尼泊爾地震傷亡遠低於預測

Amid the horror and devastation around Nepal’s Katmandu Valley after Saturday’s 7.8-magnitude earthquake, seismologists and earthquake-focused engineers are remarking on how low the death counts are — particularly in the capital — compared to many predictions for the densely populated, deeply impoverished and ill-prepared region.

在尼泊爾加德滿都谷地週六遭遇7.8級地震的恐慌與浩劫中，地震學家和地震方向的工程師們卻一直在感嘆死亡人數之少，尤其是首都的死亡人數。相對於諸多預估數據，這片人口密集、身陷赤貧又毫無準備的土地上，實際的遇難者要少得多。

And this assessment presumes that fatalities will climb much higher than the 4000 counted so far. But to reach even the low end of past estimates, the death toll would have to rise enormously.

這種說法所預計的死亡人數要比現在的4000多人高出很多。但即使是按照以往預估的最低值來算，現在的死亡人數也低得多。

In 2012, for example, this was the warning for the Katmandu Valley from the United Nations Office for Disaster Risk Reduction:

例如，2012年聯合國減災辦公室(United Nations Office for Disaster Risk Reduction)就曾向加德滿都谷地發出如下提醒：

Conservative estimates are that the next big earthquake could result in 100,000 dead, 200,000 injured and one to two million people displaced

保守估計，下一場大地震將造成10萬人遇難，20萬人受傷，100萬至200萬人無家可歸。

Why the difference? For one thing, it appears that, at least for the capital, this earthquake was not nearly a worst case.

實際狀況爲何與此相去甚遠？一方面，至少以首都的情況來看，這並非最嚴重的一次地震。

If the great 1934 Bihar-Nepal earthquake occurred with today’s population and structures, vastly higher losses would occur, as GeoHazards International and Nepal’s National Society for Earthquake Technology found in a 1999 analysis.

國際地質災害組織(GeoHazards International)與尼泊爾國家地震技術科學會(Nepal's National Society for Earthquake Technology)1999年發佈分析報告稱，如果1934年的比哈爾-尼泊爾地震(Bihar-Nepal earthquake)重演，以如今的人口規模和結構來看，死亡人數將大幅上升。

Susan E. Hough, a United States Geological Survey seismologist, sent these thoughts on Sunday:

美國地質調查局的地震學家蘇珊·E·哈夫(Susan E. Hough)週日時發表瞭如下觀點：

As tragic as the losses are, it seems clear the city was not flattened. I’ve been struck by damage photos — not only the damage they show, but the damage they don’t show to apparently intact buildings in the background. This seems to go hand-in-hand with the ShakeMap, which is poorly constrained but shows intensities 7-8 in the near-field, not 9-10.

儘管傷亡人數令人悲嘆，但很明顯這座城市並沒有被夷爲平地。看到受災地照片我很震驚——不僅是被它們所呈現的受災狀況震驚，更被它們所無意呈現的，背景裏完好無損的建築所震驚。這一切似乎和缺乏約束的地震動預測圖(ShakeMap)相吻合，顯示爲7-8級烈度的近場地震，而非9-10級。

I’m thinking it will be an interesting part of the earthquake story, understanding the ground motions in the near field. There should be at least some strong motion data from Katmandu, and maybe elsewhere. It kills me there isn’t more: I tried to put together a proposal a few years ago to install more dense low-cost accelerometers in the valley, working with NSET [Nepal’s National Society for Earthquake Technology] and Tribuvan University. I was involved with a proposal that went in a year or so ago…. I do think preparedness efforts made a difference. Amod Dixit and his team at NSET have worked tirelessly on outreach, education, and training.

我想這會成爲地震史上對近場地動認知的有趣一幕。加德滿都應該至少有一些強烈地動的數據，也許其他地方也有。但只有這些，這讓我很煩惱：我試圖整合幾年前和尼泊爾國家地震技術科學會(NSET)和特里萬布大學(Tribuvan University)合作的一個在谷地更密集地安裝低成本測震儀的提案。我還參與了一年多前的一個提案……我認爲事先準備是有效可靠的。阿莫德·迪克斯特(Amod Dixit)和他在尼泊爾國家地震技術科學會的團隊一直孜孜不倦地在範圍、教育和訓練方面探索研究。

The population was not ignorant. Fatalism arises when problems are so far outside people’s control that they can’t do anything about it — or rather, they think they can’t do anything about it.

人們並非完全一無所知。但當問題超出可控範圍，人們無力迴天的時候，宿命論就會佔上風——或者說，人們自以爲無力迴天的時候。

And yes that paragraph is contradictory. The thing is, the overall problem was far outside anyone’s control but it is still possible to make some difference.

好吧，上一段的確很矛盾。關鍵在於，當整體問題完全失控的時候，我們依然是可以做出些改變的。

Port-au-Prince is mostly the same story: big problems, big earthquakes, few resources. By my calculation, ground motions in Port-au-Prince were not intensity 9-10, but maybe 6-8. The story again was vulnerability.

太子港的情況也差不多：問題棘手，地震嚴重，資源稀缺。據我個人計算，太子港地動烈度並非9-10級，可能是6-8級。那一次的問題，也是抗震能力。

I also asked her if there’s any concern about this being misperceived as the worst that could happen.

我還問了她此次地震誤解爲最嚴重的一次是否有什麼影響。

Could something bigger happen in Nepal? Sure.

尼泊爾會發生更嚴重的地震嗎？當然有可能。

There’s the megathrust segment immediately west of this earthquake, which we believe last broke in 1505. It’s the usual story, though: we don’t know when. The odds of subsequent big earthquakes always go up after a major earthquake. Ironically, the most dangerous time, statistically, is always just after a major earthquake has happened. But still it’s a low probability. We quote a 1-in-20 chance that something bigger will happen within 3 days, but the odds drop quickly with each passing hour. By this time [Sunday], the odds are more like 1-in-100. And the odds of an earthquake much larger than 7.8 are much lower still. It is possible, maybe even inevitable, that both Port-au-Prince and Nepal will be hit with stronger ground motions than what they’ve seen in recent years.

在地震發生地以西不遠處就有一個大地震破裂段，據信，其上次破裂是在1505年。但通常情況是這樣的：我們不知道它何時會破裂。隨後發生大地震的機率總是在一次嚴重地震發生後攀升。諷刺的是，數據表明，最危險的時候，總是在一次嚴重地震剛剛發生之後。但是概率還是很低的。一場更大的地震將在3日內發生的可能，我們在此引用1比20這樣一個機率，但是這種機率是逐小時迅速下降的。到現在（週日），這個機率大概是1比100。且發生一次遠遠強於7.8級的地震的機率比這還要低得多。太子港和尼泊爾都遭遇比近年來兩地所經受過的更爲強烈的地震，是可能的，甚至是不可避免的。

So the city of Katmandu, while still reeling, has clearly been spared what could have been a far higher death count given rapid urbanization in recent years (driven in part as people fled political turmoil in the hinterlands), poor quality of construction, lack of emergency services and other glaring issues.

所以加德滿都這座城市——儘管其還在經受重重餘震——鑑於其近年來迅猛的城市化進程（部分是人們逃離內陸政治動盪的結果）、差勁的建築質量、應急服務的缺失及其他顯而易見的問題，顯然幸運地避免了更慘重的傷亡。

The focus at the moment should be supporting rescue and relief efforts. But it’s also vital for Nepal and international aid agencies and organizations to redouble efforts to rebuild with the worse in mind.

此刻的重點應該是支持救援救災工作。但對尼泊爾和國際援助機構和組織來說，帶着最糟糕的預設去加倍爲重建努力至關重要。

The geological forces creating the earthquake hazard in Nepal and throughout the region are not abating, as Kenneth Chang wrote.

正如肯尼斯·張（Kenneth Chang，音譯）所寫道的，在尼泊爾及整個周邊地區造成地震災害的地質營力（指引起地質作用的自然力——編注）並未減弱。

Rural Devastation

滿目瘡痍的鄉村

Of course the other factor behind the low death counts so far is that estimates of deaths have mainly come from the capital and larger towns in the affected region, while small communities have been largely cut off.

當然，低死亡人數背後的另一個因素，是對於死亡人數的估計主要來自於首都和受災地區的其他較大城鎮，但小村鎮大多還處於人員無法進入的狀態。

Several earthquake analysts focused on the Himalayas said they would be surprised if the death toll ended up lower than 10,000 once rural towns and villages, hammered by landslides and building collapses, finish assessing losses. It could easily end up far higher.

關注喜馬拉雅山的幾位地震分析人士說，如果在遭受了山體滑坡、建築倒塌的農村鄉鎮和村莊完成傷亡評估後，死亡人數最終還低於1萬人，他們將感到驚訝。死亡人數很容易就會攀升至比這高得多的水平。

Scan Facebook or Twitter using these hashtags for affected villages to get the idea: #Sindhupalchowk #Gorkha #Nuwakot #Rasuwa #Dhading.

用這些標籤在Facebook或Twitter上檢索信息，來了解受災村莊的情況吧：#Sindhupalchowk #Gorkha #Nuwakot #Rasuwa #Dhading。（震前震後對比圖見圖一）

There has been a steady flood of appeals for help on social media, speaking of enormous, as-yet-uncounted losses. Here’s one, from the Facebook page of The Darjeeling Chronicle:

在社交媒體上，一直不斷出現着如潮涌般的求助信息，它們都是關於巨大的、到目前爲止還未被統計過的傷亡損失。這裏是來自《大吉嶺紀事報》(The Darjeeling Chronicle)Facebook頁面的求助信息（見圖二）。

Here’s a final thought from Thomas Parsons, also of the Geological Survey:

這是地質調查局的托馬斯·帕森斯(Thomas Parsons)的一個最後總結：

Unfortunately the tolls of this earthquake will likely rise with time as news from the more remote areas emerges. The intensity maps I’ve seen for Nepal are comparable to the M=7.6 2005 Kashmir earthquake (similar Himalayan foothills setting) where 80,000+ people perished. I don’t know anything about the population density in the strongest shaking zone in Nepal; hopefully it is lower than in the Pakistan case and construction standards are better (that’s just a hope, I don’t know).

很不幸，這場地震的死亡人數將很可能會隨着來自更偏遠地區的新聞報道漸漸出現而升高。我所見到的尼泊爾的強度分佈圖，堪比2005年克什米爾那場7.6級地震（類似的喜馬拉雅山腳下環境），逾8萬人在那場地震中喪生。我完全不知道尼泊爾地震最強烈的那個區域的人口密度是多少；希望它比巴基斯坦那個地震發生地的密度低、建築標準更高（這只是一個希望，我不知道這些信息）。

However, it appears that, other than some localized Katmandu basin effects, the city may have been spared from the most intense shaking. Had the earthquake been centered more to the east, this could have been substantially worse. In addition to possibly delayed reporting, we also have to worry about large aftershocks nearer to Katmandu (like the Darfield-Christchurch New Zealand example). Sometimes these can be delayed long enough to make improvements. For example, there were 5 years separating the 2008 M=7.9 Wenchuan China and 2013 M=6.6 Lushan earthquakes.

然而，看起來，除了一些局部的加德滿都盆地效應，這座城市可能躲過了最強烈的震動。要是震中往東移動一些，情況本可能糟糕得多。除了可能有延遲的報道，我們還應該擔心更靠近加德滿都的大型餘震（像新西蘭達菲爾德[Darfield]-基督城的那個例子）。有時，餘震會遲至已有足夠時間改善情況之後才發生。比如，中國汶川2008年的7.9級地震，與蘆山2013年的6.6級地震之間相隔了五年。

To get a sense (a chilling sense) of how popluation patterns have amplified exposure to earthquake hazards in the region, have a look at this map from GeoHazards International (a high-resolution version is here, part of a broader analysis), which shows the quake zone with population densities superimposed:

圖三可以幫助你理解（驚恐地理解）區域內的人口模式是如何擴大地震危害的。這張地圖來自地質國際（大圖請點擊這裏）同時標明瞭震區和人口密度：

If you missed it, here’s my initial post, shortly after the quake struck, noting that the entire Himalayan region faces an extraordinary danger from the conjunction of relentless tectonic activity, rapid population growth and vulnerable construction.

如果你沒有看到，這是我最初的文章，震後不久，我注意到整個喜馬拉雅地區面臨着由於版塊不斷運動、人口急劇增長及構造脆弱造成的巨大危險。