Question

Intermediate lavas can flow _____ than mafic lavas, due to the _______viscosity. a. slower, higher b. slower, lower c. faster, higher d. faster, lower

Short answer

Intermediate lavas flow slower than mafic lavas due to their higher viscosity; thus, the answer is a. slower, higher.

Step-by-step solution

Understanding Lava Types

Lava is generally classified into two main types: mafic and intermediate. Mafic lava, also known as basaltic lava, has a lower silica content and therefore tends to have a lower viscosity. Intermediate lava, such as andesitic lava, has a higher silica content, leading to a higher viscosity compared to mafic lava.

Viscosity and Flow Rate Relationship

Viscosity is a measure of a fluid's resistance to flow. A higher viscosity means the fluid is thicker and flows more slowly, whereas a lower viscosity means it is thinner and flows more easily. Therefore, the flow rate of the lava is inversely related to its viscosity.

Comparing Intermediate and Mafic Lavas

Based on the relationship between viscosity and flow rate, intermediate lavas, which have higher viscosity, will flow slower than mafic lavas that have lower viscosity. This is because the thicker, more resistant nature of intermediate lavas prevents them from flowing as quickly as mafic lavas.

Selecting the Correct Option

Review the options considering that intermediate lavas flow more slowly due to their higher viscosity. The correct choice is the one that matches this understanding. Option "a" (slower, higher) fits this description.

Key concepts

Lava Types

In the realm of geology, understanding the different types of lava is crucial. Generally, lava is categorized into various types based on its silica content. Two primary types that frequently come up in discussions are **mafic** and **intermediate** lavas. - **Mafic Lava**: This type, also known as basaltic lava, has a low silica content. As a result, it flows quite easily and quickly. - **Intermediate Lava**: This includes varieties like andesitic lava, which contain more silica than mafic lavas, leading to different geological behaviors. Knowing the type of lava helps in predicting its flow characteristics and potential impacts during volcanic events. Each type possesses distinctive properties that are pivotal in understanding volcanic activity.

Viscosity in Geology

Viscosity is a crucial concept when discussing geological phenomena such as lava flows. It refers to a fluid's resistance to deformation or flow. In simpler terms, it indicates how "thick" or "thin" a fluid is. - **High Viscosity**: This means the fluid is thick, like honey, and moves slowly. - **Low Viscosity**: Such fluids are thin, like water, and flow easily. In geology, viscosity determines how quickly volcanic lava travels across the landscape. Intermediate lavas, due to their higher viscosity, move slower compared to mafic lavas that have a lower viscosity. It's essential for geologists to assess the viscosity to understand and predict volcanic hazards effectively.

Flow Rate of Lava

The flow rate of lava is significantly influenced by its viscosity. Simply put, the flow rate describes how fast lava spreads on the earth's surface. - **High Viscosity Lava**: As seen with intermediate lavas, the flow is slower because these lavas are thicker. - **Low Viscosity Lava**: Mafic lavas have a quicker flow due to their thinner consistency. This relationship between viscosity and flow rate is essential for predicting lava path destinations and potential areas impacted by volcanic activity. Quick and effective prediction helps in planning and mitigation in regions prone to volcanic eruptions.

Mafic Lava

Mafic lava, commonly known as basaltic lava, is characterized by its low silica content. This specific attribute endows it with a lower viscosity, making it considerably less resistant to flow. - **Characteristics**: - Thinner consistency - Flows quickly over long distances Mafic lava's ability to cover expansive areas swiftly makes it a key type in understanding large-scale volcanic events. It tends to form broad shield volcanoes known for their extensive, gently sloping profiles. Knowing the properties of mafic lava is essential for studying volcanic land formations and anticipating the nature of eruptions.

Intermediate Lava

Intermediate lavas have a medium silica content, falling between mafic and felsic types. This results in a higher viscosity compared to mafic lavas, meaning they are thicker and flow more slowly. - **Characteristics**: - Higher resistance to flow due to increased viscosity - Tends to form steep-sided volcanoes, known as stratovolcanoes The slower flow of intermediate lava means it often cools and hardens before spreading too far, creating taller and steeper volcanic structures. Understanding intermediate lavas can help volcanologists predict how volcanic landscapes will evolve over time and assess the potential dangers posed by eruptions. These characteristics dictate not only the structure of the volcanoes formed but also the potential eruption style and hazard level associated with such lavas.