However, full ANSS instrumentation on either end of the 2002 rupture is critical if this goal is to be achieved. BACKGROUNDER • ASSESSING AND MANAGING SEISMIC RISK. Hayes through the Alaska Range, and the ovals are the epicenters of two earthquakes, the magnitude 6.7 earthquake of Oct. 23, 2002, and the Denali Fault earthquake of Nov. 3, 2002. It was evident, during damage assessment evaluations after the Denali fault event, that the residents of the smaller at-risk communities had little understanding of the earthquake hazard, had not implemented measures to mitigate damage, and were unprepared to respond to the consequences of damage. There have been smaller earthquakes in … To send these continuous ground motion data to a central location for analysis, AEIC also operates radio repeaters within the park at Double Mountain, Mount Healy, and the Murie Science and Learning Center. Every event is briefly reviewed by the on-duty seismologist, and carefully relocated by an analyst. The largest surface offsets of 8.8 meters (29 feet) were observed farther to the east. Until then, the fault can be studied by measuring the steady deformation of the Earth that surrounds all active faults. It illuminates earthquake mechanics and hazards of large strike-slip faults. Largest aftershocks of the Nenana Mountain earthquake were the two magnitude 3.8 events. Most people in Interior Alaska were reminded of the fault’s earthquake potential when it ruptured on November 3, 2002. Earthquake forecasting and prediction is an active topic of geological research. The chances of experiencing shaking from an earthquake and/or having property damage is dependent on many different factors. Deep earthquakes occur under the ground in the southern and eastern portions of the park (see red-orange and orange dots on the map above). earthquake, which would result in a maximum PGA of 0.17g at Pebble. The AEIC located over 1,000 aftershocks of the M 6.7 event prior to the M 7.9 mainshock and over 35,000 aftershocks through the end of 2004. Analysts also scan waveforms to find earthquakes that were not detected by the automated system. Abstract An earthquake can be described as natural phenomena that cause shaking or trembling of the earth’s surface. The 2002 M7.9 Denali fault earthquake resulted in 340 km of ruptures along three separate faults, causing widespread liquefaction in the fluvial deposits of the alpine valleys of the Alaska Range and eastern lowlands of the Tanana River. Although the biggest earthquakes occur where plates rub together, some faults only become apparent when an earthquake occurs. April 9 2004 Rev F Page 1 Oil and Water System Performance – Denali M 7.9 Earthquake of November 3, 2002 By John Eidinger1 and Mark Yashinsky2 1.0 Introduction The November 3, 2002, magnitude 7.9 Denali, Alaska earthquake struck through rural Alaska. During this reporting period, the NEHRP celebrated its 25th anniversary. But once in awhile, we experience larger earthquakes too; in 1868, Kaʻū experienced a quake estimated at M 7.9 that knocked down every wall and building in the district, and took the lives of 81 … A real earthquake on the Hayward Fault could occur at any time and with a different pattern of shaking. In addition, CAST, KTH, and MCK are instrumented with accelerometers to measure ground acceleration. Once a fault has been identified, the next step is to determine how it behaves. of the Denali fault earthquake, with clockwise rotation ranging from about 14 in the western part of the rupture to as much as 38 in the eastern part. The southern edge of our state is an active tectonic plate boundary where the Pacific plate subducts (i.e., dives beneath) the North American plate along the great Alaska-Aleutian Megathrust. With more than 20,000 earthquakes reported annually, Alaska is by far the most seismically active state. Motion on the Denali Fault and nearby related fault structures is responsible for many of the large earthquakes in central Alaska, and for the high elevation (20,310 feet, 6190 meters) of Denali (previously known as Mt. Overall, motions were about 20 times faster over the first 1-2 years after the earthquake, compared to the pre-earthquake rates. Postseismic deformation results from different physical processes, including continued slip on the fault plane or its deeper extension and viscous flow in the Earth’s mantle. The Denali Fault, the fastest moving and most active fault in Interior Alaska, cuts through the heart of the Alaska Range and Denali National Park and Preserve. Areas affected by liquefaction are largely confined to Holocene alluvial deposits, man-made embankments, and backfills. of the Denali fault earthquake, with clockwise rotation ranging from about 14 in the western part of the rupture to as much as 38 in the eastern part. The AEIC located over 1,000 aftershocks of the M 6.7 event prior to the M 7.9 mainshock and over 35,000 aftershocks through the end of 2004. Therefore, in the pre-earthquake phase, preparedness, mitigation and prevention The 434 mile slip-strike fault gave off a 7.9 magnitude earthquake. Earthquake hazards Ground Rupture Alaskan pipe after the Denali quake ruptured through Ground rupture from the M8.1 2001 Tibet earthquake Earthquake hazards (cont.) To monitor seismic activity, staff from the Alaska Earthquake Information Center (AEIC) install and operate seismic stations across the state. About Cookies, including instructions on how to turn off cookies if you wish to do so. The major plates move relative to each other at rates that are typically a few centimeters per year, which is easily measured using GPS. Earthquakes shake the ground daily, but most are minor local events. One example of a major fault is the Denali fault, which cuts across the state in the Alaska Range (labelled on map on reverse). By continuing to browse this site you agree to us using cookies as described in About Cookies.. The evaluation of the seismic risk is considered essential to define strategic urban and emergency planning management actions and should be based on the analysis of the buildings, the exposed population and their emergency interaction. The 2002 Denali Fault earthquake caused changes in the observed motions all across central Alaska. At many of the sites inside the park, the motions after the 2002 earthquake are now slowing down to nearly the preearthquake rates. underground fault. 19 Cascadia: Paradigm Shift (1984-87) 1976 1990 1996 PGA (%g) with 2% PE in 50 years On average, Alaska has had one M 8+ earthquake every 13 years, one M 7-8 earthquake every two years, and six M 6-7 earthquakes per year (Alaska Seismic Hazards Safety Commission, 2012). Areas of active faulting like central Alaska continuously undergo slow deformation between earthquakes, and experience sudden shifts when earthquakes happen. G. Carver, G. Plafker, M. Metz et al., “Surface rupture on the Denali Fault interpreted from tree damage during the 1912 Delta river Mw 7.2–7.4 earthquake: implications for the 2002 Denali Fault earthquake slip distribution,” Bulletin of the Seismological Society of America, vol. 6, pp. The 2002 M7.9 Denali fault earthquake resulted in 340 km of ruptures along three separate faults, causing widespread liquefaction in the fluvial deposits of the alpine valleys of the Alaska Range and eastern lowlands of the Tanana River. Mitigating earthquake risk in Australia M.R. A network of 26 1-Hz GPS stations that observed sur-face wave displacements due to the Denali Fault event High precision Global Positioning System (GPS) surveying can now measure positions of survey points with a precision of a few millimeters. The section of the Denali fault cutting across the park has not experienced a major earthquake within the last ~100 years. We map the 385-kilometer (km) long surface trace of the right-lateral, strike-slip Denali Fault between the Totschunda-Denali Fault intersection in Alaska, United States and the village of Haines Junction, Yukon, Canada. Complex, powerful motions of tectonic plates and crustal blocks generate earthquakes throughout Alaska, including many in and around Denali National Park and Preserve. Proceedings of the Sixth U.S. Conference and Workshop on Lifeline Earthquake Engineering, TCLEE 2003: Advancing Mitigation Technologies and Disaster Response, held in Long Beach, California, August 10-13, 2003. Areas affected by liquefaction are largely confined to Holocene alluvial deposits, man-made embankments, and backfills. The evaluation of the seismic risk is considered essential to define strategic urban and emergency planning management actions and should be based on the analysis of the buildings, the exposed population and their emergency interaction. [2004] determined focal mechanisms for earthquakes before and after the Denali fault earthquake, then estimated A T eleseismic Study of the 2002 Denali Fault, Alaska, Earthquake and Implications for Rapid Strong-Motion Estimation Chen Ji,a) Don V .Helmber ger,a) and Da vid J.W ald, b) M.EERI Slip histories for the 2002 M7.9 Denali fault, Alaska, ear thquak e are de-rived rapidl y from global teleseismic w avefor m data. Using the program FPFIT [Reasenberg and Oppenheimer, 1985], Ratchkovski et al. The pattern of shallow, intermediate, and deep events in south-central Alaska highlights the shallow angle of the subduction. A major earthquake along the fault could cause the pipeline to rupture, spilling crude oil into the surrounding environment. Mitigating this damage is thus of paramount importance in reducing the overall risk posed by earthquakes. The Nenana Mountain and Denali Fault earthquakes generated a vigorous aftershock sequence. Larger earthquakes tend to shake longer and harder and therefore cause more damage to structures1. Scientists use these data to study what drives the motion on the fault, and to make estimates of the long-term rate of motion of the Denali Fault through the park. As crustal blocks slide horizontally past one another, strike slip faults occur; when blocks are pushed together, one block is thrust up or down along the fault line. Note how the blue dots scattered at the top of the map track roughly northeast-trending parallel lines. This was never more evident than in the fall of 2002, when two large earthquakes occurred. The section of the fault in the park is just as active as the section to the east, and at some point in the future it will also break in a large earthquake. These trained individuals greatly enhanced our State Post-Disaster Damage Assessment team's capability and credibility. It was the largest inland earthquake to hit North America in the last 150 years. practice into seismic risk reduction. Each seismic station transmits data to Fairbanks, where seismologists continuously monitor ground motion. The basic structure of methods for estimating hazard was developed by engineers needing quantitative answers despite the wide range of uncertainties ( 1 ). The Denali Fault has a lower seismic risk, with a maximum It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip … 2 San Andreas ... Denali fault, Alaska Magnitude 7.9 2002 ... 2004 2010 2011. The focus of our investigation was to characterize the spatial extent and amplitude of ground failures and fault displacements, and assess damage to structures. Lasted 10 minutes (longest lasting earthquake in history) 229,866 dead, which includes 42,883 missing. 1–3), which began with thrust faulting on a 48-km length of the previously unknown Susitna Glacier Thrust Fault. The Denali fault earthquake (Mw = 7.9) of November 3, 2002 was the largest strike–slip earthquake (Eberhart-Phillips et al., 2003) that occurred in North America in almost 150 years. Hazard estimates have important implications for society, providing a basis for building codes, insurance rate structures, risk assessments, and public policies to mitigate earthquake risk. Automatic locations are available within five minutes on AEIC’s webpage. Effect of the Denali Fault Rupture on the Trans-Alaska Pipeline ; Response of the Above-Ground Trans-Alaska Pipeline to the Magnitude 7.9 Denali Fault Earthquake ; Assessment of the Below-Ground Trans-Alaska Pipeline Following the Magnitude 7.9 Denali Fault Earthquake 3 November 2002 Denali Fault earthquake, a large-magnitude (M=7.9) shallow strike-slip event, generated large-amplitude surface waves observable by GPS to a distance of thousands of kilometers [Larson et al, 2003]. Earthquakes cause lots of damage to property and even result in deaths. View at: Google Scholar Water in pools, ponds, and bayous as far away as Texas and Louisiana splashed for nearly half an hour. Even several years after the earthquake, average speeds remain several times higher than the pre-earthquake rates at many sites. One example of a major fault is the Denali fault, which cuts across the state in the Alaska Range (labelled on map on reverse). and minor earthquakes on the subduction zone in a cluster pattern. Geoscientists are able to identify particular areas of risk and, if there is sufficient information, to make probabilistic forecasts about the likelihood of earthquakes happening in a specified area over a specified period. The November 3, 2002 Denali fault earthquake, which is the largest inland event ever recorded in central Alaska, occurred along an arcuate segment of the right‐lateral strike‐slip Denali fault. The 1964 Good Friday Earthquake is an example. The more stress that builds up across a fault, the larger the earthquake is when that stress is released. BACKGROUNDER • ASSESSING AND MANAGING SEISMIC RISK. The typical example of this kind of earthquake was the Hyogoken Nambu Earthquake in 1995, the Niigataken Chuetsu Earthquake in 2004, and the Noto Hanto Earthquake in 2007. For example, there were clusters of earthquakes around a zone that included a major earthquake on Jan 30, 1973, another cluster around an earthquake of March 14, 1979, and two more cluster around earthquakes of July 1957 and January, 1962. Each of these seismic stations is instrumented with a broadband seismometer to detect ground motion, a data digitizer to record displacement, a radio to transmit the data, and solar panels to help power the equipment. As the stress mounts along the Denali fault in the park, and as more time elapses without the stress release of a strong earthquake, the probability of a big earthquake in the park continues to rise. Earthquake forecasting and prediction is an active topic of geological research. Called the Denali Fault earthquake, this shock was the strongest ever recorded in the interior of Alaska. This seismically active area in the heart of the park typically experiences a M 2 earthquake every few days. This TCLEE Monograph presents 107 state-of-the-art papers on the effects of natural and technological hazards on lifelines. COUNTERMEASURES AGAINST LARGE-SCALE EARTHQUAKES The main cause of many casualties in the Hyogoken Nambu Earthquake in 1995 was Although the fault there shifted about 14 feet, the pipeline did not break, averting a major economic and environmental disaster. Alaska is the most geologically active part of the United States. The cause? [4] The Denali fault earthquake had 340 km of surface rupture and was the largest strike-slip earthquake in North The epicenter was located west of Nenana Mountain on the Denali fault… These quakes are associated with the northern extension of the subduction edge of the Pacific plate and its dive beneath the North American crust. One of them was the Denali 7.9 earthquake, the largest earth- However, the duration of shaking associated with a magnitude 9.2 mega-thrust earthquake would be longer, and this is also factored into the seismic evaluations. All the atmospheric parameters [CWV, SLHF, relative humidity (RH) and total ozone column (TOC)] show significant changes prior and after the Denali fault earthquake. During the afternoon of November 3, 2002, the water in Seattle’s Lake Union suddenly began sloshing hard enough to knock houseboats off their moorings. The epicenters (point on the earth surface where the quakes originate) of each of these large earthquakes was about 50 km (30 miles) east of the park, on the Denali fault. Eastern Denali Fault surface trace map, eastern Alaska and Yukon, Canada. Studies of the fault at various locations have yielded a wide range of slip rates, but the best estimates generally converge on a maximum rate of about 10 mm/yr. The Denali Fault extends across the heart of the Alaska Range, passing just north of the town of Cantwell, through the Muldrow Glacier at the base of the north face of Denali, and continues to the west. Such knowledge is needed to predict ground motions in future earthquakes so that earthquake-resistant structures can be designed. Before allowing the installation of scientific equipment in a national park (via research permit), staff from the park conduct an impact study and provide a period for public comment. earthquakes, including the 1964 Prince William Sound 9.2 earthquake. It can last for years to decades after a large earthquake, and its changes with time provide important information about the physical properties of the Earth. The M W (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. On November 3, 2002 a devastating earthquake rattled Alaska. Many nations in the Indian Ocean were not aware of “tsunami” Absence of a Tsunami Early Warning Systems Major earthquakes (those with a magnitude range of 7.0-7.9) occur where a significant amount of stress has accumulated prior to being released—along a plate boundary or along major faults. Geologic observations from the Denali fault could prove invaluable to mitigating earthquake risk and saving lives in Alaska and elsewhere. In the Aleutian Islands, where the subduction angle is much steeper, the shallow-todeep earthquake pattern is more compact. We map the 385-kilometer (km) long surface trace of the right-lateral, strike-slip Denali Fault between the Totschunda-Denali Fault intersection in Alaska, United States and the village of Haines Junction, Yukon, Canada. Earthquake Hazards Mitigation Here on the Big Island, we feel small earthquakes on a regular basis, and magma movement underground that precedes eruptive activity produces low-level tremor. Denali National Park is located very close to the Denali fault. The red line represents the fault, which runs east toward Mt. California’s Earthquake Risk Shifting Focus: A Look at California’s Earthquake Risk. ... slightly larger than the magnitude 9.0 Sumatra-Andaman Islands earthquake that devastated northern Sumatra in December 2004 and generated a tsunami that killed more than 280,000 people. The Nenana Mountain and Denali Fault earthquakes generated a vigorous aftershock sequence. Seismicity in interior Alaska north of the Denali fault is dominated by shallow events (see blue dots on map above). The Denali Fault earthquake sequence resulted in about 340 km of surface rupture (Haeussler and others, 2004) (figs. The Good Friday Earthquake—a 1964 magnitude 9.2 event located in Prince William Sound—remains the largest earthquake ever recorded in the U.S. and the secondlargest earthquake ever recorded worldwide. On average, Alaska has had one M 8+ earthquake every 13 years, one M 7-8 earthquake every two years, and six M 6-7 earthquakes per year (Alaska Seismic Hazards Safety Commission, 2012). Earthquake Risk in Alaska. The Totschunda fault splays off of the Denali fault to the southeast, and may be part of a developing connection between the plate-bounding Queen Charlotte-Fairweather and western Denali faults [Richter and Matson, 1971]. [2004] determined focal mechanisms for earthquakes before and after the Denali fault earthquake, then estimated Following the Mw 7.9 earthquake on the Denali and Totschunda faults on 3 November 2002, we conducted a reconnaissance of the region to investigate geotechnical and surface rupture features of the event. To understand the risk that different areas of the U.S. face for earthquake hazards, we need to know where faults are and how they behave. > $7 billion dollars damage Reasons for huge loss….. The 800-mile-long Trans-Alaska Pipeline, which starts at Prudhoe Bay on Alaska’s North Slope, can carry 2 million barrels of oil per day south to the port of Valdez for export, equal to roughly 10% of the daily consumption in the United States in 20171. Earthquake - Earthquake - Methods of reducing earthquake hazards: Considerable work has been done in seismology to explain the characteristics of the recorded ground motions in earthquakes. The main shock occurred about 80 km (50 miles) east of the Denali Visitor Center. The earthquake caused an offset of nearly 6 meters (20 feet) where it crossed the Richardson Highway and Trans-Alaska Pipeline. Shortly after midday on November 3, 2002, a magnitude 7.9 earthquake ruptured the Denali Fault in the rugged Alaska Range, about 90 miles south of Fairbanks. Within the park, he sets up an instrument to record data at each survey point for a few days each year, and uses these year-to-year changes in position to study the movements of the Earth. On October 23, people of Interior Alaska were awakened to strong shaking caused by a magnitude 6.7 earthquake. Large earthquakes like this one cause significant displacements of the surface far away from the fault. As the effects of the 2002 earthquake continue to dissipate, continued measurements of GPS sites in and around the park will provide an invaluable record of how the crust and mantle in central Alaska behave. According to Ford, “The Denali Fault earthquake was the ‘big one’ for Alaska.” The cracks in the Earth’s surface along parts of the fault were up to 6.7 meters (22 feet) wide, which would have caused considerable damage to a more heavily populated area, such as California. Such approach is urgently needed for complex scenarios, like the historical one, but still, in many cases around the world, historical centers scenarios are not properly investigated according this holistic risk analysis standpoint. Alaska has experienced four federally declared disasters from November 2002 to August 2003. Fortunately, no one was seriously injured, due to the small population located OCLC Number: 64385498: Notes: Title from Web page (viewed Feb. 24, 2006). This presents a rare opportunity to catch a major earthquake in the act. Although earthquakes cause death and destruction through such … In 2002, the M 7.9 earthquake ruptured a portion of the Denali fault east of the park to produce a horizontal offset of up to 8.8 m (29 feet). Movement at shear zones have generated up to magnitude (M) 7.3 earthquakes. We know a fault exists only if it has produced an earthquake or it has left a recognizable mark on the earth’s surface. Similarly, the largest recorded earthquake in North American history also occurred on a subduction zone fault … Edwards, M. Rahman, H. Ryu, ... the second was close to the community of Mundaring east of the Darling fault. Postseismic deformation is the general term used for the movements that follow and are triggered by earthquakes. The destruction caused by an earthquake depends on the magnitude and … Continue reading "Mitigation of Earthquakes" Earthquakes can cause impacts far from their source. In 2002, a magnitude 7.9 earthquake struck the Denali fault, one of the lar… around the Denali fault is sparsely populated, it is the same type of fault as the San Andreas fault in California, which is surrounded by densely populated cities. Geologist Wes Wallace of the University of Alaska s Geophysical Institute took this photo of the Denali Fault before the earthquake. In 2002, the M 7.9 earthquake ruptured a portion of the Denali fault east of the park to produce a horizontal offset of up to 8.8 m (29 feet). The earthquake caused an offset of nearly 6 meters (20 feet) where it crossed … Large earthquakes often cause considerable damage to infrastructure and structures. AEIC analysts locate between 20,000 and 30,000 earthquakes in Alaska each year. After large earthquakes, the pattern and rate of strain around the fault is often quite different immediately after the earthquake compared to the pre-earthquake time period. The interaction of the Pacific and North American plates across southern Alaska creates a variety of sources for seismic activity. al., 1994]. Measurements Freymueller has made across the Alaska Range before the 2002 earthquake show movement across the Denali Fault of 6-8 millimeters per year (1/4 to 1/3 inch per year). In phases, three models Although people tend to view the Earth as static and stable between earthquakes, every point is actually moving slowly as Earth’s tectonic plates move around. The November 2002 earthquake had a magnitude of 7.9 and caused a surface rupture 325 km (~200 miles) long, mostly on the central Denali Fault (see red line on map below). Alaska’s Denali Fault was on the move, jostling the state with a magnitude 7.9 earthquake. Largest aftershocks of the Nenana Mountain earthquake were the two magnitude 3.8 events. The Kantishna cluster is a group of small, shallow earthquakes—not far from Wonder Lake—at the southwestern end of a shear zone. The earthquake lasted about 100 seconds. It is unknown whether some of this stress is being relieved by the cluster of frequent shallow earthquakes in the Kantishna area. November 2002, the powerful magnitude 7.9 Denali Fault earthquake struck south-central Alaska, rupturing the ground beneath the zigzagging Trans-Alaska Oil Pipeline. Denali fault earthquake to evaluate structural damage in that event. Ongoing tectonic processes are constantly shifting and changing the land. S58–S71, 2004. McKinley) that dominates the park landscape. Real time ground motion data from ~400 seismic stations across the state are used to identify and characterize each earthquake in Alaska. AEIC has four seismic stations in Denali: (from west to east, see map) Castle Rocks (CAST), Kantishna Hills (KTH) on Wickersham Dome, Thoroughfare Mountain (TRF), and McKinley (MCK) near the park entrance. The Denali Fault has a lower seismic risk, with a maximum The earthquake began about 80 km (50 miles) east of the Denali Visitor Center, and ruptured eastward along the Denali Fault, and was followed by thousands of aftershocks. However, the duration of shaking associated with a magnitude 9.2 mega-thrust earthquake would be longer, and this is also factored into the seismic evaluations. Mitigation Pacific Nankai h Metropolitan 3. Effect of the Denali Fault Rupture on the Trans-Alaska Pipeline ; Response of the Above-Ground Trans-Alaska Pipeline to the Magnitude 7.9 Denali Fault Earthquake ; Assessment of the Below-Ground Trans-Alaska Pipeline Following the Magnitude 7.9 Denali Fault Earthquake 94, no. Remove maintenance message For example, the Tohoku, Japan, earthquake of 2011 occurred on a subduction zone fault and it was over magnitude 9, making it one of the largest earthquakes ever recorded. Using the program FPFIT [Reasenberg and Oppenheimer, 1985], Ratchkovski et al. Measuring the deformation of the earth related to this tectonic activity helps scientists understand the 2002 earthquake and the tectonic forces that caused it. ATTACHMENT SEMINAR ON DENALI FAULT EARTHQUAKE Lloyd Cluff and Norm Abrahamson Pacific Gas and Electric Company Date: January 23, 2004 Place: One White Flint North Building, 11555 Rockville Pike, Rockville, MD 20852 The 2002 Denali EQ, the Trans-Alaska Oil Pipeline and EQ Hazard Mitigation On Nov 3, 2002 a large magnitude 7.9 earthquake happened along the Denali fault, about 160km south of Fairbanks/Alaska. The Denali Fault earthquake sequence began with the 23 October 2002 Mw6.7 Nenana Mountain foreshock, followed on 3 November 2002 by the Mw7.9 Denali Fault mainshock. For better understanding of all the possibilities of earthquake risk reduction, it is important to classify them in terms of the role that each one of them could play. Eastern Denali Fault surface trace map, eastern Alaska and Yukon, Canada. The pipeline crosses the Denali fault some 90 miles south of Fairbanks. The earthquake began about 80 km (50 miles) east of the Denali Visitor Center, and ruptured eastward along the Denali Fault, and was followed by thousands of aftershocks. It was the main fault along which the 2002 Denali earthquake occurred, which was measured as a magnitude of 7.9 M w. During the afternoon of November 3, 2002, the water in Seattle's Lake Union suddenly began sloshing hard enough to knock houseboats off their moorings. The criteria consisted of location, type, and amount of fault displacement at the Denali and other fault crossings. Investigating the seismic response of regular and irregular urban structures can provide useful information for input to any preparedness plan. Geoscientists are able to identify particular areas of risk and, if there is sufficient information, to make probabilistic forecasts about the likelihood of earthquakes happening in a specified area over a specified period. The National Hazard Maps use all available data to estimate the chances of shaking (of different strengths and All measurement sites, including those in the park, initially showed rapid horizontal motions, which have slowed down over time. OCLC Number: 64385498: Notes: Title from Web page (viewed Feb. 24, 2006). The longest earthquake ruptures on strike-slip faults, like the San Andreas Fault (1857, 1906), the North Anatolian Fault in Turkey (1939) and the Denali Fault in Alaska (2002), are about half to one third as long as the lengths along subducting plate margins, and those along normal faults are even shorter. Investigating the seismic response of regular and irregular urban structures can provide useful Information for to... Motions were about 20 times faster over the first 1-2 years after the earthquake in that event that all! Faults only become apparent when an earthquake occurs two magnitude 3.8 events Ratchkovski et al by shallow events ( blue... 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