,
13 tweets,
3 min read
Read on Twitter
I don't usually all-caps but I'm going to. NO ONE CAN PREDICT EARTHQUAKES. We just can't do it. The difference between a prediction and a forecast is essential. We (scientific community) *can* forecast aftershocks--quakes that come after a mainshock (main earthquake). See link:
Prediction: Say the time, place, magnitude (when, where, what/how big). We *cannot* do this for #earthquakes. If someone claims to know any of these three things, it is unfounded.
Forecast: Probability. We *can* do this, to an extent, and are working to get better. How likely is an event? We can use math for that. ... But nothing is certain.
After a big earthquake, aftershocks (associated earthquakes, along the same fault) are likely. We can put a number on that based on our current knowledge. But we can't say exactly *when* they will occur, exactly *where* they will occur, or exactly *how big* they will be.
A good analogy I've heard: You go to the doctor because you're sick. You have a cold. The doctor may tell you you are likely to cough, and what to expect from the coughing, but not exactly when you will cough or exactly how hard. Similar for earthquakes & other earth processes.
Why even both to go the doctor? Because the more we know about sickness, the more we can take measures to prevent it, prepare for it, & alleviate it, and know what to expect from it (we don't like uncertainty, so we can at least reduce it). Same with natural hazards.
A note on earthquake early warning: It is not a prediction, it is a detection system. Here's how it works: [thx @babbittnbromide for the prompt & & @EricFielding for that wording)]
An earthquake happens. No warning ahead of time. Its waves are detected by nearby instruments. With enough data, the system quickly calculates where and when the earthquake happened, and with a little more time how big it was.
Then the system sends out a warning to areas within the area likely to experience damaging shaking. Areas very close to the earthquake will not get the warning before they feel the shaking, but areas far enough away for the system to detect, calculate, and issue the warning will.
The max warning populations are likely to have before damaging shaking is about 2min. The amount of time they have depends how far they are from the source (earthquake).
Even with less than two minutes, infrastructure tied into the system can be automatically shut down, e.g., elevators stopped at nearest floors and trains stopped.
This also gives people, with practice, time to respond. Drop, cover, and hold on. The most visceral example of a response I've heard is that surgeons can put down their tools. Even a short amount of time can make a big difference.
Again, to be clear, earthquake early warning is *not* prediction. It's a response system for an earthquake once it has happened. The waves take time to propagate, and we can use that short time to prepare for shaking.
