earthquake, PTWC geophysicists will log onto NEIC system and use data from National Seismic Network (NSN) (par4). After that, the PTWC will forecast and warn areas in danger about the coming tsunamis by issuing bulletins (par6).

There are four basic types of information in Pacific Tsunami Warning which are the Pacific - wide Tsunami Warning Bulletin, Regional Tsunami Warning/Watch Bulletin, Tsunami Information Bulletin and Tsunami Communication test (par20). The Pacific - wide Tsunami Warning Bulletin is issued when tsunamis destroy local areas or the Pacific coastal areas (par20). Pacific - wide Tsunami Warning Bulletin is issued to all PTWC members participating areas on Pacific Ocean (par20). The bulletin will update each hour until the tsunami stops devastating the areas or cancelled (par20). The second bulletin is the Regional Tsunami Warning/Watch Bulletin (par21). This bulletin is issued to alert the possibility of tsunamis and advise to all participants areas after the system detect earthquake more than 7.5 magnitude quake in Pacific Ocean (7.0 magnitude quake in Aleutian Island) (par21).

Moreover, Regional Tsunami Warning/Watch Bulletin usually predicts arrival time of the first tsunamis at the specific areas ("The Tsunami Warning System" par3). The bulletin will update hourly until it is cancelled or moved to Pacific wide Tsunami Warning Bulletin ("Pacific Tsunami Warning Center" par21). The third bulletin is Tsunami Information Bulletin (par22).