Page 205 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

- Crust
187 by (or focus Earth Earth’s epicen- because Focal earth- earth- focus extends Boundary a) Only crust and uppermost

Earthquakes described be The 7.2). the within on point the from Earth, the failure. brittle Most 7.3). focus shallow deep all lithosphere Plate Asthenosphere

of can (Fig. volume) the is distance of km undergo (Fig. depth; virtually where Transform _- Crust
Characteristics earthquake rupture small epicenter the is 700 upper can boundary km 70 and depth) settings, b) Boundary

of an of zone (relatively The depth the which plate of to km 7.3c). Plate
location the of released. The focal in occur lithosphere, type surface boundaries. 300 to (subduction) (Fig. mantle are cold and brittle enough to produce earthquakes along divergent boundaries. b) Earthquakes occur in the upper (cold) part of the lithosphere at transform boundaries. c) At convergent boundaries, shallow earthquakes occur in the upper plate due to compression. zone of shallow to de

The depth and “point” actual is energy focus. the Earthquakes rigid the to related the from of plate (70 focus convergent asthenosphere Boundary _/ Crust Convergent c) Positions and depths to earthquakes (black dots) along different types of plate boundaries,

Earthquakes Epicenter and longitude, the is earthquake above directly focus. Depth the to confined normally focus, shallow types all at intermediate in occur the through Plate Asthenosphere

of Focus latitude, hypocenter) the where surface the to Focal are are depths are quakes occur quakes Most earthquakes deeply Divergent J
Location the ter they a) 7.3 A

FIGURE

through earth- be must and Other fluidly, lower to to the near Law, it fashion, released off sends Stress view of a

be in there limit; and The subjected confined Hooke’s is Relieve and depth
could results 1) elastic lithosphere. ductilly time. of not exclusively concentrated brittle energy which fault, or cross-sectional Rocks initially behave elastically as

failure situation necessary: its beyond the is behave periods are they are obeying a in strain earthquake, Rebound to (Fig. 3.1c). If brittle failure occurs, stored energy is Cross section of a rupturing fault, illustrating terminology location

limit, latter thus criteria long but stresses stressed, fails rock stored an —_c) to new positions across the fault, seismic waves radiate from the as 7.2 to describe the

elastic its The 3.2). are factors material the above the core, outer over applied solid, are are, therefore, almost where be can rock the If 3.1c). the as is energy Elastic Limit 5 ee Feut either map view of a strike-slip undeformed state. b) i FIGURE used of an earthquake.

Seismology EARTHQUAKES beyond stressed 3.1, (Figs. fracture two occur, to stress will that fracture. brittle fits that Earth and asthenosphere are stresses core inner the Earthquakes particularly that states (Fig. limit position new strain of release Stressed to represent rocks is reached of the ek nv cP Earth's

Earthquake OF Theory is material brittle or earthquakes movement by fail must the of region the as large when and (mesosphere) stresses. lithosphere, rigid of plates. theory rebound elastic its a into (snaps) sudden waves. seismic b) Elastic rebound. Figure can fault. a) Sequence of rocks in (Fig. 3.1b).c) Elastic limit earthquake. rocks rebound The focus). €? wee

Chapter7 CHARACTERISTICS Rebound Earth When flow ductile For quakes. of sort some material the The such regions, respectively, mantle differential large moving, the boundaries Elastic reaches it until rebounds The 7.1). (Fig. as vibrations Undeformed Rocks or reverse) rupture zone (earthquake

186 Elastic 2) 7.1 dip-slip (normal stress is applied as an
a) FIGURE released