The distribution of geophysical hazarsd Flashcards
What is the primary distribution pattern of earthquakes and volcanoes worldwide?
Earthquakes show a clear linear distribution, occurring more frequently and widely than volcanoes. Earthquakes occur: Around the Pacific Ring of Fire – This region, forming a horseshoe shape around the Pacific Ocean, accounts for around 90% of the world’s earthquakes.
Where is the distribution of earthquakes closely linked?
To all plate boundaries and plate boundary zones.
What locations are associated with the distribution of volcanoes?
Divergent boundaries, convergent boundaries where subduction occurs, and hotspots.
What percentage of the world’s earthquakes occur at the Pacific Ring of Fire?
90%.
Where do the most powerful earthquakes occur?
In subduction zones.
What percentage of all volcanoes occur at subduction zones along the Pacific Ring of Fire?
75%.
What types of volcanoes are commonly found at hotspots and divergent plate boundaries?
Shield volcanoes.
How do shield volcanoes differ from composite volcanoes in terms of eruptions?
Shield volcanoes have high-frequency eruptions and lower explosivity.
What is the Volcanic Explosivity Index (VEI) used for?
Measuring the magnitude of volcanic eruptions.
What factors are considered in calculating the Volcanic Explosivity Index?
- Amount of volcanic material ejected
- Height of the material thrown into the atmosphere
- Duration of the eruptions.
True or False: High explosivity eruptions have low recurrence intervals.
True.
What is the relationship between earthquake magnitude and recurrence intervals?
High-magnitude earthquakes occur less frequently and have lower recurrence intervals.
What scale is used to measure earthquake magnitude?
The Moment Magnitude Scale.
What is the significance of the Benioff Zone in earthquake occurrence?
It is where high-magnitude earthquakes tend to occur during subduction.
How do geologists use recurrence intervals for risk assessment?
To create seismic hazard curves that estimate the probability of earthquakes of certain magnitudes.
What factors increase the risk of landslides?
- Steep mountainous regions
- Coarse soil
- High rainfall events
- Population pressure
- Deforestation
- Road construction
- Mining and plantations.
Fill in the blank: Landslide risk is greatest in _______ regions with high rainfall events.
[populated]
What regions are highlighted as having a high risk of landslides?
- Western regions of the Americas
- East Asia
- South East Asia.
What human processes exacerbate landslide risk in Nepal?
- Deforestation
- Road construction.
