Jack Gelinas                                                                                                       5/22/14

Current Event: San Andreas Fault                                                              Earth Science

          For my 4^th quarter current event I wanted to choose a topic relevant to what we were learning in class. I chose to do some research on the San Andreas Fault located on the West Coast of the United States by California.  The article I chose was “Groundwater Depletion Leading to more earthquakes along the San Andreas Fault” by Scott K. Johnson. In the article, he refers to the amount that the groundwater level has dropped as well as the amount that the ground surface has dropped. As tis water level goes down, scientists predict that sediments will compact and because of this the elevation decreases.  Because of these very radical occurences, earthquakes small and large have sprouted up along the San Andreas Fault which affects much of California. An interesting fact that I learned is that some of the small earthquakes that exist happen seasonally, peaking in the late summer and early fall. In this instance, earthquakes occur when the force of the two sides trying to move past each overcomes the friction keeping them from doing so, unclamping lowers the threshold for the slipping of an earthquake. The effects of these strange shifts in elevation have cause for a great amount of Groundwater to be lost in the San Joaquin Valley. “As the valley’s floor is sinking, the Earth’s crust is actually rising!” says Johnson. He later goes on to say that this sudden change was unpredictable and that a hundred years ago, this idea may have seemed unfathomable. This shows you how much unpredictability there is in our Earths crust.

          Overall, this idea of groundwater depletion in the San Andreas Fault has had an impact on the agricultural community the most. It makes water much harder to access from the ground which will affect wells and underground irrigation systems. It also reduces the amount of water in streams and lakes as well as the increasing the price in water pumping. The solid rock where the sediment may be found is considerably the most affected spot because of the compactions that have began to occur.

          To conclude, this article was HIGHLY interesting for me because it really helped me embrace plate tectonics and understand their impact on our society. Johnson did a great job of using outside sources to prove his points while also making it very understandable to someone who does not know too much about the topic. I would have liked to see Johnson provide a bit more analysis as to the effects that water depletion and earthquakes have on the San Andreas but I still believe he did a very solid job of getting his point across. In the end, I was very happy to be able to read this article and it helped me gain great knowledge on this topic!

         

Article Link: http://arstechnica.com/science/2014/05/groundwater-depletion-leading-to-more-earthquakes-along-san-andreas-fault/