earthquk - Earthquakes What is an earthquake? Causes of...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Earthquakes What is an earthquake? Causes of earthquakes (Fig. 1) Stress buildup causes a new fault Stress buildup causes movement on an existing fault plane. Definitions: Seismic wave Seismology Earthquake focus (Fig. 1) Earthquake epicenter (Figs. 1, 2) Recording earthquakes Seismographs: (Fig. 3) Seismograms (Fig. 4) Seismometers Types of seismic waves Body waves (i) Primary waves: 6 - 7 km/sec; compression and dilation (Fig. 5) (ii) Secondary (shear waves): 3.5 km/sec, particles move perpendicular to the direction of wave motion (Fig. 6) Longitudinal (surface waves): up and down + side to side movement; drag + shear!, slowest. Intensity of earthquakes Mercalli intensity scale Magnitude of earthquakes Richter's scale: For a Wood - Anderson type seismograph located ~ 100 km from epicenter in California (or where the rocksaffected are similar to those in California), the magnitude of an earthquake "M" according to this scale, is given by a formula similar to: M = log (A . 10 4 ) where A is the amplitude (in mm) of the largest wave on a seismogram. However, the
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/27/2012 for the course GEOLOGY 110 taught by Professor Staff during the Fall '08 term at Marshall.

Page1 / 3

earthquk - Earthquakes What is an earthquake? Causes of...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online