Why are earthquakes so common at the San Andreas Fault in California, but volcanic eruptions are highly unlikely?.
There are three main types of boundaries formed by tectonic plate movement. These boundaries named Convergent Plate, Divergent Plate and Transform Plate boundaries as you can see above. The San Andreas fault is an example to transform boundary fault and it cuts California right in half. It is perhaps the most famous and well known transform fault in the world, where the Pacific Plate meets the North American Plate and when they slip past each other, it causes large earthquakes in the city. As mentioned, this is an example to transform boundary faults and these type of plate boundaries are mostly found on the ocean floor, where they can frequently balance functional spreading ridges to shape a zigzag pattern between plates.There are quite a few on land and the San Andreas fault symbolizes one of those few uncovered transform fault on land.
What tectonic activity occurs at such plate margins?.
Transform plate margins are having two plates that is moving smoothly against each other horizontally. Thus, causing numerous earthquakes which is often quite damaging on land. As mentioned, The San Andreas fault is a famous transform fault in California, mostly because where it is located. The picture shows where the San Andreas fault is located. So on the northern eastern side of the picture, that is where North American plate is and below to the left of the picture is where Pacific plate is. So there is a transform boundary between the pacific plate and North American plate. As we can see in the picture, the San Andreas fault runs along where all those cities and towns are. It is in California and runs from San Diego to San Francisco where major earthquakes occurred along. They get earthquakes very often and these earthquakes are mostly measurable that has been recorded. They have had quite a few in the past that have been massive.