GEOL 1425 1st Edition Lecture 14Outline of Last LectureI. Different MicroorganismsII. Microorganisms and their environmentsOutline of Current Lecture I. EarthquakesII. Points of an earthquakeIII. Seismic wavesCurrent Lecture- An earthquake occurs when rocks under stress fail along a geologic fault.- Elascity: the blocks would spring back and forth to their un-deformed, stress free shape if the fault were to suddenly unlock. - Distance of the displacement is the fault slip- Recurrence interval: time between ruptures. This should be constant and is calculated by dividing the fault slip in each rupture by the long term slip rate. - Focus: point at which fault slipping begins- Epicenter: geographic point on earth’s surface directly above the focus. - Focal depth of most earthquakes in continental crust range from 2-20 km.- In continental crust, earthquakes are relatively shallow because the lower they go, the plates act more ductile, not brittle material that snaps- Almost all large earthquakes trigger smaller earthquakes called aftershocks. The largest aftershock is generally 1magnitude unit smaller than the main shock.- Foreshock: small earthquakes that occurs shortly before a main shock near it’s focus. - Seismograph: reads seismic waves- 3 types of seismic waves, P waves, S waves, and surface waves.- P waves (primary waves): compressional waves, first wave to arrive, travel through solid, liquid, or gas and push or pull particles of matter in the direction of their path. - S waves (secondary waves): shear waves that place material at right angles to their path of travel. Can only travel through solids. - Surface waves travel through earth’s surfaceThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a
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