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Science and Technology Policing The aftershocks of crime
科技 治安 犯罪余震
An idea borrowed from seismology may help to predict criminal activity
從地震學上獲取的靈感或許能預測犯罪行為
LOS ANGELES is one of the most under-policed cities in America. With a mere 26 officers for every 10,000 residents (Chicago, by comparison, has 46), the Los Angeles Police Department (LAPD) needs all the help it can get.
洛杉磯是美國警力最不足的城市之一，每一萬個市民只分配了26名警察（相比之下，芝加哥是46名），因此洛杉磯警局急需各方支援。
That help may be at hand, with a modification of technology used to predict another type of threat that the city is prone to: the aftershocks from earthquakes. Big earthquakes are unpredictable. Once they have happened, however, they are usually followed by further tremors, and the pattern of these is tractable.
支援也許就近在咫尺，只要將一項技術修改一下便可。這項技術原本是用來預測余震的——這個城市很容易受到的另一種災難。大地震是無法預測的，但是大地震發生后隨之而來的余震模式卻是可以掌控的。
George Mohler, a mathematician at Santa Clara University, in California, thinks something similar is true of crimes. There is often a pattern of "aftercrimes" in the wake of an initial one. The similarity with earthquakes intrigued him and he wondered if the mathematical formulas that seismologists employ to predict aftershocks were applicable to aftercrimes, too.
加利福尼亞州的圣克拉拉大學的數學家喬治·默赫勒（George Mohler）認為，余震和犯罪有著相似之處。在初始犯罪后，常會尾隨一種"犯罪后效應"模式。這種和地震的相似性激起了他的興趣，于是他想，如果地震學家應用的預測余震的數學公式應用到犯罪后效應中，又會如何呢？
To test this idea, he and a team of researchers from the University of California, Los Angeles, adapted a computer program used by seismologists to calculate the likelihood of aftershocks. They then seeded it with actual LAPD data on 2,803 residential burglaries that occurred in an 18km-by-18km region of the San Fernando valley, one of the city's largest districts, during 2004. Using the seismological algorithms, the computer calculated which city blocks were likely to experience the highest number of burglaries the next day, and thus which 5% of homes within the area were at particular risk of being broken into. In one test the program accurately identified a high-risk portion of the city in which, had it been adequately patrolled, police could have prevented a quarter of the burglaries that took place in the whole area that day.
為了測試這一想法，他和一隊來自加利福尼亞大學的研究人員采用了一套地震學家用來計算余震可能性的電腦程序，輸入了2004年，在圣費爾南多谷（洛杉磯最大的區之一）中面積為18*18km2的區域里發生的2803起住宅爆竊案的警方數據。通過地震學的運算法則，電腦計算出了哪些街區在第二天可能會遭到大批盜竊，因此區域內5%的住宅都冒有很大被盜的風險。在一項測試中，這個程序精確地辨識出了該市的一塊高風險區，而如果巡邏充足，警方本可以在那一天阻止該地區四分之一的盜竊案。
In addition to modelling burglary, Dr Mohler examined three gang rivalries in Los Angeles, using data from 1999 to 2002, and discovered that similar patterns emerge from gang violence as retaliations typically occur within days—and metres—of an initial attack. That, too, should help police deploy their limited resources more effectively. RoboCop move over, then. ComputerCop is coming.
除了用盜竊案做模型，默赫勒用1999到2002年的數據，也檢測了三起洛杉磯的幫派斗爭，并發現了相同的模式：在最初的襲擊之后，幾天內會在鄰近區域很典型地發生復仇暴力。這也能幫助警方更有效地部署有限的資源。機器戰警（《機器戰警》是一部1987年的科幻片——譯注）已經過時，現在是電腦戰警的時代了。
