A cartoon about twitterers and earthquakes leads to a brief peek at earthquake warning systems.
Cartoonist xkcd throws humour on twitterers and their reportage of earthquakes:
Would an automatic response to recording equipment determining an event of a particular magnitude reduce the 20-30 second delay to twitter the message (or broadcast a text to cellular phones) so that the messages might out-pace earthquakes at closer distances?
Are there automated warning systems out there?
I don’t really have an answer to the first question but there are certainly notification systems. Are these fast enough to warn people in advance so that they might take evasive action?
According to this press release from the U.S. Geological Survey (USGS):
Earthquake early warning systems, already successfully deployed in Mexico, Japan and Taiwan, can detect an earthquake in progress and provide notice of seconds to tens of seconds prior to actual ground shaking.
This press release doesn’t say how far away you’d from the epicentre of the earthquake you’d need to be for the warning to be in advance.
The video interview below gives some background on the Japanese system. From about 2 minutes into this interview an example is given of a magnitude 6.8 earthquake 200 kilometres north of Tokyo giving about 3 seconds warnings of the event in Tokyo.
Besides alerting people, automated warning systems could potentially stop trains, elevators, switch off gas services and so on.
Warnings can be distributed many ways including radio, the internet, cell phones and pagers. In Japan they also appear on television as this video of the 2008 Iwate-Miyagi Nairiku earthquake warning broadcast shows (with English subtitles). It’s an eerie feeling to see the announcer say that there is time before the event occurs, it’s got a little of the unreality of a Doctor Who forecast!:
In New Zealand possible earthquakes are notified to a GeoNet duty officer. If the event is considered ’big’ enough to be worthy of public notification, a preliminary announcement is published on the GeoNet website. This usually occurs within 30 minutes. These events are also reported by a number of other services available via GeoNet’s subscription page.
There are email options; people in low-lying areas can check out subscribing to the tsunami warning emails.
Via GeoNet’s Hazard Alerts options is a service to subscribe to receive alerts by cellular phone or pager. Emergency services such as the Civil Defence as subscribed to this for free; mere mortals need to apply and pay (at the time of writing $30 per month per pager or cell phone user). The application form can be obtained as a PDF file. With an appropriate phone, you receive a map indicating the focus of the earthquake.
To @BadAstronomer for the cartoon. Via twitter, what else?
Many thanks to Jennifer from GeoNet whose replies to my emails were very helpful. (In case anyone is wondering, I’ve no idea of her surname, her email signature doesn’t offer it!)
I am not a geologist; this is reportage, not an expert’s take on the subject.
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