An unusual series of earthquakes recently struck San Ramon east of San Francisco in California. The largest earthquakes were magnitudes 4.2 and 3.8, and occurred as part of 76 earthquakes that struck on a single day. While it might appear that these all struck on the major Calaveras Fault, these may have a different origin. Thumbnail Photo Credit: Google Earth, Image © 2026 Vexcel Imaging US. Inc. This image was overlaid with text and then overlaid with GeologyHub made graphics (the image border & the GeologyHub logo). If you would like to support this channel, consider using one of the following links: (Patreon: http://patreon.com/geologyhub) (YouTube membership: https://www.youtube.com/channel/UCYeGh5VML5XPr5jYnzh3J6g/join) (Gemstone & Mineral Etsy store: http://prospectingarizona.etsy.com) (GeologyHub Merch Etsy store: http://geologyhub.etsy.com) Google Earth imagery used in this video: ©Google & Data Providers This video is protected under "fair use". If you see an image and/or video which is your own in this video, and/or think my discussion of a scientific paper (and/or discussion/mentioning of the data/information within a scientific paper) does not fall under the fair use doctrine, and wish for it to be censored or removed, contact me by email at [email protected] and I will make the necessary changes. Various licenses used in sections of this video (not the entire video, this video as a whole does not completely fall under one of these licenses) and/or in this video's thumbnail image (and this list does not include every license used in this video and/or thumbnail image): Public Domain: https://creativecommons.org/publicdomain/mark/1.0/ Sources/Citations: [1] U.S. Geological Survey 0:00 San Ramon Earthquakes 0:50 Major Fault Lines 1:43 Nearby Fault Lines 2:26 Aftershock Rates 3:14 Rainfall Trigger? 3:48 Aftershock Probabilities