The magnitude 6.0 earthquake occurred early in the morning on August 24, 2014, on the West Napa Fault. State Sen… Seismicity in the Napa area 1973-2015, all magnitudes. The epicenter was located approximately 9 km south of the city of Napa in northern California. The August 24, 2014, South Napa earthquake (M6.0) produced significant damage resulting from shaking, fault rupture, fault afterslip, and ground deformation. Fault traces and other lineaments show levels of afterslip hazard. A shaking intensity of VII-VIII is described as strong to severe, and very likely woke up all but the most heavy of sleepers. All of the faults and/or imagery lineaments shown as heavy green lines on this map may be considered to have a low level of afterslip hazard. There is no denying that. Twitter. A smaller magnitude 5.0 earthquake on the same fault had damaged the city of Napa in 2000. The 6.0-magnitude quake struck at 3:20 … They walked across the landscape to trace where the fault had ruptured the Earth’s surface, and mapped the earthquake surface rupture and post-earthquake afterslip, in great detail using mobile laser scanning (a truck-mounted Lidar system), alignment arrays (such as creepmeters that directly measure extremely small fault movements), GPS measurements, and satellite-based radar surveys (InSAR and UAVSAR). The shaking caused some damage to wood-frame houses and significant damage to some commercial buildings in downtown Napa, including the 1870 courthouse. To determine the continuity and extent of the faults that ruptured during the South Napa earthquake and its aftershocks, and to search for possible interconnections with other mapped faults, USGS recorded aftershocks using temporary seismograph arrays that were positioned across the rupture zone and mapped faults located north and south of the rupture. Assuming a continuous fault zone, the West Napa – Franklin Fault zone could be capable of generating a much larger magnitude earthquake than the M 6.0 that occurred on August 24, 2014. the wood-frame houses that were damaged were older ones that had not been retrofit (see links below for retrofitting information). These recordings are being used, in part, to better understand the performance of residences and older masonry buildings that have been retrofitted. the commercial buildings were pre-1950 masonry and had not been built to current code standards or retrofit. The seismic hazard posed by the West Napa Fault System is still being evaluated. Initially, the fault afterslip was rapid and extended into at least the southern part of the Browns Valley neighborhood in the city of Napa. Ground shaking was significant with accompanying maximum Modified Mercalli Intensities between VIII and IX. Caption: A map shows the location of the August 24, 2014 earthquake just south of Napa, California. The California Integrated Seismic Network detected the South Napa earthquake immediately, and the first ShakeMap, issued four minutes after the earthquake, depicted the violent shaking in the immediate area. “Did You Feel It?” community intensity map indicating the severity of shaking felt by people in central California during the South Napa Earthquake in 2014. Numerous vehicles were trapped by fallen carports at the Charter Oaks apartments on Browns Valley Road in Napa, Calif., following the South Napa earthquake Sunday morning, Aug. 24, 2014. USGS issued a forecast for the continuing afterslip for some homes that was included in the report for FEMA. August 25, 2014 at 8:22 PM The earthquake was unusual for the length of surface rupture (8 miles), the amount of surface slip (up to 18 inches), and the large afterslip that followed the earthquake (up to 14 inches). Within 1 hour after the earthquake, over 25,000 citizen scientists entered their data on the website, creating a map of the distribution of shaking that they felt. Scientists found that some of the fault segments that ruptured on the morning of August 24 had been previously mapped as part of the West Napa fault system, but the rupture also extended northward where no faults had been mapped before. (DYFI) webpage bookmarked, so as soon as the shaking stopped, they started reporting their experience of the shaking on DYFI. When the pressure adjusts and equilibrates with the water table, the flow will often return. There was no evidence for the shaking being strongly amplified in any particular pockets of the downtown area. Much of the fault appears to be smoothly slipping (afterslip) with no stuck spots that would usually fail in aftershocks. ), Napa Valley area red- and yellow-tagged structures shown as red and yellow squares. Symbol size represents earthquake magnitude, and fill color represents depth. These activities resulted in a comprehensive understanding of fault motion and ground response, in ways that could not have been imagined the last time (1989) there was a large quake in the San Francisco Bay Area. The South Napa Earthquake provided a valuable reminder to engineers and the public of what they should expect from time to time when they live in earthquake country. This earthquake was unusual for its size, because it had a relatively long surface rupture of 12.5 km (8 mi) with a significant amount of surface slip (up to 46 cm; or 18 in). Click on a pin on the map to see more information. Nicholas George looks under a buckled highway just outside Napa. 1: In the event of a natural disaster such as an earthquake, City Inspectors will perform an Facebook. M 6.0 - South Napa LOS ANGELES _ In a land where the mildest rumble elicits an anxious question _ "Did you feel that?" In addition, a M3.0 earthquake occurred on August 5, 2014, 19 days before the M6.0, which, in retrospect, some scientists/seismologists might consider a foreshock. Overview. An additional 14+ cm (5.5+ in) of slip was measured during the first 24 hours, and up to 20 cm (8 in) after 48 hours, mainly on southern half of the main fault strand. Warmer colors represent stronger shaking. Office of Communications and Publishing12201 Sunrise Valley DriveReston, VA 20192United StatesPhone: 703-648-4460. USGS Home Contact USGS Search USGS. And I am listening to KTVU TV News right now, … Where I was in San Francisco wasn’t close enough to the epicenter to do much other than wake people up. At least 87 people were injured early Sunday morning after the largest earthquake to hit California’s Napa Valley in 25 years struck near the Bay Area. After the 2014 South Napa Earthquake, approximately half the households in the city of Napa and in western Vallejo that reported an injury stated that the injury occurred during cleanup activities. Sometimes a single fault segment will slip and cause an earthquake, and other times many fault segments slip in unison, causing a larger earthquake. Damaged unreinforced masonry building on Main St. in downtown Napa. For further details, see Groundwater Effects from Earthquakes. The sharp rise starting on August 24 reflects an increased streamflow due to the South Napa Earthquake. Hydrograph showing stream flow in cubic feet per second on USGS streamgage on Sonoma Creek near Agua Caliente, from about August 23 - September 13, 2014. The first offset measurement was taken the day of the earthquake - about 6 cm (2 in) of right-lateral offset. Olivia Allen-Price. The 2000 M4.9 earthquake near Yountville is shown as a white star, and the South Napa earthquake is shown as a yellow star. For example, the California Department of Transportation (Caltrans) received an automated report that they could use to determine which bridges and overpasses experienced the greatest level of shaking and were most at risk to damage so they could prioritize inspections. Damage to structures decreased with distance from the rupture. the sedimentary basin - soft sediments amplify the shaking. USGS Geologists inspecting fault trace in a trench dug across one of the ruptures from the 2014 South Napa earthquake. The "Did You Feel It?" The earthquake woke people throughout northern California, in cities as far away as Sacramento and Santa Cruz. A few homes even shifted off of their foundations, which can be due to the failure of the cripple walls, which drop the floor to the foundation and sometimes allow houses to slide off the foundation. Some fault strands that broke in residential areas and damaged homes, had not previously been mapped. This event was of great interest to seismologists, especially at the Berkeley Seismolgical Laboratory. California Governor Jerry Brown called it the "South Napa Earthquake" in his official emergency declaration, widely reported in the press. After the earthquake, PEER summarized various preliminary observations, in which the following ground motion One year ago, the largest earthquake in over 25 years hit the San Francisco Bay Area, causing significant damage in California’s famous Napa Valley. This lack of ground failure was attributed to the lack of rainfall in the area; a shallower water table would have made the surface material less stable and more prone to ground failure. Residential structures and wineries surrounding this area were significantly damaged. An Instrumental Intensity “ShakeMap,” depicts the ground shaking produced by the 2014 South Napa earthquake. The red star is the location of the mainshock. A strong, 6.0-magnitude earthquake jolted Northern California yesterday (Aug. 24) at 3:20 a.m. local time. (Public domain. _ having even a few seconds of warning before an earthquake The M6.0 South Napa earthquake occurred on August 24, 2014. The moderate earthquake that struck California’s Napa Valley on Sunday collapsed older buildings, sparked fires and caused scores of injuries. On August 24, 2014, a magnitude-6.0 earthquake occurred in Napa, California. With one fatality, and approximately a half billion dollars of economic damage, the city of Napa is still recovering from last year’s quake. In the days, weeks and months that followed, scientists collected and analyzed data from instruments that recorded the event. Engineers and scientists determined that the worst-damaged buildings resulted from a combination of: The South Napa earthquake caused this ground surface rupture running through a viineyard near Buhman Road, Napa Valley, California. The relative motion on this fault is not well known but thought to be about 1 mm/yr (0.04 in/yr). Existing fault maps show that the Franklin Fault extends southward to the Calaveras Fault zone and the West Napa Fault extends north of the seismic array. The three largest were a M3.9 on August 26, a M3.2 a week after the mainshock on August 31, and then a M4.1 10 months later on May 22, 2015. ShakeCast is an application for automating ShakeMap delivery to critical users and for facilitating notification of shaking levels at user-selected facilities. Afterslip rates decreased dramatically in the months following the earthquake and is still being monitored by the USGS. In the month after the mainshock, there were 80 aftershocks of magnitude greater than or equal to 1.8. Email. The earthquake fault rupture extended northward from the epicenter, directing much of the seismic energy toward the city of Napa. The Did You Feel It? The sharp rise starting on August 24 reflects an increased streamflow due to the South Napa Earthquake. ), Locations of the traces of tectonic surface faulting produced by the South Napa earthquake overlain on an aerial photograph. The same could be said for the tornados in the midwest and south, and hurricanes in the southeast coastal areas. Geographic Names Information System (GNIS), Mapping, Remote Sensing, and Geospatial Data. Our better scientific understanding of the 2014 earthquake sheds light on the nature of earthquake faults and hazards in the region, and will enable communities to be better prepared and better able to withstand the next earthquake. 2014 South Napa Earthquake Retrospective. Lidar data were collected to aid specialized work on the South Napa earthquake including: (1) fault afterslip, especially in the Browns Valley residential neighborhood; (2) shaking and correlation to damage such as red- and yellow-tagged … The only other noteworthy earthquake in the Napa area in the recent past (since 1973) was the M4.9 Yountville earthquake on September 3, 2000. Also shown are locations of the mainshock (red dot), aftershocks (other dots), surface ruptures (red lines), locations of permanent (unfilled triangles) and temporary (filled triangles) seismic stations. map with 41,356 responses as of this writing. One year ago, the largest earthquake in over 25 years hit the San Francisco Bay Area, causing significant damage in California’s famous Napa Valley. It may extend further north or south and may connect with other fault zones. The South Napa earthquake occurred on Sunday, 24 August 2014 at 3.20 am local time at a depth of 10.7 km, having MW 6.0 and causing significant damage to unreinforced masonry (URM) buildings But this was no small earthquake, and as the small representative sample of Jawbone© data shows, many residents had trouble going back to sleep after this one. Copy Link. The following summary is what USGS (and USGS-funded) scientists have learned from the data one year after the earthquake. Show more about Online Teaching suggestions Webinar about teaching this module: Addressing Earthquake Hazards with LiDAR, GPS, and InSAR in Upper-level Undergraduate Courses The South Napa Earthquake caused extensive damage through both ground shaking and surface cracking (rupture). (Public domain. The highest intensities were MMI VII-VIII in the city of Napa and extending a littler farther north. Frequently Asked Questions (FAQs) for Tenants After the 2014 South Napa Earthquake To aid tenants who have been affected by the 2014 South Napa Earthquake. Afterslip forecast hazard map of the Browns Valley neighborhood and surrounding area in Napa, Calif. At 6.0 on the moment magnitude scale and with a maximum Mercalli intensity of VIII ( Severe ), the event was the largest in the San Francisco … First, to put the South Napa earthquake in context, the West Napa fault, which was the causative fault, is part of the large San Andreas Fault Zone (SAFZ) system. A. It caused much damage and injured many. ShakeMaps provide near-real-time maps of ground motion and shaking intensity following significant earthquakes. The SAFZ is not a simple, single fault, but rather a complex collection of smaller fault segments that collectively accommodate the horizontal movement between the North American Plate and the Pacific Plate. After the earthquake, one or more types of traumatic exposure were reported among 27% and 4% of Napa and western Vallejo households, respectively; Also, fault strands that had been mapped prior to this earthquake were not thought to be highly hazardous. Hydrograph showing stream flow in cubic feet per second on USGS streamgage on Sonoma Creek near Agua Caliente, from about August 23 – September 13, 2014. Residents in this area feel small earthquakes often, and they generally pause for a moment and then go back to whatever they were doing. This kind of hydrogeologic response to earthquakes is well known to scientists. These maps are used by federal, state, and local organizations, both public and private, for post-earthquake response and recovery, public and scientific information, as well as for preparedness exercises and disaster planning. The epicenter of that earthquake was 20 km (12 mi) NNW of the South Napa epicenter, and also on the West Napa fault system. (Josh Edelson/AFP/Getty Images) Kids skateboard over buckled roads in a residential neighborhood of Napa. The city of Napa was very strongly shaken: many historical masonry buildings and older residences were damaged. Inspection of the buildings after the earthquake yielded 100+ red-tagged structures, meaning immediate rehabitation is too dangerous. Rivers and streams in the area were flowing at record lows at the time of the quake because of the continuing drought, so when water began to flow again in some previously dry surrounding creeks and streams in the aftermath of the South Napa Earthquake, it prompted many nearby residents to scratch their heads. The California Geological Survey (CGS) is currently remapping the West Napa Fault System in concert with fault excavation (trenching) studies carried out by the USGS and CGS to evaluate the prehistoric record of rupture on the various fault strands. (Public domain.). The ground shaking was very strong along the fault and in the Napa Valley. Once fully implemented in the western U.S., the advance warnings of a few seconds up to a minute or more provided by the ShakeAlert system can be enough to slow public transit systems, open fire-house doors, and allow people to “Drop, Cover and Hold On.” Although there were no trains running at 3:20 a.m. when the earthquake happened, the Bay Area Rapid Transit (BART) system’s automated train-stopping system did successfully activate when the warning was received. The Earthquake Event Page application supports most recent browsers, view supported browsers. Almost three years have passed since the 2014 magnitude-6.0 South Napa earthquake. Or, try our Real-time Notifications, Feeds, and Web Services . The crosses and letters indicated cross-sections not shown in this image. Cullen 328 Let's discuss it 05:47, 26 August 2014 (UTC) This article in the San Jose Mercury News, published about 80 miles away, specifically mentions that "South Napa Earthquake" is emerging as the accepted name. (Public domain.). South Napa Earthquake Photos. Ultimately 41,000+ citizens shared their experiences, with the farthest felt report 300 km (186 mi) to the east in Reno, NV. 1: What does it mean if my apartment building was red, yellow, or green tagged*? Later investigations confirmed the shaking recorded on seismic instruments was consistent with the observed damage in the downtown area of Napa. USGS geologists and geophysicists, along with their colleagues from federal, state, and local government agencies and academia, started conducting field work immediately after the earthquake. Recent advances in technology let to more rapid assessment of the nature and effects of this quake, showcasing significant advances since the previous big quake in the San Francisco Bay area in 1989 – the magnitude 6.9 Loma Prieta earthquake. Ongoing fault movement along the surface rupture, called afterslip, continued for several months, and caused further damage to foundations and structures. A case study from the 2014 South Napa earthquake helps students make connections between interseismic strain and earthquake displacements. Many California residents have the Did You Feel It? (Public domain.). In addition, a M3.0 earthquake occurred on August 5, 2014, 19 days before the M6.0, which, in retrospect, some scientists/seismologists might consider a foreshock. For example, the surprising amount of afterslip observed gave scientists a new way to look at and forecast continuing hazards in the weeks to months, after the earthquake occurred. The timing of the earthquake was not only near the end of California’s normally dry season, but also during a multi-year-long severe drought. The number of aftershocks was less than usual for an earthquake of this size, 80 during the first month following the mainshock, compared to 320 following the M6.0 in Parkfield in 2006. No other surface features were found, such as evidence of liquefaction or landslides. In the wee hours of Sunday morning at 3:20am, the residents and wineries of Napa Valley were shaken by a magnitude 6.0 earthquake, the largest in the San Francisco Bay Area in over 25 years, and the first since the M7.9 1906 earthquake to rupture on the surface. No data point selected. The 2014 South Napa earthquake was the first large earthquake (Mag 6) to occur within the Plate Boundary Observatory GPS network since installation. 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