2017年2月9日 星期四

從「邏輯概率」破解地震黃金三角迷思

作者:蔡宗翰



去年2月6日,高雄美濃地震,造成台南維冠大樓倒塌,釀115人死亡。

適逢一周年,LINE群組上又瘋傳「黃金三角」、「生命三角求生法」的訊息,消防署日前在官方臉書上表示:「這是錯的!」...


戰火綿延20年

如果你問我:地震黃金三角所定義的存活空間是否存在?

我的答案是:的確存在。

但存在與否跟黃金三角「是否適合作為避難原則」卻完全是兩回事。

地震黃金三角的論點,從1996年被提出後,爭論的戰火綿延至今已滿20年。

這篇不再討論地震科學與避難要領,因為各方專家講的寫的都已相當豐富了,有興趣的朋友也歡迎看看敝人這兩篇拙著:

我們今天換個角度,用邏輯與基本概率常識來探討。

坐穩了!


邏輯與概率

首先,一個避難原則要成立,必須滿足三個條件:
  1. 經統計具最大存活機會。
  2. 具體可操作性。
  3. 考慮人的行為模式。

贊同黃金三角論點者的邏輯是這樣的:

「震後斷垣殘壁的三角夾縫中曾發現倖存者,亦即這個三角夾縫確實創造出了一個讓人存活的空間,所以黃金三角理論成立。」

這個邏輯的問題在於倒果為因,我舉個稍嫌誇張的例子:

「在土石崩塌後發現倖存者卡在兩較大石塊間的夾縫,亦即這個石塊間的夾縫確實創造出了一個讓人存活的空間,所以土石流黃金大石塊理論成立。」

因此,當你遭受土石流侵襲,就迅速瞄準鑽入最大的石頭中吧!

再來一個:

「在一場車禍中發現倖存者卡在大貨車車底與路面空間,亦即這個車底與路面確實可以創造出了一個讓人存活的空間,所以車禍黃金車底理論成立。」

因此,當你預見車輛即將撞上你,就迅速鑽入車底吧!

「土石流黃金大石塊理論」跟「車禍黃金車底理論」?很荒謬嗎?

但有沒有可能活下來,當然有可能!就像樂透頭彩也會有人中獎。

但問題是,今天你拿什麼賭?勝率是多少?

這才是關鍵。


你拿什麼賭?勝率是多少?

回到地震避難。

M.R. Mahdavifar 博士在 Appropriate and Correct Reactions during Earthquakes: “Drop, Cover and Hold on” or “Triangle of Life” 論文中實驗統計數據的結果,你知道「趴下、穩住、掩護(DCH)」比「黃金三角理論」安全幾倍嗎?

12000倍!

換句話說,你真的要拿你最寶貴的生命去博黃金三角 0.0083%(1/12000)的勝率?

要知道,就算某種賭博的勝率是50%(簡直超高了),賭鬼也不會把手上的錢全部押上啊。

但嚴格來講,如果還是堅持要賭這把,我也不能說你100%必敗無疑。

畢竟還存在0.0083%的可能性啊!

3 則留言:

  1. "Group 2: Those who experience earthquakes with intensities VII and more and live in wood structures or buildings made of steel or concrete which the collapse type will be in pancake shape. For this group, the use of “Triangle of life” advice can be useful rather than “DCH”."

    你翻譯給我聽這個叫DCH比黃金三角好.

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    1. 要打作者臉又不敢留名字, 真是窩囔:

      Group 1: People who experience earthquakes with
      intensities III to VII. This group are
      basically under the threat of non-structural
      elements. Therefore the recommendations
      of “DCH” can reduce the risk of damage to
      them. For this group, the “Triangle of life”
      advice does not apply.

      如果你只是以偏概全, 那你跟大部分的網渣沒啥兩樣!!

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    2. 更多補充:

      Table 1. The intensities in EMS98 scale (simplified of [13]).
      Figure 3. The Iso-intensity Map for Bam Earthquake [14].
      I. Not felt Not felt, even under the most favourable circumstances.
      II. Scarcely Felt Vibration is felt only by individual people at rest in houses, especially on upper floors
      of buildings.
      III. Weak The vibration is weak and is felt indoors by a few people. People at rest feel a swaying
      or light trembling.
      IV. Largely Observed
      The earthquake is felt indoors by many people, outdoors by very few. A few people
      are awakened. The level of vibration is not frightening. Windows, doors and dishes
      rattle. Hanging objects swing.
      V. Strong
      The earthquake is felt indoors by most, outdoors by few. Many sleeping people awake.
      A few run outdoors. Buildings tremble throughout. Hanging objects swing
      considerably. China and glasses clatter together. The vibration is strong. Top heavy
      objects topple over. Doors and windows swing open or shut.
      VI. Slightly Damaging
      Felt by most indoors and by many outdoors. Many people in buildings are frightened
      and run outdoors. Small objects fall. Slight damage to many ordinary buildings; for
      example, fine cracks in plaster and small pieces of plaster fall.
      VII. Damaging
      Most people are frightened and run outdoors. Furniture is shifted and objects fall from
      shelves in large numbers. Many ordinary buildings suffer moderate damage: small
      cracks in walls; partial collapse of chimneys.
      VIII. Heavily Damaging Furniture may be overturned. Many ordinary buildings suffer damage: chimneys fall;
      large cracks appear in walls and a few buildings may partially collapse.
      IX. Destructive Monuments and columns fall or are twisted. Many ordinary buildings partially
      collapse and a few collapse completely.
      X. Very Destructive Many ordinary buildings collapse.
      XI. Devastating Most ordinary buildings collapse.
      XII. Completely Devastating Practically all structures above and below ground are heavily damaged or destroyed.

      以上所有資料來自於作者所提到的論文, 由M.R. Mahdavifar, Y.O. Izadkhah, and V. Heshmati 在2009共同發表

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