11186928
Description
Flashcards by Caitlin McFadyen, updated more than 1 year ago
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Created by Caitlin McFadyen
about 7 years ago
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| Question | Answer |
| Primary Seismic Waves | Fast travelling; low frequency; compressional waves - they vibrate in the direction they travel |
| Secondary Seismic Waves | Half the speed on Primary waves; high frequency waves - they are further reaching and therefore less intense. They vibrate at right angles |
| Surface Seismic Waves | Slowest of the waves; low frequency - some have a rolling movement that moves the surface vertically while others move the ground at right angles to the direction of movement |
| Depth of focus: Shallow focus | Surface down to about 70km; very often and don't give off much energy; very small (usually an earthquake of 2 on the Richter scale) |
| Depth of focus: Deep focus: | 70-700km. Much larger bursts of energy, far more powerful and usually a 6 on the Richter scale |
| What is the Richter scale | It measures the magnitude of an Equake, the amount of energy that a EQ gives out - the initial burst of energy that gives out from the focus |
| The Richter scale uses a Logarithmic scale - what is this? | Each whole number increase in magnitude represents a ten-fold inc in the amplitude of the wave - there is no limit to the scale, the highest one recorded was Japan 2011 (9 on the scale) |
| What is the Modified Mercalli scale | This measures equake intensity and its impact; a qualitative assessment based on observation and description. Its not really used or referred to |
| What is the Modified Magnitude scale (Mw) | Measures the energy released by the equake more accurately than the Richter scale. Energy released = related to geographical properties such as rock rigidity, area of the fault surface and amount of movement on the fault. Only measures larger scale equakes as it uses the amount of physical movement. |
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