Earthquake Early Warning

The US Government is testing an early warning system for earthquakes, which could buy vital seconds of time in advance of a major incident. For years the US has lagged behind Japan in quake detection technology and it is hoped that this latest system will bring it in line with other quake-prone countries.

Our reporter Li Dong has the details.

 
A map of California with a flashing red dot shows the epicenter of an earthquake. A clock counts down the time remaining before the earthquake strikes and another warning predicts the expected magnitude. The shock waves fan out like ripples¹ on a pond across the state of California.

If this pops up on your desktop² at work then you've got just seconds to react... But those seconds could be the difference between life and death.

At the moment the system is still in its development stages, and has not yet been broadcast to California's residents or businesses; but it does represent the future.

With more testing and funding, researchers hope to build a public warning system similar to the Japanese networks credited with saving lives during the March 11 magnitude-9 disaster.

Since earthquakes are unpredictable, supporters of early warning systems say it's the next best thing available to prepare people and businesses before the ground shakes. Even an advance notice of five seconds can be precious.

Doug Given, of the US Geological Survey explains the importance of an early warning system ... even if it is just a few seconds.

"What can you do with a few seconds warning? The most obvious for the average citizen is to drop, cover and hold on."

Early warning systems are designed to sense the first pulses of energy after a fault breaks and use this to estimate the magnitude of the quake. This is possible because of the different speeds at which seismic³ waves travel.

A sprawling⁴ web of underground sensors⁵ can detect the faster-moving and less damaging primary "P" waves before the secondary "S" waves hit, which can cause buildings to collapse⁶. Doug Given says this is how a warning is issued, ahead of the arrival of these stronger waves.

"So, if you can detect the earthquake very quickly as it begins, you can send warning ahead of the most damaging waves."

But how much warning? Doug Given says the warning could be just a few seconds to tens of seconds; it all depends on the distance from the epicenter. The farther away an area is, the more notice people in that area will receive.

"Depending on your distance from the earthquake, you get from zero up to a minute's warning."

A number of actions can be taken in advance of a quake striking - trains can be slowed or stopped; air traffic controllers can halt takeoffs and landings; power plants and factories can close valves; and schoolchildren can dive under their desks and cover their heads.

Early warnings are useless at the quake's origin because the tremors⁷ radiate out almost simultaneously⁸.

But there have been glitches⁹ in the system. Sensors underestimated a quake at a magnitude 8.1 when it was actually 22 times stronger.

Because of the error, warnings were not sent to certain cities. The jolt¹⁰ was so violent that it knocked 55 seismic stations offline and there were no warnings sent for aftershocks for several hours.

Since 2006, the U.S. has been testing three alert systems and launched a prototype internally known as "ShakeAlert" in February, a month before the Japan devastation¹¹.

For now, messages are only blasted out to about 30 scientists at the USGS, California Institute of Technology and University of California, Berkeley, where they are ironing out software bugs¹² on a small budget.

For CRI, I am Li Dong.

1 ripples   

逐渐扩散的感觉( ripple的名词复数 )

参考例句：

• The moon danced on the ripples. 月亮在涟漪上舞动。
• The sea leaves ripples on the sand. 海水在沙滩上留下了波痕。

2 desktop   

n.桌面管理系统程序；台式

参考例句：

• My computer is a desktop computer of excellent quality.我的计算机是品质卓越的台式计算机。
• Do you know which one is better,a laptop or a desktop?你知道哪一种更好，笔记本还是台式机？

3 seismic   

a.地震的，地震强度的

参考例句：

• Earthquakes produce two types of seismic waves.地震产生两种地震波。
• The latest seismic activity was also felt in northern Kenya.肯尼亚北部也感觉到了最近的地震活动。

4 sprawling   

adj.蔓生的，不规则地伸展的v.伸开四肢坐[躺]( sprawl的现在分词 )；蔓延；杂乱无序地拓展；四肢伸展坐着（或躺着）

参考例句：

• He was sprawling in an armchair in front of the TV. 他伸开手脚坐在电视机前的一张扶手椅上。
• a modern sprawling town 一座杂乱无序拓展的现代城镇

5 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

6 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

7 tremors   

震颤( tremor的名词复数 )； 战栗； 震颤声； 大地的轻微震动

参考例句：

• The story was so terrible that It'sent tremors down my spine. 这故事太可怕，它使我不寒而栗。
• The story was so terrible that it sent tremors down my spine. 这故事太可怕，它使我不寒而栗。

8 simultaneously   

adv.同时发生地，同时进行地

参考例句：

• The radar beam can track a number of targets almost simultaneously.雷达波几乎可以同时追着多个目标。
• The Windows allow a computer user to execute multiple programs simultaneously.Windows允许计算机用户同时运行多个程序。

9 glitches   

n.小过失，差错( glitch的名词复数 )

参考例句：

• Manufacturing glitches have limited the factory's output. 生产中的故障影响了该厂的产量。 来自辞典例句
• Another kind of period variation,\"Glitches,\" are seen in several pulsars. 在几个脉冲星中还看到了周期的另一种变化，即“自转突快”现象。 来自辞典例句

10 jolt   

v.（使）摇动，（使）震动，（使）颠簸

参考例句：

• We were worried that one tiny jolt could worsen her injuries.我们担心稍微颠簸一下就可能会使她的伤势恶化。
• They were working frantically in the fear that an aftershock would jolt the house again.他们拼命地干着，担心余震可能会使房子再次受到震动。

11 devastation   

n.毁坏；荒废；极度震惊或悲伤

参考例句：

• The bomb caused widespread devastation. 炸弹造成大面积破坏。
• There was devastation on every side. 到处都是破坏的创伤。 来自《简明英汉词典》

12 bugs   

adj.疯狂的，发疯的n.窃听器( bug的名词复数 )；病菌；虫子；[计算机]（制作软件程序所产生的意料不到的）错误

参考例句：

• All programs have bugs and need endless refinement. 所有的程序都有漏洞，都需要不断改进。 来自《简明英汉词典》
• The sacks of rice were swarming with bugs. 一袋袋的米里长满了虫子。 来自《简明英汉词典》