The Distribution of Hazards on a global scale.
The earth's crust is broken up into plates, the movement of the plates ninside the eath is called plate tetonics. Plate tetonics cause earthquakes and volcanoes. The point where two plates meet is called a plate boundary.Earthquakes and volcanoes are most likely to occur either on or near plate boundaries.
Earthquakes-What's the difference?
Focus- where the earthquake starts.
Epicenter- where the earthquake hits the hardest.
How are hazards measured and predicted?
A seismometer-detects vibrations made by an earthquake and plots them on a seismograph.
The strength or magnitude of an earthquake is measured in many different ways
Richter scale:0-10. This is the most common method. Measures the amount of energy released. 1 number = 10 times the size.
Mercalli scale: 1-12. Less known. Measured in roman numerals. Measures the amount of damage. Newer measure than richter.
Thermal imaging techniques to detect heat
Tiltmeter-measures how much bigger and how much movement a volcano has/is.
Conservative margins occur when two plates move sideways past each otherand land is neither formed nor destroyed. Here there can be violent earthquake activity, but no volcanic activity.
Examples; Pacific and North American Plates. eg. San Andrew and California.
Collision margins occur when two continental plates crusts collide and as neither can sink, are forced up into what we call 'fold mountains'.
Examples; Indo-Australian and Eurasian plates (eg.Himylayas).