America’s most famous fault line, the San Andreas, is known for its frequent earthquakes, but one part of the system, the San Jacinto Fault zone, in inland Southern California, has been surprisingly quiet for the last 200 years. Now new research has detected small tremors deep under the fault system, suggesting it’s not as calm as we once thought and may be ready to release a massive earthquake sometime soon. The San Jacinto Fault zone in Southern California is not actually a plate boundary but

rather serves as the stress release point between the North American Plate and the Pacific Plate as they grind together at the San Andreas Fault. An area of the San Jacinto Fault zone, known as the Anza Gap, is the main focus of the recent study.The researchers used a new highly sensitive detection method called multibeam back projection, which calculates plate movement while minimizing incoherent outside noise, to take measurements deep beneath the fault zone in inland Southern California.  FULL REPORT