TABLE OF CONTENTS The following notation is used in this chapter:
| SYMBOL | DEFINITION | |
| a max | Maximum horizontal acceleration at the ground surface (also known as the peak ground acceleration) | |
| A | Maximum trace amplitude recorded by a Wood-Anderson seismograph | |
| A ? | Maximum ground displacement in micrometers | |
| A f | Area of the fault plane | |
| A 0 | Maximum trace amplitude for the smallest recorded earthquake (A 0 = 0.001 mm) | |
| D | Average displacement of the ruptured segment of the fault | |
| g | Acceleration of gravity | |
| M L | Local magnitude of the earthquake | |
| M 0 | Seismic moment of the earthquake | |
| M s | Surface wave magnitude of the earthquake | |
| M w | Moment magnitude of the earthquake | |
| ? | Epicentral distance to the seismograph, measured in degrees | |
| | Shear modulus of the material along the fault plane |
The theory of plate tectonics in the 1960s has helped immeasurably in the understanding of earthquakes. According to the plate tectonic theory, the earth s surface contains tectonic plates, also known as lithosphere plates, with each plate consisting of the crust and the more rigid part of the upper mantle. Figure 2.1 shows the locations of the major tectonic plates, and the arrows indicate the relative directions of plate movement. Figure 2.2 shows the locations of the epicenters of major earthquakes. In comparing Figs. 2.1 and 2.2, it is evident that the locations...
