Earthquakes and your farm – that seems a strange topic, but having a little knowledge could save your life, reduce injuries and minimize the risk of damage to you homestead.
Earthquakes primer – what is an earthquake?
The rocks in the Earth’s outer layer (the crust) are under constant pressure – they are either being squashed or pulled apart. These massive stresses occur due to the slow but steady movement of huge slabs of rock (plates) around the planet in a process that geoscientists call Plate Tectonics.
Occasionally the rocks under all this pressure break and/or slide past (more like grind past each other) along zones we call faults. It is the breaking and grinding that releases vast amount of energy which travel as waves through the rock. This energy is what we call an earthquake.
The vast majority of earthquakes occur below ground. The actual point on a fault where the break occurs is called the focus of the earthquake. The point on the ground’s surface directly above the focus is called the earthquakes epicenter. Sometimes the focus is right at the surface, and so the focus and the epicenter are the same place.
When an earthquake takes place the energy moves as waves through the rocks away from the focus. It is these waves that shake, rattle and roll buildings causing damage. The waves are strongest closest to the focus and weaken as they move away from the focus.
It is also the strength of these waves that allow scientists to assign a strength, or magnitude (M), to an earthquake. The scale of strength was first developed by a guy called Richter for earthquakes in the California area – the famous Richter Scale. However modern earthquake science just calls it a “Magnitude”.
The vast majority of Earthquakes are too small to cause damage, and most are only recorded by sensitive instruments (Magnitude 1-2).
People start to feel earthquakes (and recognize that it was an earthquake) around magnitude 3.
Magnitude 5 and above earthquakes may start to cause damage to buildings – especially poorly constructed ones close to the epicenter. Magnitude 6 earthquakes can topple chimneys and crack plaster ect. Magnitudes above that cause considerable damage and anything over a magnitude 8 is catastrophic.
I hope you never experience strong earthquakes on your farm!
Scientists use a separate scale called the Modified Mercali Scale to record eyewitness accounts of the earthquakes effects – what did people feel? What damage did it cause? etc. It uses a scale (I-XII) based on the level of damage. If you ever feel an earthquake you can go online and provide scientists with extremely valuable information. Here is the link.
Earthquakes and your farm
There are three things that you can do about earthquakes and your farm.
1. Know what the risk is for you area. There are maps that are developed by your countries geological agencies that show earthquake risk. They can be complex, but the important thing to know is that (generally) the red zones will get more earthquakes than the green zones.
Another way is to look at the recent earthquakes for your area. This Map of recent Earthquakes (USGS) is wonderful. Zoom in/out to find your location. Click on the dots to get more information about the earthquakes.
2. Prepare your farm based on the risk. If you are in a high risk zone, then you should do things around your homestead to make it safer in a strong earthquake. Your local authorities – like emergency rescue – will have information on what to do to prepare. This might be securing book shelves better to the wall to stop them tipping over the having tools hanging in loops in your workshop. Hunt down the information and get your place ready. Here is the list of USA FEMA publications on earthquake preparations.
And here is the USGS booklets (english and spanish) on ‘Putting down roots in Earthquake country’.
3. Know what to do in an earthquake. You may be at home…but you could be visiting…so know what you need to do in an earthquake. Here is a great guide.
But a quick guide….
- If you are inside – don’t run outside! Get away from windows and get under a sturdy table or bed. If there is no table, get in an internal doorway. Cover your head and face and wait for the shaking to stop.
- If you are outside, get away from buildings/structures and overhead wires – cause they might fall over. Sit down and wait for the shaking to stop.
- If you are driving – stop the car in an open area and wait for the shaking to stop.
- If you are on the coast – move to higher ground. This is in case the earthquake generates a tsunami.
Earthquakes and your farm? – the thing is to be prepared and know what to do! Make sure your children know what to do as well 🙂 Run a practice earthquake drill (its fun).