17 Questions
What is a mitigation strategy for earthquake-induced ground subsidence?
Performing preparatory geotechnical investigations
How can infrastructure design mitigate earthquake-induced ground subsidence?
Constructing buildings with lateral force resistance
What role does land-use planning play in mitigating earthquake-induced ground subsidence?
Guiding development away from known hazard zones
How can scientists predict substantial ground subsidence in urban areas around Seattle and Portland?
By understanding mechanisms like aseismic deformation
Why is it crucial to understand mechanisms like soil liquefaction in earthquake-prone areas?
To minimize the impacts of earthquake-induced ground subsidence
What is the primary cause of earthquake-induced ground subsidence?
Soil structure and density
Which of the following soil characteristics makes it more susceptible to earthquake-induced ground subsidence?
High water saturation levels
How does tectonic activity contribute to earthquake-induced ground subsidence?
It releases stresses within the Earth's crust
What is the primary effect of earthquake-induced ground subsidence on land elevation?
It decreases the overall elevation of the land
Which of the following is a common consequence of earthquake-induced ground subsidence?
Formation of sinkholes or depressions
How does earthquake-induced ground subsidence differ from other types of land elevation changes?
It is a sudden and natural event
What effect can excessive groundwater extraction have on the risk of soil liquefaction during an earthquake?
It increases the risk of soil liquefaction.
How can engineering solutions help address earthquake-induced ground subsidence?
All of the above.
What is one of the environmental effects of earthquake-induced ground subsidence?
It can lead to changes in local hydrological conditions, affecting the availability of water resources and altering ecosystem functions.
Which of the following is a social impact of earthquake-induced ground subsidence?
Disruption of social structures and uncertainty among affected communities.
How can public education and awareness help address earthquake-induced ground subsidence?
All of the above.
What is the primary mechanism by which human activities can exacerbate the effects of earthquakes on ground subsidence?
Soil liquefaction, where the soil loses its structural integrity and behaves like liquid during an earthquake.
Study Notes
Earthquake-Induced Ground Subsidence
Earthquakes can cause significant changes in land surface elevations due to various mechanisms. These changes may lead to ground subsidence, which refers to a decrease in the level of the ground relative to its original position. There are several ways in which earthquakes can induce ground subsidence:
Mechanisms of Earthquake-Induced Ground Subsidence
Aseismic Deformation
Aseismic deformation is the movement caused by an earthquake that does not generate seismic waves detectable on the earth's surface. This type of deformation occurs during both the mainshock and aftershocks, and it can result in ground subsidence.
Soil Liquefaction
Liquefaction is a phenomenon in which the soil loses strength and stiffness following an earthquake, resulting in the soil behaving like a fluid. When this happens, the groundwater table rises and causes differential settlement and consequently, subsidence.
Surface Rupture
Surface ruptures occur when the shaking from an earthquake generates a crack along the earth's surface. This cracking can change the ground surface elevation and result in ground subsidence.
Examples of Earthquake-Induced Ground Subsidence
One notable example of earthquake-induced ground subsidence is the San Francisco Bay Area. Following the Loma Prieta earthquake of 1989, subsidence occurred throughout the region due to initial liquefaction and subsequent consolidation of soils. Another example is the Cascadia subduction zone offshore, where scientists predict repeated large earthquakes could trigger substantial ground subsidence within the urban areas around Seattle and Portland.
Mitigation Strategies
Mitigation strategies for earthquake-induced ground subsidence include:
Geotechnical Investigations
Preparatory geotechnical investigations can help identify potential hazards related to landslide and ground failure risk, making it possible to design structures with adequate seismic resistant capacity and assess the need for local and regional mitigation measures prior to construction.
Infrastructure Design
Structural designs should consider earthquake hazards. For instance, buildings should be designed to resist lateral forces without collapsing, preventing damage.
Land-Use Planning
Land-use planning can guide development away from known hazard zones, reducing future risks.
Conclusion
Earthquakes can contribute to ground subsidence through various mechanisms such as aseismic deformation, soil liquefaction, and surface rupture. Understanding these mechanisms is crucial in designing infrastructure and developing urban areas near seismically active regions to minimize the impacts of earthquake-induced ground subsidence.
Explore the different mechanisms through which earthquakes can induce ground subsidence, including aseismic deformation, soil liquefaction, and surface rupture. Learn about notable examples and mitigation strategies to reduce the impact of ground subsidence in seismic regions.
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