What Is a Storm Surge? The Deadliest Killer in Typhoons Is Not the Wind
Historically, over 70% of typhoon-related deaths are caused by storm surges and flooding rather than strong winds. A storm surge is an abnormal rise in seawater level driven by a typhoon, and its destructive power becomes staggering when it coincides with astronomical high tides.
What Is a Storm Surge
A storm surge is an abnormal rise in sea level caused by the combined effects of a typhoon's strong winds and low atmospheric pressure, which push and pile seawater toward the shore. Strong typhoons can cause water levels to rise by 3–6 meters or even higher—equivalent to a two-story-high wall of seawater rushing onto land.
Two main causes:
- Wind setup effect (primary factor): Persistent onshore winds continuously push seawater toward the coast
- Pressure suction effect: For every 1 hPa drop in atmospheric pressure, the sea level rises by approximately 1 cm. The central pressure of a strong typhoon can be tens of hPa lower than the surrounding areas
Why Storm Surges Are the Deadliest
Historical statistics show that more than 70% of deaths in typhoon disasters result from storm surges and flooding, not from the wind itself:
- The 1970 Bhola cyclone storm surge in the Bay of Bengal claimed approximately 300,000 lives
- In 2013, Super Typhoon Haiyan caused over 6,000 deaths in the Philippines, with the majority attributed to storm surges
- In 1956, Typhoon Wanda (5612) caused significant casualties in Zhejiang Province, with storm surges being the primary cause
Seawater is 800 times denser than air; flowing water just 1 meter deep is sufficient to destroy brick houses.
The Most Dangerous Combination: Storm Surge + Astronomical High Tide
If a typhoon makes landfall around the 1st or 15th day of the lunar month, coinciding with astronomical high tides, the surge overlaps on top of the already high tide levels, drastically increasing the risk of seawall overtopping and breach.
How Coastal Residents Can Prepare
- When an orange or red storm surge warning is issued, evacuation is mandatory for those in low-lying areas, near the seaside, or working on aquaculture rafts. This is not a suggestion—it is a life-saving requirement
- Do not go to the seaside to "watch the tide" or take photos. Incidents of people being swept away by giant waves occur almost every year
- Fishing vessels should return to port early to seek shelter and secure their moorings; personnel must not remain on board
- Know the elevation of your residence and the location of emergency shelters. Ensure evacuation routes avoid cross-sea bridges and coastal highways