Tsunamis – Associated Hazards


Drowning is the most common cause of death associated with a tsunami. Tsunami waves and the receding water are also very destructive to structures in the run-up zone. Some other associated hazards include:[1]

Ocean Wave[3]

The impact from coastal flooding by either storm surges or a tsunami can be devastating.

Lives, homes, businesses and infrastructure like roads, railways and industrial areas are all at risk of coastal flooding, with massive potential for social and economic loses.[2]




Aside from the tremendous hydraulic force of the tsunami waves themselves, floating debris carried by a tsunami can endanger human lives and batter inland structures. Ships moored at piers and in harbors often are swamped and sunk or are left battered and stranded high on the shore. Breakwaters and piers collapse, sometimes because of scouring actions that sweep away their foundation material and sometimes because of the sheer impact of the waves. Railroad yards and oil tanks situated near the waterfront are particularly vulnerable. Oil fires frequently result and are spread by the waves.

Port facilities, naval facilities, fishing fleets , and public utilities are often the backbone of the economy of the affected areas, and these are the resources that generally receive the most severe damage. Until debris can be cleared, wharves and piers rebuilt, utilities restored, and fishing fleets reconstituted, communities may find themselves without fuel, food, and employment. Wherever water transport is a vital means of supply, disruption of coastal systems caused by tsunamis can have far - reaching economic effects.[4]

NOAA is leading efforts with federal, state, and local partners to collect data, assess debris, and reduce possible impacts to our natural resources and coastal communities.[5]

Contaminated Water[7]

A tsunami creates a surge of ocean water that can sometimes engulf large geographic areas. As the ocean water comes ashore, drinking water wells can become submerged and potentially contaminated with microorganisms (bacteria, viruses, parasites) and chemicals that can adversely affect human health. The sea salts associated with saltwater flooding of coastal drinking water supplies are not an immediate health threat.

Because of the unpleasant taste of saltwater, most people will not ingest (swallow) a large enough amount to cause immediate health problems. However, disease-causing microorganisms spread by the flood do not normally produce a strong taste. If water containing disease-causing microorganisms is ingested, even in small amounts, it may cause immediate, life-threatening health problems such as chronic diarrhea, cholera, and serious infections. Using contaminated water to clean small cuts and open wounds also poses a danger of serious infections.

Additionally, chemical contaminants often found in floodwater can easily contaminate wells. Chemical contaminants can include fuel products from overturned fuel tanks, or pesticides that may have been stored in flooded areas. Ingesting water containing these types of chemical contaminants may result in threats to life and health.[6]

Fires and explosions can also be hazards associated with tsunamis.

In the aftermath of the massive earthquake that struck northeastern Japan on March 11, 2011, and its subsequent tsunami, several oil refineries and industrial complexes caught fire, including facilities in the Port of Sendai and a petrochemical facility in Shiogama, where a large explosion was reported.[8]

Natural disasters do not necessarily cause an increase in infectious disease outbreaks. However, contaminated water and food supplies as well as the lack of shelter and medical care may have a secondary effect of worsening illnesses that already exist in the affected region.

  • Decaying bodies create very little risk of major disease outbreaks.
  • The people most at risk are those who handle the bodies or prepare them for burial.
  • Insect-transmitted diseases become prevalent.[9]



  1. Ready.gov – Tsunamis: http://www.ready.gov/tsunamis
  2. CA.gov – California Flood Preparedness – Coastal Flooding and Tsunami Dangers: http://www.water.ca.gov/floodsafe/ca-flood-preparedness/fpw-day4.cfm
  3. Image Source: http://www.ready.gov/kids-old/know-facts [Accessed March 14, 2014]
  4. Massachusetts 2013 State Hazard Mitigation Plan, p.16-6: http://www.mass.gov/eopss/docs/mema/mitigation/state-hazard-mitigation-plan/section-16-tsunami.pdf
  5. NOAA – Marine Debris: http://marinedebris.noaa.gov/tsunamidebris/faqs.html
  6. CDC – Tsunamis: Water Quality: http://www.bt.cdc.gov/disasters/tsunamis/waterquality.asp
  7. USGS Water Science School: http://water.usgs.gov/edu/characteristics.html
  8. Earth Observatory: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=49637
  9. CDC – Health Effects of Tsunamis: http://www.bt.cdc.gov/disasters/tsunamis/healtheff.asp