About man-made marine disasters

Among the many natural disasters faced by human beings, disasters originating from the ocean are called marine disasters. Marine disasters mainly include storm surge, disaster wave, sea ice, red tide and tsunami. They mainly threaten the ocean and coastal zone, and some also endanger the urban and rural economy and the safety of people's lives and property in the vast deep areas from coast to land.

Storm surge is an abnormal fluctuation of sea surface caused by strong weather systems such as typhoon, temperate cyclone, cold front and strong wind, and sudden pressure change, also known as storm surge or meteorological tsunami. Storm surge is a kind of gravity long wave with a period ranging from several hours to several days, which is between earthquake tsunami and low-frequency tide. The amplitude (that is, the tide level of storm surge) is usually several meters, and the maximum can be reached.

Catastrophic waves are waves with catastrophic damage caused by wind in the ocean, and their acting force can reach 30-40 tons per square meter. Sea ice refers to all the ice in the ocean, including salt water ice, river ice and icebergs. In areas with severe ice conditions or extremely cold winter, severe freezing often occurs, which freezes coastal ports and waterways and endangers coastal economy and people's lives and property safety. Among the huge pieces of ice that are broken after continental glaciers or continental shelf oceans slide into the sea, the one that is more than 5 meters above the sea surface is called an iceberg, which was hit by this iceberg and sank in the maiden voyage of the North Atlantic.

Red tide refers to the phenomenon of seawater discoloration caused by explosive reproduction of marine plankton under certain conditions, and it is also a phenomenon of marine pollution. Red tides mostly occur in inland seas, estuaries, ports or waters with upwelling, especially in warm waters. The color of red tide is determined by the advantages of forming red tide and the pigments of non-plankton species. For example, the red tide formed by noctiluca scintillans is red, while green dinoflagellates are green when they multiply, and diatoms are often brown. Red tide is actually a general term for all kinds of color tides. Red tide will kill marine animals and cause great harm. Tsunami is a huge wave caused by underwater earthquake, volcanic eruption or underwater collapse and landslide. The conditions for destructive earthquakes and tsunamis are: vertical movement in seismic tectonic movement; The focal depth is less than 20-50km; Above 6.5 on the Richter scale, without earthquake shock or elastic vibration of the seabed, a weak tsunami may be triggered. Underwater nuclear explosions can also produce artificial tsunamis. The damage of tsunami to people, livestock, trees, buildings and ports in coastal areas mainly occurred in the Pacific coast of Japan, the western, southern and southwestern Pacific Ocean, and the coasts of Hawaii and Aleutian Islands. Although the tsunami is very harmful, its frequency is limited, especially people can predict that its harm has been greatly reduced.