The Vital Role of Tsunami Data in Saving Lives

Tsunamis are among the most devastating natural disasters, having caused over 250,000 fatalities and hundreds of billions of dollars in damage globally since the beginning of the 21st century. While predicting these events remains a significant challenge, the collection and analysis of tsunami data are crucial for mitigating their impact and saving lives.

The Global Historical Tsunami Database

The National Centers for Environmental Information (NCEI) maintains one of the world’s only comprehensive global historical tsunami databases. NCEI, co-located with the World Data Service for Geophysics, compiles information on tsunami events dating back to 2000 B.C. In the Atlantic, Indian, and Pacific Oceans, as well as the Mediterranean and Caribbean Seas. This database includes details such as the date, time, and location of tsunamis, their magnitude and intensity, and the maximum height of the resulting waves. It also records the impact of tsunamis, including casualties, monetary damage, and images of the aftermath.

The database is a critical resource for understanding how tsunamis are generated, how they propagate across oceans, and how waves behave as they approach coastlines. It also incorporates Digital Elevation Models (DEMs), which combine bathymetric (undersea elevation) and topographic data to create visual simulations of potential tsunamis and their effects on specific regions. These DEMs are used to predict tsunami arrival times, wave propagation patterns, runup heights, and inundation areas – all vital information for effective warning systems.

Tsunami Warning Centers and Real-Time Monitoring

Data from NCEI is indispensable for the National Weather Service’s (NWS) Tsunami Warning Centers in Hawaii and Alaska. These centers are responsible for issuing warnings to the public when a tsunami threat exists, enabling timely evacuations.

Tsunamis are typically triggered by offshore earthquakes, and seismic waves travel much faster than the tsunami itself. This provides warning centers with a crucial head start. They analyze data from seismic networks to determine the earthquake’s location, depth, and magnitude. If these parameters suggest a potential tsunami, the centers then monitor changes in water levels detected by coastal measuring stations and the Deep-ocean Assessment and Reporting of Tsunamis (DART) buoy system. The DART system, developed by the NOAA Center for Tsunami Research (NCTR), provides real-time tsunami monitoring data.

Based on these findings, along with simulations generated by DEMs, the NWS centers issue alert levels for U.S. Coastlines. These levels include:

• Information Statements: No threat or a distant event where the hazard is not yet determined.
• Watches: Potential hazard is possible.
• Advisories: Strong currents and waves are dangerous for those in or near the water.
• Warnings: Dangerous coastal flooding and powerful currents are expected.

Post-Tsunami Data and Hazard Assessment

NCEI makes tsunami wave data available after an event, and Tsunami Warning Centers employ historical data to establish thresholds for alert levels. This post-event data comes from coastal tide gauges, ocean bottom pressure recorders, and field reconnaissance surveys, where wave height and runup data are collected along coastlines. These surveys are particularly valuable in areas lacking permanent data recorders.

In the 21st century, an average of 14 tsunamis have been observed globally each year, with only one or two typically causing significant damage or fatalities. Our World in Data notes that the Global Historical Tsunami Database includes information on tsunamis classified as “probable” or “definite”. However, predicting the exact time and location of a tsunami remains nearly impossible, leaving vulnerable regions with limited time to prepare.

Hazard assessment, conducted by organizations like the NCTR, focuses on analyzing historical data to identify areas prone to tsunamis. NCEI’s data informs efforts to improve evacuation routes, design tsunami-resistant structures, and guide future development in vulnerable regions.

Educating the Public and Building Resilience

Protecting human lives is the top priority in tsunami preparedness. NCEI’s database supports education efforts tailored to the specific needs of vulnerable populations, considering the historical severity of tsunamis in those areas. The NWS TsunamiReady program recognizes communities that meet specific guidelines, including public education initiatives such as signage, outreach materials, community exercises, and school programs. The National Tsunami Hazard Mitigation Program provides a framework for collaboration between federal, state, and territorial partners to reduce the impact of tsunamis.