Question

2 multiple choice 20 points
how does the s-p interval method provide valuable information for calculating the distance to the epicenter of an earthquake, and what specific characteristics of seismic waves does it rely on?

the s-p interval measures the time between the arrival of the primary (p) and secondary (s) seismic waves, with a longer s-p interval indicating a closer earthquake epicenter.

the s-p interval relies on the number of aftershocks following the main earthquake event and does not provide information about distance.

the s-p interval is irrelevant for determining earthquake distance; instead, it is used to estimate the earthquakes magnitude.

the s-p interval is based on the difference in speed between p and s waves, with a shorter interval suggesting a closer epicenter.

3 multiple choice 20 points
which is an accurate comparison of the focus and epicenter of an earthquake?

the focus is the location farthest from the earthquake and the epicenter is closest to the earthquake.

the epicenter is the site on earths surface directly above the focus.

the epicenter is the location farthest from the earthquake and the focus is the closest to the earthquake.

the focus is the site on earths surface directly above the epicenter.

Explanation:

Analyze S-P interval characteristics

The S-P interval represents the difference in arrival times between the faster primary (P) waves and the slower secondary (S) waves. Because P-waves travel faster than S-waves, the time gap between their arrivals increases with distance from the epicenter. Therefore, a shorter S-P interval indicates that the recording station is closer to the epicenter, while a longer interval indicates it is farther away.

Compare focus and epicenter

The focus (or hypocenter) is the exact point within the Earth's crust where the earthquake rupture begins and seismic energy is released. The epicenter is the point on the Earth's surface directly vertically above the focus.

Answer:

Question 2

• (A) The S-P interval measures the time between the arrival of the primary (P) and secondary (S) seismic waves, with a longer S-P interval indicating a closer earthquake epicenter.
• (B) The S-P interval relies on the number of aftershocks following the main earthquake event and does not provide information about distance.
• (C) The S-P interval is irrelevant for determining earthquake distance; instead, it is used to estimate the earthquake's magnitude.
• (D) The S-P interval is based on the difference in speed between P and S waves, with a shorter interval suggesting a closer epicenter. (Correct answer)

Question 3

• (A) The focus is the location farthest from the earthquake and the epicenter is closest to the earthquake.
• (B) The epicenter is the site on Earth's surface directly above the focus. (Correct answer)
• (C) The epicenter is the location farthest from the earthquake and the focus is the closest to the earthquake.
• (D) The focus is the site on Earth's surface directly above the epicenter.