is shallow focus mostly found at destructive plate boundary associated with the collision of two oceanic crust

Yes, shallow focus earthquakes are commonly found at destructive plate boundaries, also known as convergent boundaries. However, they are not exclusively associated with the collision of two oceanic crusts. They can also occur where an oceanic crust collides with a continental crust.

Here's a step-by-step explanation:

1. Plate Tectonics: The Earth's crust is divided into several large and small pieces known as tectonic plates. These plates are constantly moving, albeit very slowly.

2. Destructive Plate Boundaries: These are areas where two tectonic plates are moving towards each other. This can involve two oceanic crusts, two continental crusts, or an oceanic and a continental crust.

3. Subduction: When an oceanic crust collides with another oceanic crust or a continental crust, it is usually forced downwards into the mantle in a process known as subduction. This is because the oceanic crust is denser than the continental crust.

4. Earthquakes: The process of subduction causes intense pressure and heat. When the stress on the rock becomes too great, it is released in the form of an earthquake. If this earthquake originates at a depth of less than 70 km, it is known as a shallow focus earthquake.

5. Location: While shallow focus earthquakes can occur at all types of plate boundaries, they are most common at destructive (or convergent) boundaries due to the process of subduction.