【】

If you live in or close to New York City, your cellphone likely made a strange sound at about 8 a.m. this morning. The noise accompanied a special notification about the identity of the chief suspect in this weekend's Chelsea bombing, 28-year-old Ahmad Khan Rahami, with advice to call 911 if he's spotted.
SEE ALSO:This smart ring will alert emergency responders if you need helpThis is the wireless emergency alert (WEA) system in action. Rarely used, the system takes advantage of smartphone technology to push urgent alerts out to the public quickly. Considering smartphone penetration in the U.S. is about 80% of the population -- and most users carry their phones or have them nearby at all times -- the WEA system is arguably more effective at pushing alerts to the public than TV-based emergency broadcast system (EBS).
WEA basics
The system was first introduced in April 2012, and is most often used for severe weather and Amber alerts. Government agencies, both national and regional, decide when to issue them, and they typically do so only for situations that are "extreme, severe, immediate or imminent," an official with New York City Emergency Management told me after alerts went out during the blizzard of January 2015.
The Federal Emergency Management Agency (FEMA) has final say over which agencies have access to the WEA system, according CTIA, an U.S.-based industry coalition of wireless carriers.
Once an agency decides to send out alert, it's pushed out via the wireless carriers. For most carriers, the alerts will sound on customers' phones within minutes or even seconds, and, although the alerts go out over their networks, the carriers have no say in whether or not they go out (technical glitches notwithstanding). However, the carriers' participation in the WEA system is voluntary, according to the FCC's FAQ page on WEAs.
To WEA or not to WEA
The alert about Rahami appears to be the first time the system has been used as a digital wanted poster, at least in the New York region. However, in the aftermath of the 2013 Boston marathon bombings, law enforcement issued an alert to city residents advising them of the manhunt for then-suspect Dzhokhar Tsarnaev and to "take shelter."
There are three types of scenarios for WEAs: local emergencies (including weather and law-enforcement situations), Amber alerts and directives from the President of the United States. Smartphone users can opt out of the first two but not the third.

If you wish to opt out of WEAs, on iOS, go to Settings, then Notifications. Scroll all the way to the bottom, and you'll see "Government Alerts." From there, simply tap the toggles of the alerts you don't want.
On Android, the opt-out procedure varies, with some phones having a specific notification setting for turning off the alerts and others that you make the change from the phone's default messaging app. You should contact your carrier or phone's manufacturer if you have difficulty finding the setting.
What the alerts are
The alerts are not technically SMS text messages. Although they go over carrier networks, they use a separate technology that "will not get stuck" if wireless traffic is congested in the region -- often a problem in an emergency situation. They're limited to 90 characters, CTIA says, and don't appear to have any way to attach multimedia -- hence the advisement to "See media for pic" in the Rahami alert.
If commuters weren't already on edge today, this alert which just rang through the entire train got us there. pic.twitter.com/RHAvTw0mlh
— Lance Ulanoff (@LanceUlanoff) September 19, 2016
WEAs will override the volume controls of your phone, chiming with the emergency broadcast signal for several seconds. In practice, it means several phones in a place -- a subway car, restaurant or busy street corner -- will suddenly make the same sound, which can happen several times, depending on when individual carriers issue the alerts.
While eerie, that effect is precisely the point. When a government agency issues a WEA, it's to make sure the public is aware of an emergency situation that may require immediate action.
相关文章
'The Flying Bum' aircraft crashes during second test flight
Airlander 10, the world's largest aircraft, on Wednesday crashed at its Cardington Airfield base in2025-04-24- 燙麵炸糕最正宗配方?將涼水用旺火燒沸後,點上少許涼水,倒入同樣多的麵粉,迅速攪拌,直至麵團變成灰白色2/5到了不粘手時,取出攤在案板上晾涼3/5麵團中加入老酵和堿麵揉勻 。正宗燙麵炸糕如何製作?燙麵炸糕2025-04-24
- 椒鹽龍頭魚做法?材料:新鮮龍頭烤 、蔥薑 、生粉或吉士粉、料酒 、鹽 、椒鹽粉做法:1龍頭烤去頭去腸洗淨,用蔥、薑 、鹽 、料酒醃製15分鍾以上2醃製後的龍頭烤濾去水,周身拍上生 。椒鹽龍頭魚的做法竅門-業百科用料2025-04-24
- 兒童水晶泥怎麽玩?模具玩法:提升寶寶思維能力用不同顏色的水晶泥填充入印膜內,也可以取水晶泥平鋪在在用空心印膜印出圖案 。搭配小模具 。2、吹泡泡玩法:提高寶寶動手能力先將 。怎樣正確使用水晶泥?4、等到攪拌2025-04-24
The U.S. will no longer have the final say on internet domain names
The National Telecommunications Information Admistration (NTIA) announced via 。 blog post。on Tuesday2025-04-24- 男襯衫上寫的39是多大的碼?40 、38,41是多大的?歐碼M=男女身高165/170,男襯衫領圍39 。歐碼L=男女身高170/175,男襯衫領圍40 。歐碼XL=男女身高175/180,男襯衫領圍41。2025-04-24
最新评论