日本主要的天災有：氣象災害、地震災害、火山災害、地質災害和海洋災害等五大類；這些災害，彼此之間又會相互影響，進而釀成更慘重的複合型災害；平均每1.6年就會發生一次『巨大天災』（死亡人數超過50人以上）。其中尤以颱風、豪雨、地震及海嘯所引發的災情最為常見且嚴重；此與日本所處的地理位置和自然環境有密切的關係。基於歷次天災的教訓，日本政府乃於1961年頒布「災害對策基本法」，以應各種災害的預警、應變、復原與重建等之需。日本氣象廳針對危害其國人安全的天災之預警發布，原只有「注意報」及「警報」兩種。鑒於2011年311東日本大地震所造成的重大傷亡事件，特自2013年8月起另再加上最高層級的「特別警報」，來提醒全民及早做好防災因應對策。至於預警對策，則有「緊急地震速報」、「海嘯預警」和「緊急警報廣播」等系統，為大眾提供更即時及妥善的災防服務。每當遭遇重大天災之後，日本相關單位均會詳加調查並分析其發生原因和災害特質，進而探討對防救災政策面的衝擊，以及對緊急應變和處置作為的啟發與改進；這種實事求是的態度，值得我們的學習及借鏡。

Five types of hazards, meteorological disaster, earthquake, volcanic disaster, geological disaster and marine calamity, are the major natural disasters in Japan. All above may simultaneously interact with each other, thus turning into compound disasters that lead to catastrophic damage. A calamitous event with the death toll over 50 is taking place every 1.6 year as estimated. Typhoon, heavy rain, earthquake and tsunami are the most common, yet serious causes, which is highly associated with the geographic location and natural environment of Japan. Japan's legislative framework for the reduction of risk from natural disaster, which consists of the 「Disaster Countermeasures Basic Act」 passed in 1961, covers a wide range of disaster-related issues such as early warning, emergency response, recovery and reconstruction. Japan Meteorological Agency used to issue two kinds of early warnings for natural disasters: ＂advisories＂ (注意報 chuuihou) and ＂warnings＂ (警報 keihou). In 2013, a three-classed system with the newly added ＂special warnings＂ (特別警報 tokubetsu keihou) was introduced after the 2011 earthquake off the Pacific coast of Tōhoku (a.k.a. The Great East Japan Earthquake). As for the warning strategies, there are Earthquake Early Warning, Tsunami Warning System , Emergency Warning System (radio and TV broadcasts) and also known as EEW , TWS and EWS respectively.