The South Napa earthquake was very well recorded and produced a number of strong ground motion recordings that are of considerable interest to the engineering community. Earthquake Science Center, Menlo Park, California. Sometimes a single fault segment will slip and cause an earthquake, and other times many fault segments slip in unison, causing a larger earthquake. Older structures tended to experience more damage than more recently built structures Earthquake retrofitting of older structures can help to minimize damage in future earthquakes. 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. 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. (Public domain.). Or, try our Real-time Notifications, Feeds, and Web Services . The numbers of aftershocks following the earthquake was relatively low for an earthquake of this size, and in contrast to other large Californian earthquakes, the aftershock locations do not clearly outline the main fault rupture surface. 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. The ground shaking was very strong along the fault and in the Napa Valley. Nicholas George looks under a buckled highway just outside Napa. August 25, 2014 at 8:22 PM The "Did You Feel It?" The first offset measurement was taken the day of the earthquake - about 6 cm (2 in) of right-lateral offset. 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 first PAGER Assessment (providing fatality and economic loss impact estimates) was issued 13 minutes after the earthquake, and accurately forecast a low level of human casualties, but significant economic losses in the area. Afterslip rates decreased dramatically in the months following the earthquake and is still being monitored by the USGS. The following summary is what USGS (and USGS-funded) scientists have learned from the data one year after the earthquake. Results suggest the West Napa Fault and the Franklin Fault (to the southeast) may be continuous at depth. the commercial buildings were pre-1950 masonry and had not been built to current code standards or retrofit. An Instrumental Intensity “ShakeMap,” depicts the ground shaking produced by the 2014 South Napa earthquake. After the earthquake, one or more types of traumatic exposure were reported among 27% and 4% of Napa and western Vallejo households, respectively; The 6.0-magnitude quake struck at 3:20 … Shallow slipping across the fault, known as afterslip, continued after the mainshock and lasted for several months. Both the Napa and Peru earthquakes struck within about one day of this prediction. Also, fault strands that had been mapped prior to this earthquake were not thought to be highly hazardous. 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. A. Aug 25, 2014. The West Napa fault extends along the western margin of the basin that underlies much of Napa Valley. The team comprised a diverse mix of perspectives and backgrounds, including The sharp rise starting on August 24 reflects an increased streamflow due to the South Napa Earthquake. (Public domain. Caption: A map shows the location of the August 24, 2014 earthquake just south of Napa, California. The first ShakeCast was issued 11 minutes after the earthquake. Seismicity in the Napa area 1973-2015, all magnitudes. 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. The magnitude 6.0 earthquake occurred early in the morning on August 24, 2014, on the West Napa Fault. In the days, weeks and months that followed, scientists collected and analyzed data from instruments that recorded the event. _ having even a few seconds of warning before an earthquake Click on a pin on the map to see more information. 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. Hurricane Marie peaked on 8/24 at 21 UTC - about 2 hours from the Peru earthquake. The relative motion on this fault is not well known but thought to be about 1 mm/yr (0.04 in/yr). The 2000 M4.9 earthquake near Yountville is shown as a white star, and the South Napa earthquake is shown as a yellow star. ShakeMaps provide near-real-time maps of ground motion and shaking intensity following significant earthquakes. M 6.0 - South Napa The epicenter of that earthquake was 20 km (12 mi) NNW of the South Napa epicenter, and also on the West Napa fault system. California Governor Jerry Brown called it the "South Napa Earthquake" in his official emergency declaration, widely reported in the press. Almost three years have passed since the 2014 magnitude-6.0 South Napa earthquake. No data point selected. Key Recovery Factors for the August 24, 2014, South Napa Earthquake. Warmer colors represent stronger shaking. There is no denying that. The city of Napa was very strongly shaken: many historical masonry buildings and older residences were damaged. Later investigations confirmed the shaking recorded on seismic instruments was consistent with the observed damage in the downtown area of Napa. (Josh Edelson/AFP/Getty Images) Kids skateboard over buckled roads in a residential neighborhood of Napa. Much of the fault appears to be smoothly slipping (afterslip) with no stuck spots that would usually fail in aftershocks. LOS ANGELES _ In a land where the mildest rumble elicits an anxious question _ "Did you feel that?" Residential structures and wineries surrounding this area were significantly damaged. The epicenter was located approximately 9 km south of the city of Napa in northern California. 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 On August 24, 2014, a magnitude-6.0 earthquake occurred in Napa, California. (Public domain.). The red star is the location of the mainshock. The computed instrumental intensities agreed well with those reported by residents. map with 41,356 responses as of this writing. The magnitude 6.0 earthquake occurred early in the morning on August 24, 2014, on the West Napa Fault. The six traces are labeled A-F. In response to this earthquake, the Special Projects task of the National Earthquake Technical Assistance Program (NETAP) under FEMA Contract HSFE60-12-D-024 with the Applied Technology Council (ATC) It caused much damage and injured many. Following the South Napa Earthquake on August 24, 2014, the Earthquake Engineering Research Institute (EERI) convened a small team of researchers to develop an approach for studying the resilience of businesses impacted by major earthquakes. Damage to structures decreased with distance from the rupture. The crosses and letters indicated cross-sections not shown in this image. There was one fatality due to the earthquake, and at least $500 million in economic losses. 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. the sedimentary basin - soft sediments amplify the shaking. The change occurred within 1 hour after earthquake, but the discharge amount returned to normal within a few days. Some fault strands that broke in residential areas and damaged homes, had not previously been mapped. 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 dur-ing cleanup activities. “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. Residents in this area feel small earthquakes often, and they generally pause for a moment and then go back to whatever they were doing. (see directivity). Public domain. Key Recovery Factors for the August 24, 2014, South Napa Earthquake 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. Afterslip forecast hazard map of the Browns Valley neighborhood and surrounding area in Napa, Calif. 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. 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. Copy Link. (Josh Edelson/AFP/Getty Images) ... 2014. USGS Home Contact USGS Search USGS. USGS Geologists inspecting fault trace in a trench dug across one of the ruptures from the 2014 South Napa earthquake. No other surface features were found, such as evidence of liquefaction or landslides. 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 same could be said for the tornados in the midwest and south, and hurricanes in the southeast coastal areas. 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. The South Napa Earthquake caused extensive damage through both ground shaking and surface cracking (rupture). ), These two photos showing evidence of afterslip were taken where the fault crosses Highway 12 (south side of the highway) at Cuttings Wharf Road. Damaged unreinforced masonry building on Main St. in downtown Napa. (Public domain. A smaller magnitude 5.0 earthquake on the same fault had damaged the city of Napa in 2000. These recordings are being used, in part, to better understand the performance of residences and older masonry buildings that have been retrofitted. performance of buildings after earthquakes. 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. Ongoing fault movement along the surface rupture, called afterslip, continued for several months, and caused further damage to foundations and structures. Pavement buckling and tented sidewalk resulting from compressional forces at north end of main fault rupture, Sandybrook Lane, Napa California. Yountville, Vallejo, and American Canyon were also damaged. 1: In the event of a natural disaster such as an earthquake, City Inspectors will perform an Olivia Allen-Price. The shaking caused some damage to wood-frame houses and significant damage to some commercial buildings in downtown Napa, including the 1870 courthouse. 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. The August 24, 2014, South Napa earthquake (M6.0) produced significant damage resulting from shaking, fault rupture, fault afterslip, and ground deformation. It may extend further north or south and may connect with other fault zones. Data collected from airborne LIDAR were used to look for effects on the ground surface. tests for the 2014 South Napa earthquake. Over 41,000 people went online to report what they felt during the event. The South Napa earthquake along the San Andreas Fault reached 6.0, caused roughly $1 billion in damage, injured 200, killed one and jolted plenty of nerves. Copy Link. In the case of re trospective full-waveform inversions, a network with station spacing of 10km within the epicentral distanc e of 30km is able to provide adequate stable key source parameters if the preestimated hypocenter and fault ori entation are accurate of ±5km and ±15°, respectively. For further details, see Groundwater Effects from Earthquakes. The M6.0 South Napa earthquake occurred on August 24, 2014. This is not an unusual phenomenon in areas with natural springs and geothermal features. The sharp rise starting on August 24 reflects an increased streamflow due to the South Napa Earthquake. the wood-frame houses that were damaged were older ones that had not been retrofit (see links below for retrofitting information). Global predictions for localized events were posted on Astrosymm.com on 6/14/14. 2014 South Napa Earthquake Retrospective. With one fatality, and approximately a half billion dollars of economic damage, the city of Napa is still recovering from last year’s quake. It also had a large amount of afterslip, and fewer aftershocks than average for an earthquake of its size. Initially, the fault afterslip was rapid and extended into at least the southern part of the Browns Valley neighborhood in the city of Napa. A case study from the 2014 South Napa earthquake helps students make connections between interseismic strain and earthquake displacements. The Did You Feel It? 1: What does it mean if my apartment building was red, yellow, or green tagged*? It was the biggest temblor to hit the Bay Area since the M6.9 Loma Prieta earthquake of 1989. This event was of great interest to seismologists, especially at the Berkeley Seismolgical Laboratory. Damage to wood-frame houses was mostly broken or cracked chimneys and failure of cripple walls (see Additional Resources below), short walls in the crawl space between the foundation and the floor. The 24 August 2014 Mw 6.0 South Napa earthquake occurred on … These events are going to happen regularly. (Public domain. Previous smaller earthquakes in the area also triggered relatively few aftershocks for their size, suggesting that this area doesn’t produce many aftershocks. 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