“放开二胎刻不容缓”——专访中国人民大学校长纪宝成 闲谈反省计划生育(五):瞒报女孩对统计数字有多大影响?
Apr 12

【此次预报事件之后,意大利、美国、德国英国权威地震研究机构的研究人员,都直言地震不能预报:Giuliani一方面没有准确预报,另一方面以往统计结果就是,氡气异常预报地震不可靠。唯独中国地震局的专家们集体失语,虽然他们早知道,根据中国的资料,水化学的漏报率是62%,中期预报的虚报率是81%,落实到临震预报则虚报率高达99%。原因无它,因为中国地震局预报队伍的日常工作,就是拿那些已经证明统计上和地震关系不大的“前兆”来“监测预报”地震。虽然徒劳无功,但是客观作用是安抚民心,主观作用是自己的饭碗所在,所以不好说破。】

Confusing Patterns With Coincidences

By SUSAN HOUGH
Published: April 11, 2009

Pasadena, Calif.

IN the aftermath of the earthquake at L’Aquila, Italy, on Monday that killed nearly 300 people, splashy headlines suggested that these victims didn’t have to die.

An Italian researcher, Giampaolo Giuliani, began to sound alarm bells a month earlier, warning that an earthquake would strike near L’Aquila on March 29. The prediction was apparently based on anomalous radon gas concentrations in the air; the region had also experienced a number of small tremors starting in mid-January. Mr. Giuliani was denounced for inciting panic by Italy’s Civil Protection Agency, and he was forced to take his warning off the Web after March 29 came and went without significant activity.

Should Italian officials have listened? Should the public have heeded the warnings? With 20-20 hindsight the answer certainly appears to be yes. The real answer is no.
【翻译:意大利官方应该听从(朱利安尼的预报)吗?公众应该按照警报行动吗?答案马后炮当然看起来是“应该”。正确的答案是“不应该”。】

Scientists have been chasing earthquake prediction — the holy grail of earthquake science — for decades. In the 1970s American seismologists declared that the goal was reachable. Yet we have little to no real progress to show for our efforts. We have a good understanding of the planet’s active earthquake zones. We’re pretty good at forecasting the long-term rates of earthquakes in different areas. But prediction per se, which involves specifying usefully narrow windows in time, location and magnitude, has eluded us.
【翻译:科学工作者追求地震预报——地震科学的圣杯——已经好几十年了。在1970年代,美国的地震研究者宣称这个目标能够实现。然而,我们尽管作出了努力,却几乎没有得到进展,或者没有真正的进展。对于地球的活动地震带,我们有很好的理解。对于不同地区长时间段地震发生的预测,我们做得不错。但是,对于地震预报本身,也就是指出明确的、能够实用的时间、地点和震级,我们做不到。】

The key question is, can we find precursors that tell us that a large earthquake is imminent? Various phenomena have been investigated: radon levels, changes in earthquake wave speeds, the warping of the earth’s crust, even the behavior of cockroaches and other animals.

The game goes like this: you look back at past recordings of X, where X is radon or whatever, and find that X had shown anomalies before large earthquakes. But the problem is that X is typically what we call a “noisy signal” — data that includes a lot of fluctuations, often for varied and not entirely understood reasons — so finding correlations looking backward is about as meaningful as finding animals in the clouds.

We do know that some earthquakes, including the L’Aquila event, have foreshocks, but we can’t sound alarm bells every time little earthquakes happen because the overwhelming majority — 95 percent or so — will not indicate a coming major quake.
【翻译:我们知道有些地震——包括这次阿奎拉事件——存在前震,但是我们不能在每次小震发生之后都按下警报,因为绝大多数的小震——95%左右——并不意味着将发生大震。】

The public heard about Mr. Giuliani’s prediction because it appears to have been borne out, albeit several days after he said the earthquake would happen. But there are scores of other predictions that the public never hears about. And that is a good thing because scientists have yet to be able to accurately predict coming earthquakes. Investigating precursors like radon is a legitimate avenue of research, but until and unless the track record of a method is shown to be statistically significant, making public predictions is irresponsible.
【翻译:公众听说了朱利安尼的预报,那是因为这个预报看起来验证了,尽管地震比他说的晚了几天。但是,还有很多其他的预报,公众从来没有听说过。幸亏没有听说过:因为科学工作者还做不到准确预报地震。研究氡气这样的前兆属于合理的研究途径,但是,除非(或者直到)以往记录表明某种方法存在统计意义,否则进行公开预报属于不负责任。】

Progress is slow in developing prediction methods, since, after all, they can be tested only by waiting for earthquakes to happen, and the earthquakes we care most about, like the deadly 6.3 magnitude quake in Italy, fortunately don’t happen every day. In the meantime, society’s keen interest in the subject occasionally collides with deliberative research, and misunderstandings like that involving Mr. Giuliani are the unfortunate consequences.

The public would like scientists to predict earthquakes. We can’t do that. We might never be able to do that. What people and government can do is work to make sure our houses, schools and hospitals don’t fall down when the next big one strikes, and that we’re all prepared for the difficult aftermaths. We can look around our homes and our workplace and think about what would happen to them if the terra firma suddenly ceased being firm. We can stop worrying about predicting the unpredictable, and start doing more to prepare for the inevitable.
【翻译:公众希望科学工作者能够预报地震。我们做不到。我们可能永远无法做到。公众和政府能够做的就是,下一次大地震袭来的时候,我们的房子、学校和医院不会塌下来,而且我们所有人都已经准备好了面对震后的困难。我们能做到查看我们的居家和工作场所,想一下如果稳定的大地突然不稳定了,这些场所会发生什么事情。我们能做到不再焦虑于预报不可预报的事情,而着手做更多的事情来应对不可避免的事情。】

Susan Hough is a geophysicist with the United States Geological Survey.

发表评论

CAPTCHA Image
*