日本地質災害警報：火山噴發、地震頻發，30年內大地震機率升至八成
——九州新燃岳火山劇烈噴發、小島三日內發生300次地震，日本是否已進入地質活躍期？

近期，日本接連出現火山噴發與密集地震，引發社會對未來大規模災難的憂慮。從九州新燃岳的猛烈噴發，到鹿兒島離島的群發地震，日本氣象廳已緊急提升警戒等級。地質學者更指出，未來三十年內發生大地震的機率已從七成上升至八成。

九州南部橫跨鹿兒島縣的新燃岳火山於2025年6月22日突然噴發，火山灰煙柱高達五百公尺，波及宮崎等地。火山碎屑流蔓延至山體周邊兩公里，氣象廳發佈三級警戒，全面禁止登山活動。新燃岳為日本最活躍的火山之一，曾於2011與2018年劇烈噴發，此次爆發能量比2018年高出約五成。

此次噴發造成鹿兒島機場至少十二班航班停飛，當地居民紛紛配戴口罩，學校則緊急暫停戶外活動。氣象廳警告火山性地震仍在持續，顯示可能已進入新一輪活動期。與此同時，鹿兒島吐噶喇群島於6月21日至23日短短三日內發生多達327次地震，其中四次震度達五級以上，儘管該島為無人島，但鄰近島嶼居民深感恐慌。地震期間多處地區伴隨地鳴聲與地表裂縫，令人憂心是否與海底火山活動相關。面對接連的災害預警，奄美大島的學校已讓學生戴上頭盔上學，周邊海域也暫停漁業作業。地方政府與海上保安廳共同進行海底活動監控，以防突發性災變。

日本政府在2025年更新的《全國地震預測地圖》中指出，南海海槽發生八至九級大地震的三十年內機率，從70%升至80%；而首都圈發生直下型七級地震的可能性也達到47%。其中，東海、近畿、四國與九州太平洋沿岸為高風險區域。此份預測公布後，引發民眾的高度警覺。東京多間超市的罐頭與瓶裝水銷量暴增三倍，各地更加強地震演練，模擬震後「黃金七十二小時」的應變與生存技巧。

地質專家指出，日本位於歐亞板塊、太平洋板塊與菲律賓海板塊的交界處，每年板塊推擠約八公分，能量不斷累積，為火山與地震頻繁的根本原因。九州地區正處於琉球海溝的延伸帶，地底壓力不穩，極易引發地質活動。專家同時指出，南海海槽地震約每百至一百五十年發生一次，上一次大地震為1946年，距今已近八十年，意味風險期即將來臨。而九州火山群的持續活躍，則可能與地幔熱流上湧及板塊張裂有關。

針對災害風險，日本政府已著手推動多項防災改革。首先是強化監測系統，在全國加裝二百座海底地震儀，提升南海海槽的監控密度；同時利用AI技術即時分析火山攝影影像，辨識噴發前兆。其次，在基礎建設方面，東海道新幹線正進行地震瞬停系統測試，東京地區高層建築則全面加裝阻尼器，以減震強度。

在民眾層面，各地積極推廣「黃金十分鐘」自救指引，教育民眾在地震初期如何保命自保；同時推動「區域聯防」制度，由社區指定防災班長，負責老人與兒童的避難協調。從火山灰瀰漫的鹿兒島，到戰戰兢兢備震的東京，日本社會正以高度制度化方式與地質風險共存。正如一位防災專家所說：「災難無法避免，但可以學習如何共存。」

隨著全球進入地質活動頻繁期，日本的經驗或將成為各國防災政策的重要參考。而對普通民眾而言，備妥知識、物資與冷靜的心態，也許正是面對天災最實在的「生命保險」。

Japan Issues Geological Disaster Alert: Volcanic Eruptions, Frequent Quakes—and an 80 % Chance of a Major Earthquake Within 30 Years
Kyushu’s Shinmoedake erupts violently and an offshore island logs 300 quakes in three days: has Japan entered a new period of geologic unrest?

A string of volcanic blasts and clustered earthquakes has rekindled public anxiety about large-scale disasters in Japan. From the powerful eruption of Shinmoedake in southern Kyushu to swarms of tremors around the Tokara island chain, the Japan Meteorological Agency (JMA) has raised alert levels, while seismologists warn that the probability of a catastrophic quake in the next three decades has climbed from 70 % to 80 %.

Shinmoedake’s latest eruption

On 22 June 2025 the 1,421-metre Shinmoedake volcano—straddling Kagoshima Prefecture—erupted suddenly, sending a plume of ash 500 metres into the sky and dusting neighbouring Miyazaki Prefecture. Pyroclastic flows spread two kilometres down the slopes, prompting the JMA to issue an Alert Level-3 notice that bars entry to the mountain. One of Japan’s most active volcanoes, Shinmoedake last erupted violently in 2011 and 2018; the current blast is estimated to be 50 % stronger than 2018.

At least 12 flights were cancelled at Kagoshima Airport, local residents donned masks, and schools halted outdoor activities. Volcanic‐tremor counts remain elevated, suggesting the mountain could be entering a fresh active phase.

300 quakes in the Tokara Islands

Between 21 and 23 June, Suwanosejima in the Tokara archipelago—an uninhabited island lying south of Kyushu—registered 327 earthquakes, four of which exceeded magnitude 5. Although no one lives on the island, nearby communities were rattled by rumbling noises and surface fissures, raising fears of submarine volcanic activity.

Schools on Amami Ōshima have instructed pupils to wear safety helmets, while fishing around the islands has been suspended. Local authorities and the Japan Coast Guard are jointly monitoring the seabed for sudden changes.

Probabilities revised upward

Japan’s 2025 National Seismic Hazard Map now assigns an 80 % likelihood that an M8-to-M9 “Nankai Trough” megathrust quake will strike within 30 years, up from 70 %. The chance of a magnitude-7 quake directly beneath the greater Tokyo area stands at 47 %. High-risk zones include the Pacific coasts of Tōkai, Kansai, Shikoku and Kyushu.

Publication of the new figures sparked a surge in preparedness: sales of canned food and bottled water in Tokyo tripled, and municipalities ramped up “golden 72-hour” survival drills.

Why so many volcanoes and quakes?

Japan sits atop the convergent boundary of the Eurasian, Pacific and Philippine Sea plates, which collide at roughly eight centimetres per year, steadily storing tectonic energy. Kyushu, perched near the Ryukyu Trench, is especially prone to linked volcanic and seismic unrest.

The Nankai megathrust ruptures roughly every 100-150 years; the last event (M8.1) struck in 1946, placing the region within its expected window. The growing vigour of Kyushu’s volcano group may reflect mantle upwelling and extensional faulting.

Government counter-measures

Tokyo is expanding its monitoring network, adding 200 ocean-bottom seismometers to sharpen surveillance of the Nankai Trough and using AI to analyse real-time volcano-cam imagery for eruption precursors. Infrastructure upgrades include instantaneous earthquake-halt systems now on trial for the Tōkaidō Shinkansen and compulsory dampers for skyscrapers in the capital.

Public-education campaigns stress the “golden ten minutes” of self-preservation immediately after a tremor, and neighbourhoods are appointing disaster wardens to aid evacuations of the elderly and children.

Living with the inevitable

From ash-shrouded Kagoshima to quake-ready Tokyo, Japanese society is honing its institutional response to geologic risk. As one disaster-mitigation expert notes, “Catastrophes can’t be eliminated, but coexistence can be learned.”

With the planet apparently entering a phase of heightened tectonic activity, Japan’s hard-won experience may prove invaluable to global readiness. For ordinary citizens, stocking knowledge, supplies and a calm mindset may be the most reliable life insurance against nature’s fury.