The seismogram is
“read” like a book, from left to right and top to bottom
(this is the direction that time increases). As with a book, the right end of any horizontal line “connects” with the left end of the line below it. Each line represents 15 minutes of data; four lines per hour.
How do you read a seismograph and epicenter?
A
circle
is drawn from each of the three different seismograph locations, where the radius of each circle is equal to the distance from that station to the epicenter. The spot where those three circles intersect is the epicenter (Figure 13.12).
How do you find P and S waves?
In P or compressional waves, the vibration of the rock is in the direction of propagation. P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves,
rock oscillates perpendicular to the direction of wave propagation
.
How do you use a seismograph?
A seismograph is
securely mounted onto the surface of the earth
so that when the earth shakes, the entire unit shakes with it EXCEPT for the mass on the spring, which has inertia and remains in the same place.
How are P and S waves shown on a seismogram?
The
primary, or P, waves travel most quickly
and are the first to be registered by the seismograph
What is the formula of P wave?
, density (reflection) coefficient;
R p = ρ 2 V p 2 − ρ 1
V p 1 ρ 2 V p 2 + ρ 1 V p 1 ≈ 1 2 ( Δ V p V p + Δ ρ ρ ) , P-wave normal-incidence reflection coefficient; R s = ρ 2 V s 2 − ρ 1 V s 1 ρ 2 V s 2 + ρ 1 V s 1 ≈ 1 2 ( Δ V s V s + Δ ρ ρ ) , S-wave normal-incidence reflection coefficient.
How fast do P waves travel?
In the Earth, P waves travel at speeds from
about 6 km (3.7 miles) per second in surface rock
to about 10.4 km (6.5 miles) per second near the Earth’s core some 2,900 km (1,800 miles) below the surface. As the waves enter the core, the velocity drops to about 8 km (5 miles) per second.
How does a seismometer work simple?
An instrument sensitive to tiny movements in the ground. A seismometer is a device that is sensitive to vibrations. It works on
the principle of a pendulum
: a heavy, inert mass with a certain resistance to movement (i.e. inertia) due to its weight is suspended from a frame by a spring that allows movement.
What is the difference between a seismograph and a seismogram?
The terms seismograph and seismometer are often used interchangeably; however, whereas both devices may detect and
measure seismic waves
, only a seismograph possesses the capacity to record the phenomena. A record produced by a seismograph on a display screen or paper printout is called a seismogram.
What does a Richter scale?
The Richter scale and how it measures
earthquake magnitude
. The Richter scale calculates an earthquake’s magnitude (size) from the amplitude of the earthquake’s largest seismic wave recorded by a seismograph
What is the relationship between S and P waves?
P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves,
rock oscillates perpendicular to the direction of wave propagation
. In rock, S waves generally travel about 60% the speed of P waves, and the S wave always arrives after the P wave.
What is the difference between P and S wave?
In P or compressional waves, the vibration of the rock is in the direction of propagation. P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves,
rock oscillates perpendicular to the direction of wave
propagation.
What is the set of P waves?
A P wave, or compressional wave
Where do P waves travel the fastest?
Because the
earth’s mantle
becomes more rigid and compressible as the depth below the asthenosphere
What is true P wave?
A P wave (primary wave or pressure wave) is one of the two main types of
elastic body
waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any affected location or at a seismograph.
