Tsunami Warning Center Reference Guide
Summary for National Meteorological and Hydrological Service Managers

Overview

  • An "end-to-end" tsunami warning system (TWS) consists of several interrelated components. A TWS begins with international earth data observations, and culminates with local officials and individuals taking appropriate actions to protect lives and property.
  • The heart of a TWS is its warning center. A full-service center must provide accurate and timely warnings to coastal populations 24 hours per day, 7 days per week. To accomplish this the center must be adequately staffed to have at least two watch standers available at all times, plus sufficient staff and resources for administration, research, outreach, and maintenance functions.

Earth Data Observations

  • The first component of the end-to-end warning system consists of earthquake observations taken by international seismometer networks and, when applicable, the observations from strategically deployed local seismometers.
  • Additional earth data observations needed for an effective TWS are networks of instruments that detect changes in sea level, i.e., track the tsunami wave. These are coastal tide gages and deep ocean buoys.
  • The refinement of initial seismic-based warnings with data on sea level changes can greatly increase the credibility of warnings by decreasing false alarms.
  • International seismometer and sea level networks are usually sufficient for tele-tsunami events, e.g., tsunamis generated by earthquakes far from the area of interest. However, areas prone to "local tsunamis" may require additional local sensors since warnings must be issued much faster for nearby tsunamagenic zones.

Data and Information Collection

  • A second system component is the continuous collection of the earth data observations at warning centers with minimum delay from time of observation to receipt. Communications are the lifeblood of a tsunami warning center. All aspects of operations, from collecting data to disseminating warnings to developing community connections, depend on effective communications.
  • Data from international networks are often available in real-time through the internet and/or satellite downlinks like the World Meteorological Organization’s Global Telecommunications System (GTS). Data from locally deployed networks often require alternate communications paths such as land lines, cell phone, or radio.
  • A center should also acquire real-time earthquake and tsunami information released by other warning centers and earthquake observatories.
  • To ensure data is available at critical times the system should provide for receipt from multiple networks via multiple communications channels. This helps ensure that no important events will be missed.

Tsunami Detection

  • The third component is the TWC's ability to process the received earth data into information for use in assessing the potential that a tsunamagenic event has occurred. To accomplish this, a warning center must detect and analyze earthquakes in the center's ocean basin. Earthquakes that are stronger than established thresholds should activate the center's tsunami investigation procedures.

Warning Decisions

  • Initial tsunami warnings are based solely on seismic data.
  • A warning center requires a variety of hardware, software, and computer applications to obtain, process, and analyze seismic and sea level data as they are received in real-time.
  • Tsunami forecast models and the computer systems they execute on must be developed, adapted, and upgraded at the center by skilled computer programmers.
  • The capability to detect a tsunami signal and rapidly predict its impact requires both scientific expertise and professional judgment augmented by experience. Thus it is not advisable to fully automate the warning system.
  • Once a tsunami's existence and its amplitude have been forecast, a separate system must assess the potential impact of the tsunami. This prediction sub-system should have an appropriate historical database, with potential inundation areas under different scenarios of tsunami occurrences.
  • False alarms, e.g., when a warning is issued but a destructive tsumami does not occur, can be reduced if decision support computer programs are developed to refine initial seismic information.
  • This fourth component of the end-to-end warning system, decision support, includes models of tsunami wave height, models of coastal inundation, and programs that keep warning center personnel aware of any important events detected by the earth data observations.
  • The capability of running "what if" scenarios using decision support technologies is also important for operations.

Warnings and Other Forecast Products

  • Effective warnings for an event are a crucial fifth component in the end-to-end system. Centers should strive to adhere as closely as possible to internationally established product formats and names. Products should be clear, concise, and contents coordinated with local officials well in advance of any events and should not create confusion.

The internationally accepted types of forecast products include the following. Note that these product definitions have been updated since the original publication of the reference guide (page 7-1):

    • Warning (a destructive wave will strike)
    • Watch (a destructive tsunami is possible)
    • Advisory (minor inconveniences due to a non-destructive wave or currents is likely)
    • Information Statement (an earthquake that is not expected to generate a tsunami has been recorded)
    • Centers should have the resources needed to consistently issue warnings for local tsunamis within about three minutes of the causative earthquake, and within about 10 minutes for tele-tsunami events.

Dissemination and Notification

  • Product dissemination processes should take advantage of all technologies available and should be automated as much as possible to speed the warning process. Whenever possible, there should be redundant communication paths to ensure the receipt of critical earth data observations at the tsunami warning center and complete dissemination of warnings from the center.
  • At the same time, warning centers should limit dissemination channels to a manageable number, and use the GTS as the primary channel. Secondary communications pathways like GEONETCast, EMWIN, and RANET should also be used.
  • Centers should establish ways to confirm that main partners and customers receive critical messages, and communications channels should be tested routinely. Problems should be fixed immediately.
  • A warning center must make use of international and local dissemination channels to communicate warnings to as many customers as possible, and with minimal delay.
  • A center needs to work closely with local officials to ensure constituents on the beach have multiple ways of receiving warnings and understand what to do before, during, and after an event.
  • Warning centers must proactively develop positive relationships with partners that assist in the dissemination process and customers that depend on accurate and timely warnings from the center.
  • A center’s outreach and education program must recognize that there are two categories of constituents—partners that assist in the warning process, and customers who rely on the center for timely and accurate products. The goal and focus of outreach should be to educate the public and other groups about tsunami safety and preparedness, and promote the center’s tsunami warning program.
  • The most comprehensive training aid for warning center outreach efforts is the UNESCO/IOC International Tsunami Information Centers (ITIC) "Tsunami Teacher" program. Tsunami Teacher consists of an Information and Resource Toolkit. A feature of the Tsunami Teacher Toolkit is the ability to customize training modules for different audiences.
  • The USA TsunamiReady program is an organized way to assist communities with their efforts to set up their warning operations, evacuations plans, and public education efforts.
  • During actual events a warning center should have a designated Public Affairs Officer to coordinate responses to the media and others.
  • The entire warning system should be periodically exercised to ensure that crucial components are operating successfully and constituents are capable of making optimum use of timely warnings.
  • A warning center’s operations require constant attention and must be provided the resources needed to conduct 24/7 operations as well as maintain all the earth data gages, computers, software, and communications needed to fulfill its mission. A warning center should meet or exceed the capability and interoperability requirements as defined by the Intergovernmental Oceanographic Commission (IOC) and the applicable Intergovernmental Coordination Group (ICG).
  • National and local emergency management officials and other government, academic, and private sector individuals play major roles in educating the population. Tsunami warning centers also play a significant and crucial role in the outreach and education effort.
  • In addition to the need for 24/7 staffing and equipment maintenance a warning center needs resources to conduct and integrate into operations basic and applied research, develop and maintain computers and computer software, and provide staff training. This includes programs for taking over responsibility for one or more other warning centers when necessary.