Gelatin is a commonly used material for analog experiments in geophysics, investigating fluid-filled fracture propagation (e.g., magmatic dikes), as well as fault slip. Quantification of its physical properties, such as the Young’s modulus, is important for scaling experimental results to nature. Traditional methods to do so are either time consuming or destructive and cannot be performed in situ. We present an optical measurement technique, using shear waves. Polarizing filters enable visualization of the deviatoric stresses in a block of gelatin, so shear wave propagation can be observed. We demonstrate how the wave velocity can be measured and related to the Young’s modulus, show how the results are comparable to another methodology and discuss processing techniques that maximize the measurement precision. This methodology is useful for experimentalist, as it is simple to implement into a laboratory setting, can make precise, time-efficient estimates of the material strength and additionally is non-destructive and can be performed in situ.

明胶是用于地球物理模拟实验，研究充满流体的裂缝传播（例如岩浆岩）以及断层滑动的常用材料。量化其物理性质（例如杨氏模量）对于将实验结果缩放到自然状态非常重要。这样做的传统方法既费时又具有破坏性，无法执行原位。我们提出一种使用剪切波的光学测量技术。偏振滤光片可显示明胶块中的偏应力，因此可以观察到剪切波传播。我们演示了如何测量波速并与杨氏模量相关联，展示了结果如何与另一种方法可比，并讨论了使测量精度最大化的处理技术。这种方法对于实验师很有用，因为它很容易在实验室环境中实施，可以对材料强度进行精确，省时的估算，并且是无损的，可以执行原位。