Podcast
Questions and Answers
Inge Lehmann's analysis of seismic waves led to the discovery of what key property of Earth's inner core?
Inge Lehmann's analysis of seismic waves led to the discovery of what key property of Earth's inner core?
- It is solid, contrary to previous assumptions that it was liquid. (correct)
- It is in a state of constant convection, generating Earth's magnetic field.
- It is composed of lighter elements like silicon and oxygen, unlike the outer core.
- It is primarily composed of iron and nickel, similar to the outer core.
What phenomenon relating to seismic waves did scientists observe that initially led them to believe the Earth's core was liquid, and what observation contradicted this?
What phenomenon relating to seismic waves did scientists observe that initially led them to believe the Earth's core was liquid, and what observation contradicted this?
- The presence of shadow zones where few waves were detected; the occurrence of weak P-waves in the shadow zone. (correct)
- The detection of strong S-waves at the Earth's poles; the absence of P-waves near the equator.
- The consistent bending of P-waves towards the surface; the consistent arrival times of S-waves worldwide.
- The absence of S-waves in shadow zones; the presence of strong P-wave reflections in the same zones
How did Inge Lehmann explain the occurrence of weak P-waves in the shadow zone, challenging the existing model of Earth's core?
How did Inge Lehmann explain the occurrence of weak P-waves in the shadow zone, challenging the existing model of Earth's core?
- By proposing that the waves were diffracted around a solid inner core, causing them to weaken.
- By suggesting that the waves were deflected by the boundary between the inner and outer regions of the Earth's core. (correct)
- By hypothesizing that the waves were reflected by irregularities in the mantle-core boundary.
- By theorizing that the waves were converted into S-waves within the liquid outer core.
In what year did Inge Lehmann publish her groundbreaking 'P' paper that demonstrated the Earth must have an inner core?
In what year did Inge Lehmann publish her groundbreaking 'P' paper that demonstrated the Earth must have an inner core?
Besides discovering that the Earth's inner core is solid, what other significant discovery is attributed to Lehmann regarding the Earth's core?
Besides discovering that the Earth's inner core is solid, what other significant discovery is attributed to Lehmann regarding the Earth's core?
What type of seismic waves were analyzed by Inge Lehmann to determine the structure of the Earth's core?
What type of seismic waves were analyzed by Inge Lehmann to determine the structure of the Earth's core?
What initial observation regarding seismic waves led scientists to believe the Earth's core was liquid?
What initial observation regarding seismic waves led scientists to believe the Earth's core was liquid?
The analysis of data from a large earthquake in New Zealand in 1929 contributed to which of Inge Lehmann's milestones?
The analysis of data from a large earthquake in New Zealand in 1929 contributed to which of Inge Lehmann's milestones?
What prompted scientists to study earthquake shock waves?
What prompted scientists to study earthquake shock waves?
According to the depiction, what aspect of the Earth's inner core contributes to making the core of the Earth "more intriguing than was thought?"
According to the depiction, what aspect of the Earth's inner core contributes to making the core of the Earth "more intriguing than was thought?"
Flashcards
Seismic Shocks (Lehmann)
Seismic Shocks (Lehmann)
Analyzed data from a New Zealand earthquake in 1929.
Lehmann's 'P' Paper
Lehmann's 'P' Paper
Published a paper in 1936 demonstrating Earth has an inner core.
Lehmann's core boundary
Lehmann's core boundary
Discovered another core boundary 137 miles (220 km) below Earth's surface in 1959.
Earthquake shock waves
Earthquake shock waves
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Shadow zones
Shadow zones
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Lehmann's P wave deflection
Lehmann's P wave deflection
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Earth's inner core rotation
Earth's inner core rotation
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Lehmann's Discovery
Lehmann's Discovery
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Study Notes
- Inge Lehmann was a seismologist whose data analysis revealed the Earth's solid core
- Born in Copenhagen, Denmark, she earned a degree in mathematics before studying earthquakes
- Scientists knew that shock waves from earthquakes, P (primary) and S (secondary) waves, could travel through the Earth and be detected
- Shadow zones, where few waves were detected, were thought to occur because shock waves were deflected by the Earth's liquid core
- The occurrence of weak P waves in the shadow zone was not fully explained
- In 1936, Lehmann proposed that these P waves were deflected by the boundary between the inner and outer regions of the Earth's core
- She posited that the inner region was solid, contrary to previous assumptions
- Lehmann's "P" paper was published in 1936, demonstrating that the Earth must have an inner core
- In 1959, she discovered a core boundary 137 miles (220 km) below the Earth's surface
- The core of the Earth is more complex than previously thought because the inner core rotates separately
- She analyzed data from a large earthquake in New Zealand in 1929, interpreting the P waves
- Bertha Swirles described Lehmann as "The master of a black art" in 1994
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