FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

1 GENERAL INFORMATION FIGURE 11 MAP OF RIVER
1 PREDICTIVE ANALYSIS OF INTERVAL CHOLECYSTECTOMY FIGURE 1
1 QUALITY ASSESSMENT FIGURE S1 RISK OF BIAS ASSESSMENT

11 SUPPLEMENTAL FIGURES SF1 SAMPLES CLUSTER BY STRAIN PLOT
12 •• WHICH OF THE POSITIONVERSUSTIME CURVES IN FIGURE
3 SUPPLEMENTARY FIGURES 画布 196 FIGURE S1 PHYLOGENETIC PROFILES

Locating an Earthquake


FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Figure 1


Background: The focus of an earthquake is the place inside the Earth where the energy is release as movement occurs on a fault. The deepest earthquakes that have been recorded occur at depths of 600 km. The epicenter is the point on the Earth’s surface directly above the focus. Seismologists plot the epicenter.

FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS






When an earthquake occurs, seismic waves immediately radiate away from the focus in all directions. P-waves are compressional waves, material expands and compresses in the direction of wave motion. P-waves are the fastest moving seismic waves. P-waves moving along the surface can cause the ground to buckle and fracture.


S

Figure 2

-waves oscillate materials in right angles to the direction of wave motion. S-waves are slower than P-waves. They travel in any plane and produce up-and-down and sideways motion of the ground.


Use the earthquake seismogram in figure 3 to answer the following questions:

FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Figure 3



  1. How long did the entire earthquake recording last? ___________________

  2. How much time elapsed between the P- and S-waves? ___________________

  3. How much time elapsed between the arrival of the P-wave and the first surface wave? ____________

  4. How does the maximum amplitude of the surface waves compare with the maximum amplitude of the P-waves? _________________________________________________________

  5. What was the approximate average period of the surface waves? ___________________

Figure 4


PFIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS - and S-waves leave the focus at the same instant in time. As they get further from the focus, P- and S-waves get further and further apart. The time difference between the P- and S-waves allows seismologists to determine how far away an earthquake occurred from a seismic station. The time-travel graph at right is used to determine distance to an earthquake epicenter.

  1. How do the arrival times of the first P-waves and S-waves change with distance from the epicenter?





  1. What is the difference in arrival times between the P- and S-waves for stations at the following distances from an epicenter:

    1. 1000 km

    2. 2000 km

    3. 3000 km


Using figures 3 and 4, answer the following questions:

  1. What is the distance from the epicenter to the seismic station? ___________________

  2. How long after the earthquake did the P-wave arrive at the station? _________________


  1. If the P-wave was recorded at 4:30 am local time, when did the earthquake occur? ___________________


EFIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Figure 5

xamine figure 5. Using seismograms from at least three different stations and the time travel graph, we can locate the epicenter of an earthquake. First we locate the stations on a map. Then we draw a circle around the station with a radius the same distance the station is from the epicenter. Repeat this for each of the three stations. The epicenter of the earthquake is the same as where the circles intersect.



When the seismogram stations are closer to the earthquake epicenter, we need to use a time-travel graph that is scaled appropriately. Use Figure 6 to determine the distances the stations are from the epicenter then draw circles centered on the stations with a radius of that distance to determine the location of the earthquake epicenter.

Figure 6


FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS











FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Seismic Station—Fresno, CA


FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Seismic Station—Phoenix, AZ


FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Seismic Station—Las Vegas, NV





Station

Tp

Ts

ΔT

Distance

Fresno, CA

0 Seconds




Phoenix, AZ

0 Seconds




Las Vegas, NV

0 Seconds





FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

 


FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Seismic station---Akita, Japan

FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Seismic station—Pusan, South Korea

 

FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS

Seismic station—Tokyo, Japan

Station

Tp

Ts

ΔT

Distance

Akita, Japan

0 Seconds




Pusan, S. Korea

0 Seconds




Tokyo, Japan

0 Seconds





FIGURE 1 BACKGROUND THE FOCUS OF AN EARTHQUAKE IS



4 CROSSWALK FRICTION TESTS (ATTACHMENT) FIGURE 1 AN INTERSECTION
7 BILDER OG UTKIPPSFIGURER I PRIMÆR 3 –
AIR CARGO FIGURES FOR THE MAIN UK FREIGHT AIRPORTS


Tags: figure, background, focus, earthquake