California to Develop Earthquake Early Warning System
Californian officials say they will spend more than $40 million on an earthquake early warning system.
The announcement comes after two powerful earthquakes shook parts of the state last week. On Thursday, a 6.4-magnitude earthquake struck an area in the Mojave Desert, but the effects could be felt as far away as Los Angeles. Then on Friday, a 7.1-magnitude earthquake struck near Ridgecrest, California, causing damage to houses and roads.
The proposed early warning system would let the public know of a possible quake. Officials say it also would automatically halt trains and open fire station doors moments before a major quake strikes.
California Governor Gavin Newsom made an announcement after Friday's quake. He said that the state has already put in place 70 percent of 1,115 sensors needed for a statewide system.
Ryan Arba is with the governor's Office of Emergency Services. He said, "I think the whole state's on notice right now about the opportunity that's in front of us."
Emergency officials have said they hope to have the statewide warning system in place by the middle of 2021.
The recent strong earthquakes were the first in 20 years in Southern California. They brought increased attention to the development of the state's early warning system.
Japan developed the world's most modern earthquake early warning system after the 1995 Kobe earthquake. It relies on more than 4,000 sensors and is based on the same laws of physics that California is using to build its system.
P-waves can provide early warning
As in Japan, the California system is designed to detect the fast-moving seismic P-waves that are produced by earthquakes. These waves can reach a sensor before the ground starts moving. The U.S. Geological Survey says that many animals are able to feel P-waves.
Communities farthest from the epicenter of a quake would receive the earliest warning.
Arba says, for example, that a quake on the San Andreas Fault near California's border with Mexico would give Los Angeles 60 seconds of warning before the ground began to shake there. However, communities very close to a quake's center would receive little or no warning.
Officials in Los Angeles County in January introduced a "ShakeAlertLA" mobile phone application. It can send an early warning to residents who have the app. The "ShakeAlertLA" app, however, was not activated for either of the recent quakes. The U.S. Geological Survey said this was because they were not strong enough.
Trains at risk during earthquakes
The Bay Area Rapid Transit (BART) system in and around San Francisco has connected the early detection system to its rail service. The system is designed to automatically slow down trains, Arba said.
Southern California's Metrolink commuter rail system halted service after Friday's 7.1 earthquake in Ridgecrest. But, a spokesman said orders to stop the trains only went out by radio when shaking was felt by officials at the operations center in Pomona, east of Los Angeles.
The Metrolink board has voted to spend $4.9 million in public money to automate the halting of its trains when a quake is detected, the spokesman said.
University of California at Los Angeles engineering professor John Wallace said there are many possible uses for the early warning system.
"Once you provide the system, you'd be surprised how many ways people will find to use it," he said.
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1.at risk 处于危险中
The crisis could well place the relationship at risk.
2.slow down 减速
The car slowed down as they passed Customs.
3.public money 公款
Most of the public money went to maintaining roads.
4.early warning system 早期预警系统
Early warning system of monetary crisis is an important component of the financial security construction of a country.
5.He said that the state has already put in place 70 percent of 1,115 sensors needed for a statewide system.
put in place 落实到位
They're offended by the elaborate security measures the police have put in place.
The restrictions have been put in place, after a five-day national strike.
6.On Thursday, a 6.4-magnitude earthquake struck an area in the Mojave Desert, but the effects could be felt as far away as Los Angeles.
as far away as 远达
He had gone as far away as possible to build a new life.
They came from as far away as Florida.
该消息公布之前，上周加州部分地区发生了两次强烈地震 。周四，莫哈韦沙漠发生了一场6.4级的地震，但是远到洛杉矶都有震感 。
拟议的预警系统能通知公众有可能发生的地震 。有关官员说，该系统还能在地震发生前瞬间自动停止运行的火车和打开消防局的大门 。
加州州长加文·纽森（Gavin Newsom）在周五的地震后宣布了这一消息 。他说，加州全州系统所需的1,115个传感器安装已经完成了70％ 。
瑞恩·阿尔巴（Ryan Arba）任职于州长紧急事务办公室 。他说，“我认为整个州现在都在关注摆在我们面前的这个机会 。”
最近发生的地震是南加州时隔20年来发生的首次地震 。这些地震让他们更加关注全州预警系统的发展 。
1995年神户大地震后，日本开发出了全球最现代化的地震预警系统 。该系统依赖于4,000多个传感器，其系统与加州构建预警系统的物理定律相同 。
与日本一样，加州的地震预警系统可用于探测地震产生的快速移动的地震纵波 。这些波会在地面开始移动前抵达传感器 。美国地质调查局表示，很多动物都能感知地震纵波 。
阿尔巴说，加入加州与墨西哥边境附近的圣安德烈亚斯断层发生地震，预警系统可在地面震动前提前60秒向洛杉矶发出预警 。然而，非常靠近震中的社区收到预警的时间较短，或者是收不到预警 。
1月份，洛杉矶县官员推出了一款“洛杉矶地震预警”手机应用程序 。它可以向安装应用的居民发送预警 。然而，“洛杉矶地震预警”应用程序在最近的两次地震中都没有反应 。美国地质调查局说，这是因为震级不够大 。
旧金山及其周边的湾区快速交通（BART）系统已经将地震预警系统与铁路服务联系起来 。阿尔巴表示，该系统目的是让列车自动减速 。
周五里奇克莱斯特发生7.1级地震后，南加州的捷运通勤铁路系统暂停运营 。但是一位发言人表示，停运指令是在洛杉矶东部波莫纳运营中心的官员感知震动后才通过无线电发出的 。