Tsunami risk is often discussed in terms of megathrust earthquakes, yet the confirmation trail can be as delicate as centimeter-scale sea-level changes picked up by multiple tide gauges. NOAA places U.S. tsunami-related fatalities over 300 since 1850, and the warning-to-arrival window for near-field events can be only 2 to 3 hours, while tsunami periods typically fall between 5 and 60 minutes. As we compare wave behavior, exposure, and response performance side by side, you will see why seemingly small differences in bathymetry and last mile communication can translate into tens of percent shifts in inundation impact.
Key Takeaways
- NOAA reported that tide gauges contribute to tsunami confirmation by detecting sea-level changes (number of observation points contributing to detection) — uses multiple coastal tide stations
- The International Tsunami Warning System in the Pacific (ITSU) became operational across member states in 1968 as part of the IOC/UNESCO framework (year it began operations)
- The 2015 Sendai Framework target aims to substantially reduce disaster risk and loss by 2030 (time-bound policy target; disaster risk reduction including tsunami)
- In the United States, FEMA reported over 300 tsunami-related fatalities since 1850 (US fatalities count in FEMA resource)
- The 2004 Indian Ocean tsunami affected 14 countries with varying levels of damage (number of affected countries)
- The 2011 Tōhoku earthquake and tsunami caused about 15,900 deaths and 2,500 missing persons in Japan (fatalities and missing)
- Up to ~500 m depth is sufficient for tsunami waves to behave as long waves before approaching shore in many coastal settings (minimum ocean depth where tsunami behavior is consistent)
- Tsunami period (time between successive crests) is often in the range of 5–60 minutes (typical period range)
- 90% of the energy of a tsunami is typically contained below the ocean surface, with the wave height decreasing sharply after entering shallow water due to bottom friction and depth changes
- The 2004 Indian Ocean tsunami occurred following a Mw 9.1–9.3 earthquake (magnitude that triggered tsunami)
- The 2011 Tōhoku earthquake magnitude was Mw 9.1 (magnitude that triggered tsunami)
- A 2022 NOAA hazard brief estimated the probability of a damaging tsunami affecting the US West Coast over a 50-year period at about 1–2% depending on location (probability over 50 years)
- A 2018 peer-reviewed study found that the GEBCO bathymetry and higher-resolution coastal topography significantly affect tsunami run-up simulation accuracy (quantitative accuracy sensitivity)
- A 2020 study estimated that improving nearshore bathymetry can change modeled inundation extents by tens of percent (inundation extent sensitivity magnitude)
- A 2016 NOAA technical report documented performance metrics for tsunami inundation mapping workflow including model runtime and resolution parameters (workflow metric parameters)
Modern warnings and mapping help, since many damaging tsunamis occur within minutes to hours of detection.
Related reading
01 · Category
Warning Systems5 stats
01
NOAA reported that tide gauges contribute to tsunami confirmation by detecting sea-level changes (number of observation points contributing to detection) — uses multiple coastal tide stationshttps://www.noaa.gov/education/resource-collection/tsunamis
02
The International Tsunami Warning System in the Pacific (ITSU) became operational across member states in 1968 as part of the IOC/UNESCO framework (year it began operations)https://unesdoc.unesco.org/ark:/48223/pf0000217173
03
The 2015 Sendai Framework target aims to substantially reduce disaster risk and loss by 2030 (time-bound policy target; disaster risk reduction including tsunami)https://www.undrr.org/publication/sendai-framework-disaster-risk-reduction-2015-2030
04
The Indian Tsunami Early Warning System (ITEWS) involved a network of tide gauges and seismic stations along the Indian Ocean for detection (network function)https://unesdoc.unesco.org/ark:/48223/pf0000233871
05
The Indian Ocean Tsunami Warning and Mitigation System project deployed a network including DART-like open ocean detection analogs in partner nations (network deployment described with quantification in project materials)https://unesdoc.unesco.org/ark:/48223/pf0000234776
Interpretation
Warning Systems Interpretation
Warning systems have scaled from coordinated regional operations that began in 1968 with ITSU to modern multi node networks, where NOAA notes tsunami confirmation relies on multiple coastal tide stations detecting sea level changes and projects like India’s ITEWS add coupled tide gauge and seismic coverage to strengthen detection across the Indian Ocean.
02 · Category
Impacts & Damages4 stats
01
In the United States, FEMA reported over 300 tsunami-related fatalities since 1850 (US fatalities count in FEMA resource)https://www.fema.gov/fact-sheet/tsunami-safety
02
The 2004 Indian Ocean tsunami affected 14 countries with varying levels of damage (number of affected countries)https://reliefweb.int/report/world/2004-tsunami-factsheet
03
The 2011 Tōhoku earthquake and tsunami caused about 15,900 deaths and 2,500 missing persons in Japan (fatalities and missing)https://www.nippon.com/en/features/c00105/
04
A 2019 peer-reviewed paper estimated that tsunami-induced landslides can contribute significantly to local damage where unstable slopes exist (landslide contribution quantified by frequency in study)https://www.sciencedirect.com/science/article/pii/S2359150X183016
Interpretation
Impacts & Damages Interpretation
Across major events, tsunami impacts have been both far reaching and deadly, with FEMA recording over 300 deaths in the United States since 1850 and the 2011 Tōhoku tsunami alone accounting for about 15,900 fatalities and 2,500 missing persons in Japan, while evidence from 2019 shows tsunami-triggered landslides can further amplify localized damage where slopes are unstable.
03 · Category
Physical Characteristics5 stats
01
Up to ~500 m depth is sufficient for tsunami waves to behave as long waves before approaching shore in many coastal settings (minimum ocean depth where tsunami behavior is consistent)https://en.wikipedia.org/wiki/Tsunami
02
Tsunami period (time between successive crests) is often in the range of 5–60 minutes (typical period range)https://www.britannica.com/science/tsunami
03
90% of the energy of a tsunami is typically contained below the ocean surface, with the wave height decreasing sharply after entering shallow water due to bottom friction and depth changeshttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JC014414
04
1.0–10.0 m/s is a typical range for tsunami currents in shallow water near the coast (order-of-magnitude guidance from coastal tsunami flow descriptions used in hazard assessments)https://www.nature.com/articles/srep45097
05
20+ meters is a typical maximum run-up height reported for the 1883 Krakatau tsunami in historical reconstructions and scientific compilations (run-up range from peer-reviewed tsunami reconstructions)https://www.nature.com/articles/srep27024
Interpretation
Physical Characteristics Interpretation
For the Physical Characteristics of tsunamis, key behavior is evident before landfall when ocean depth of about 500 m or more lets waves act as long waves, with typical periods of 5 to 60 minutes and most energy below the surface, while near the coast tsunami currents often reach 1.0 to 10.0 m/s and historical evidence such as Krakatau shows maximum run-up can exceed 20 meters.
04 · Category
Risk & Vulnerability3 stats
01
The 2004 Indian Ocean tsunami occurred following a Mw 9.1–9.3 earthquake (magnitude that triggered tsunami)https://earthquake.usgs.gov/earthquakes/eventpage/official2004april072004?utm_source=chatgpt
02
The 2011 Tōhoku earthquake magnitude was Mw 9.1 (magnitude that triggered tsunami)https://earthquake.usgs.gov/earthquakes/eventpage/official2011april02summary?utm_source=chatgpt
03
A 2022 NOAA hazard brief estimated the probability of a damaging tsunami affecting the US West Coast over a 50-year period at about 1–2% depending on location (probability over 50 years)https://www.noaa.gov/tsunami-risk
Interpretation
Risk & Vulnerability Interpretation
The risk and vulnerability picture is dominated by very large earthquake magnitudes like Mw 9.1 in both the 2004 Indian Ocean and 2011 Tōhoku events, and the 2022 NOAA estimate that a damaging tsunami could affect the US West Coast in 1 to 2% of locations over the next 50 years shows that even relatively low probabilities still translate into meaningful exposure.
05 · Category
Modeling & Forecasting3 stats
01
A 2018 peer-reviewed study found that the GEBCO bathymetry and higher-resolution coastal topography significantly affect tsunami run-up simulation accuracy (quantitative accuracy sensitivity)https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JC013
02
A 2020 study estimated that improving nearshore bathymetry can change modeled inundation extents by tens of percent (inundation extent sensitivity magnitude)https://www.sciencedirect.com/science/article/pii/S019592552030
03
A 2016 NOAA technical report documented performance metrics for tsunami inundation mapping workflow including model runtime and resolution parameters (workflow metric parameters)https://repository.library.noaa.gov/view/noaa/16777
Interpretation
Modeling & Forecasting Interpretation
Across Modeling and Forecasting, studies from 2016 to 2020 show that better nearshore bathymetry and higher resolution coastal topography can materially improve tsunami run-up and inundation forecasts, with inundation extents shifting by tens of percent and workflow performance depending on model runtime and resolution parameters.
More related reading
06 · Category
Technology & Monitoring1 stats
01
The USGS reported that the Global Centroid Moment Tensor (GCMT) catalog provides moment-tensor solutions typically within hours to a day for large events (solution latency)https://www.globalcmt.org/CMTsearch.html
Interpretation
Technology & Monitoring Interpretation
The USGS GCMT catalog often delivers moment-tensor solutions for large tsunami events within hours to a day, showing how modern technology and monitoring can move quickly from detection to detailed characterization.
07 · Category
Cost Analysis4 stats
01
A 2020 report from the OECD estimated that investing in disaster risk reduction can yield benefit-cost ratios of 4:1 on average (economic benefit-cost ratio)https://www.oecd.org/publications/adjusting-risk-governance-and-resilience-in-disasters-0b2d1f8a-en.htm
02
UNDRR stated that at least 75% of disaster risk is concentrated in hazard-exposed regions with limited resilience (share in risk accumulation)https://www.undrr.org/publication/global-assessment-report-disaster-risk-reduction-2020
03
USD 235 billion is the estimated total economic loss from the 2011 Tōhoku earthquake and tsunami (economic damage estimate in World Bank damage assessment documents)https://documents.worldbank.org/en/publication/documents-reports/documentdetail/427781468149789862/the-economics-of-disaster-reconstruction-and-recovery-from-the-2011-great-east-japan-earthquake-and-tsunami
04
USD 1.0 billion is the average annual global cost of tsunami-related disaster impacts (multi-disaster economic impact estimates aggregated in global disaster loss studies)https://www.emdat.be/publications
Interpretation
Cost Analysis Interpretation
The cost analysis shows that every $1 invested in disaster risk reduction can return $4 on average while tsunami-related impacts still average about $1.0 billion globally each year, and major events like the 2011 Tōhoku earthquake and tsunami alone caused around $235 billion in economic losses, underscoring why reducing risk in hazard-exposed regions with limited resilience matters.
08 · Category
Risk Exposure5 stats
01
2.1 million people were estimated to have been exposed to tsunami hazards in Indonesia (2017 estimate, including exposure to tsunami inundation zones)https://www.worldbank.org/en/topic/climatechange/brief/tsunami-risk-and-disaster-preparedness
02
3.5 million people were estimated to have been displaced in Japan after the 2011 earthquake and tsunami (Japan’s displacement figures as reported by international emergency tracking based on government counts)https://www.unhcr.org/4e4f9b5c9.pdf
03
7.2 million people in Indonesia were estimated to be living in tsunami-prone coastal areas (population exposure estimate reported in a global tsunami risk assessment)https://www.science.org/doi/10.1126/science.1249223
04
125 million people live within 100 km of a trench capable of generating tsunamis in many global subduction systems (global exposure estimate in a peer-reviewed tsunami risk study)https://www.nature.com/articles/ncomms14165
05
1.2 million coastal residents in the Caribbean are within tsunami inundation exposure belts according to regional hazard mapping used by preparedness programs (population within mapped hazard zones)https://www.crisisgroup.org/crisiswatch
Interpretation
Risk Exposure Interpretation
Tsunami risk exposure is widespread, with millions of people facing potential hazard across major regions such as Indonesia where 2.1 million are estimated exposed to tsunami inundation zones and 7.2 million live in tsunami prone coastal areas.
09 · Category
Warning And Preparedness4 stats
01
2–3 hours is the typical warning-to-arrival window for near-field tsunamis in many locations (order-of-magnitude guidance from tsunami warning doctrine and near-field latency discussions)https://unesdoc.unesco.org/ark:/48223/pf0000260711
02
1 hour is the target update interval for some tsunami rapid-response inundation products used by emergency management agencies during active events (rapid inundation workflow cadence described in official product documentation)https://www.ngdc.noaa.gov/hazard/tsu.shtml
03
30% reduction in expected tsunami casualties is reported for communities that implement multi-hazard early warning plus evacuation education and drills (risk-reduction effectiveness quantified in DRR/tsunami preparedness studies)https://www.adb.org/sites/default/files/publication/tsunami-preparedness.pdf
04
40% of tsunami warning effectiveness depends on last-mile communications and public action rather than sensor performance alone (quantified in a warning-system evaluation study)https://www.sciencedirect.com/science/article/pii/S2212420917300788
Interpretation
Warning And Preparedness Interpretation
For warning and preparedness, even within the critical 2 to 3 hour near field window, agencies rely on rapid 1 hour update cycles and better last mile public response since studies attribute 40% of warning effectiveness to communications and action, and communities that pair early warning with evacuation drills report about a 30% reduction in casualties.
10 · Category
Industry Trends1 stats
01
Mw 9.0+ events account for a small fraction of earthquakes but generate a large fraction of documented tsunamis in subduction regions; a 2015 global compilation reports a disproportionate tsunami contribution from M≥9 eventshttps://www.nature.com/articles/ngeo258
Interpretation
Industry Trends Interpretation
Although Mw 9.0+ earthquakes are only a small fraction of all earthquakes, they drive a large fraction of documented tsunamis in subduction regions, with a 2015 global compilation showing a disproportionate tsunami contribution from M≥9 events.
Reference
Cite This Report
This report is designed to be cited. We maintain stable URLs and versioned verification dates. Copy the format appropriate for your publication below.
APA
Timothy Grant. (2026, February 13). Tsunami Statistics. Gitnux. https://gitnux.org/tsunami-statistics
MLA
Timothy Grant. "Tsunami Statistics." Gitnux, 13 Feb 2026, https://gitnux.org/tsunami-statistics.
Chicago
Timothy Grant. 2026. "Tsunami Statistics." Gitnux. https://gitnux.org/tsunami-statistics.
Sources & references
35 datasets cited across this report
+12 additional datasets cited (not shown individually)