Both occurred on Oppenheimer et al. Some 600 quakes struck San Ramon, also near the Calaveras Fault, in October 2015 (Xue et al, 2018). This article has been updated to reflect recent earthquakes in the swarm. Over 70 quakes have struck in the area around the Calaveras Dam since mid-August. Although the area has seen little significant seismic activity over the past 100 years, paleoseismic studies at Leyden Creek about one mile (2 kilometers) north of the dam indicate that this section of the northern Calaveras fault has generated a number of ground rupturing earthquakes of possibly up to around magnitude-7.0 over the last 2,500 years (Kelson et al. It produced the October 30, 2007 … The Bay Area fault system and the spot (red star) where the Hayward Fault branches off from the Calaveras Fault. The Calaveras fault system runs over 80 miles, from south of Hollister into the Danville-Walnut Creek area. Amer., 99, 1746–1759, doi: 10.1785/0120080305 The first quake was reported at 6:58 a.m. More than 35 quakes ranging as high as a magnitude-3.5 have been recorded by the U.S. Geological Survey since September 27. Monitoring Velocity Variations in the Crust Using Earthquake Doublets: An Application to the Calaveras Fault, California July 1984 Journal of Geophysical Research Atmospheres 89:5719-5731 The largest historical quake on the Calaveras Fault was a M=6.6 event in 1911 (Doser, 2009), but far too little is known about this large event. The reservoir sits atop a major branch of the San Andreas Fault system called the Calaveras Fault. Earthquake scientists are far more worried about the potential violence of a more northern stretch of the Calaveras Fault, between the towns of Danville and San Ramon. The reservoir is located less than 20 miles from where Tesla is based in Fremont, California, and sits on the Calaveras fault system. PUSH (Probabilistic Uniform Seismic Hazard), http://temblor.net/earthquake-insights/calaveras-535/, When preparing for earthquakes, don’t forget the small ones, American Geophysical Union meeting brings student research to light, Surface deformation observed in moderate Greek quake. That is enough to fill Levi’s Stadium from bottom to top four times, according to SFPUC. These shallow repeaters align well … Two minutes after 9 a.m., a third earthquake hit, registering a magnitude of 3.3 at a depth 4.3 km. Another swarm struck the central portion of the Calaveras Fault in April 2016 (http://temblor.net/earthquake-insights/calaveras-535/); neither triggered a larger shock. The Calaveras fault here is unusual because it creeps, moving a few millimeters per year, instead of storing up energy and releasing it all in a big earthquake. The largest earthquake within 30 miles of Calaveras County, CA was a 3.3 Magnitude in 2017. At that time, most U.S. seismic observatories were run by scientist priests at Jesuit universities. The SFPUC began refilling the Calaveras Reservoir last year, after dam construction was completed, and as of now it is at 62% capacity, according to the SFPUC. A series of small earthquakes near the recently built Calaveras Dam replacement is a reminder of the significant seismic hazard at the new dam site. When full, it can store 96,850 acre-feet, or 31 billion gallons of water. Soc. The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometers (750 mi) through California. That makes it a favorite laboratory for Earth Scientists and students to see faulting in slow-motion. The USGS database shows that there is a 19.41% chance of a major earthquake within 50km of Calaveras County, CA within the next 50 years. With a slip rate of about 15 mm/yr (0.6 in/yr) and a length of about 100 km (60 mi), the Calaveras is highly active and certainly capable of a M7+ earthquake. The Calaveras reservoir provides drinking water storage for residents throughout California, according to the San Francisco Public Utilities Commission (SFPUC), who manages the reservoir. Neither is construction of the dam itself, because excavated material was not removed from the site, but instead only shifted around over a small area, Burgmann said. Excavated areas were extensively mapped to maintain a precise record of the geologic features in the subsurface that could affect the new dam’s seismic resilience. The Calaveras fault produced the M6.2 Morgan Hill Earthquake in 1984. Within a minute, it was followed by a 3.6-magnitude quake along the Calaveras Fault in Santa Clara County. Construction on the new Calaveras Dam exposed faults not previously mapped. In 1979, the 5.7M Coyote Lake Earthquake ruptured to the south of the 1984 and 1911 earthquakes. He noted that there have been several large earthquakes linked to construction of dams and reservoirs in India and Egypt. It struck along the Calaveras Fault and had a depth of 7.4 kilometers, according to the USGS. The Calaveras Fault is a mostly right-lateral, strike-slip fault. The Calaveras and Hayward faults extend up the east side of the San Francisco Bay. Most likely, the earthquakes are simply releasing built-up stress due to the ongoing motion along the Calaveras Fault, Harlan says. future moderate earthquakes on the Calaveras Fault. The northern segment of the Calaveras Fault is virtually locked and this segment of the fault creeps at a rate between 2 and 3 mm/yr. But by the time these professors began to die in mid-century, their lifelong seismogram archives were—inconceivably and unconscionably—thrown out. Hayward-Calaveras fault zone (HCFZ), characterization of the creep rates along the faults with a high spatial resolution is necessary. Along some active faults, deformation and offset occur continuously even in the absence of large earthquakes; this is referred to as fault creep which generally proceeds at rates of millimeters to tens of millimeters per year. During the past week, 75 quakes have rattled the beautiful town of Danville, scene of the beloved Robin Williams movie, “Mrs. We suggest that Zone V fails only … The initial earthquake The similarity of seismograms recorded by two seismic stations demonstrate that the 31 October 2007 moment magnitude M5.4 Alum Rock earthquake is a repeat of a 1955 M L 5.5 earthquake. The U.S. Geological Survey (USGS) publishes updated frequency and severity likelihood every six years for the entire U.S. The Hayward Fault splinters from the Calaveras Fault, which itself is an offshoot of the A magnitude-1.9 tremor on October 8 was the latest in a series of small earthquakes near Northern California’s Calaveras Dam, located about 38 miles (61 kilometers) southeast of San Francisco. However, the rms residuals for P-wave arrivals at many of the network stations were as high as 0.25 sec due to the laterally heterogeneous structure of this area which deviates from the … The San Andreas fault system is the … Within a minute, it was followed by a magnitude 3.6 quake along the Calaveras Fault in Santa Clara County. SAN JOSE (KRON) — Two earthquakes shook the South Bay on Tuesday morning. Final Technical Report to US Geological Survey, National Earthquake Hazards Reduction Program. Engineers moved 12 million cubic yards of earth and rock to make room for and build the new dam. There are several reasons why these earthquakes may be occurring here. At the same time, the North American Plateis moving southwestward relative to the Earth's core, but southeastward relative to the Pacific Plate, due to the latter's much faste… “Swarms may indicate other activity in the area,” said Burgmann. Lian Xue, Roland Bürgmann , David R. Shelly, Christopher W. Johnson, Taka’aki Taira (2018), Kinematics of the 2015 San Ramon, California earthquake swarm: Implications for fault zone structure and driving mechanisms, in press, Earth and Planetary Science Letters. Calaveras County, CA has a moderate earthquake risk, with a total of 1 earthquakes since 1931. Credit: Rick Harlan (used with permission of SFPUC). The Hayward Fault runs from San Pablo Bay to Fremont. The north-northwest trending Calaveras Fault makes a westward bend or stepover under the northern end of the reservoir, crossing from the east bank of the reservoir south of the dam to the west side of Observation Hill which forms the left (west) abutment of the dam, according to a technical report on the Calaveras Fault. At that time, most U.S. seismic observatories were run by scientist priests at Jesuit universities. Credit: Dicklyon (CC BY-SA 4.0). Earthquake swarms usually end without a major event and generally die out within days to months. The quake was reported at 10:35 a.m. and was centered east of Alum Rock Park. “As I understand it, the excavated material [at Calaveras] was mostly put back into the nearby new dam embankment,” he said. Although most of the quakes in this week’s swarm are 3-5 km (2-3 mi) from the Calaveras Fault, the swarm has been migrating toward the Calaveras over the past few days. are the most studied and understood fault systems in the world. “I think the swarm is just a good reminder of seismic hazard that exists along the fault.”. The HCFZ considered here encompasses the HF, the northern CF, and the central CF from the junction with the northern CF to Gilroy (Figure 1). The fault cuts through the towns of Walnut Creek, San Ramon, Dublin, Pleasanton, Sunol, and Hollister. In Hollister the Calaveras Fault is displaying aseismic motion—one side of the fault is slipping past the other side of … Construction on a new earth-and-rock-fill dam began in 2011 and was completed in May 2019, according to the SFPUC. California Geological Survey Witter, R. C., Kelson, K. I., Barron, A. D., & Sundermann, S. T. (2003). 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