概括
基于扩张假设的模型解释了地震前的低地震波速度比率 (Vp/Vs). 垂直或随机定向的裂可以引起这些效应,甚至在蓝山湖也观察到.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 地震科学 地震科学 地震科学
背景情况:
- 在地震发生前的有限区域观察到异常低的地震波速度比率 (压缩波速度与剪波速度,Vp/Vs).
- 扩张性假设表明,岩石中裂的形成和传播可以改变地震波的速度.
研究的目的:
- 用扩张假设建模和解释地震前观察到的低Vp/Vs比率.
- 调查裂方向和密度在异常区域的地震波传播中的作用.
- 通过从纽约蓝山湖的预测观测来验证模型.
主要方法:
- 利用基于扩张假设的计算模型来模拟地震波传播.
- 在模型中包含不同的裂方向 (垂直,随机) 和密度.
- 将模型输出与苏联观测和蓝山湖的预测数据进行了比较.
主要成果:
- 模型成功地复制了地震前观察到的异常低的Vp/Vs比率.
- 发现垂直裂方向在产生观察到的效果方面是最有效的,尽管随机裂的密度较高产生了类似的结果.
- 这些模型还复制了来自纽约蓝山湖的预测观测.
- 证明了表面测量Vp/Vs受到与异常区边界特征相关的转移函数的影响.
结论:
- 扩张假设,加上裂机制,为地震前的Vp/Vs异常提供了可行的解释.
- 由于面向裂的地震异质性在前体地震观测中起着重要作用.
- 由于地下结构和速度梯度的影响,对Vp/Vs的表面测量需要仔细解释.
相关概念视频
Elastic Collisions: Case Study
Elastic collision of a system demands conservation of both momentum and kinetic energy. To solve problems involving one-dimensional elastic collisions between two objects, the equations for conservation of momentum and conservation of internal kinetic energy can be used. For the two objects, the sum of momentum before the collision equals the total momentum after the collision. An elastic collision conserves internal kinetic energy, and so the sum of kinetic energies before the collision equals...
Prediction Intervals
The interval estimate of any variable is known as the prediction interval. It helps decide if a point estimate is dependable.
However, the point estimate is most likely not the exact value of the population parameter, but close to it. After calculating point estimates, we construct interval estimates, called confidence intervals or prediction intervals. This prediction interval comprises a range of values unlike the point estimate and is a better predictor of the observed sample value, y.
The...
However, the point estimate is most likely not the exact value of the population parameter, but close to it. After calculating point estimates, we construct interval estimates, called confidence intervals or prediction intervals. This prediction interval comprises a range of values unlike the point estimate and is a better predictor of the observed sample value, y.
The...
Magnetostatic Boundary Conditions
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
Propagation of Uncertainty from Random Error
An experiment often consists of more than a single step. In this case, measurements at each step give rise to uncertainty. Because the measurements occur in successive steps, the uncertainty in one step necessarily contributes to that in the subsequent step. As we perform statistical analysis on these types of experiments, we must learn to account for the propagation of uncertainty from one step to the next. The propagation of uncertainty depends on the type of arithmetic operation performed on...
Elastic Strain Energy for Normal Stresses
Strain energy quantifies the energy stored within a material due to deformation under loading conditions, a fundamental concept in materials science and engineering. The strain energy can be modeled when a material is subjected to axial loading with uniformly distributed stress. In this scenario, the stress experienced by the material is the internal force divided by the cross-sectional area, and the strain induced is directly proportional to this stress through the modulus of elasticity.
If...
If...
Elastic Strain Energy for Shearing Stresses
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...


