1/15/2024 0 Comments Alaska quake depth![]() ![]() The government hydrologist tied it all together only after several area well-drillers called in, asking whether all the turbidity complaints they were getting could have anything to do with the big Alaskan earthquake. Risser could find no possible links to lunar tides or atmospheric pressure changes. Risser, at the Geological Survery office in Harrisburg, Pa., also was puzzled at first that more than a dozen of the 70 observation wells his office tracks by computer had recorded small, but sudden changes in water levels Nov. "It didn't really make any sense," Reichart said.ĭennis W. The calls were coming from Adams and York counties in Pennsylvania and northern Carroll County in Maryland. 3 tremor - just 6 miles deep - trigger abundant low-frequency waves, whose motions are largely restricted to the surface rocks, he said. "They can traverse all the way through the Earth's core and come out the other side."īut shallow earthquakes like the Nov. High-frequency seismic waves penetrate deep into the Earth, he said. The magnitude 8.1 Mexico City quake in 1985 killed more than 10,000.Įvery earthquake unleashes a mix of seismic waves, or vibrations, all traveling at different speeds, into the surrounding rock, said Anthony Qamar, a research associate professor of geophysics at the University of Washington. But no one was killed, and injuries were few in the remote, sparsely populated region closest to the quake's epicenter.īy comparison, the magnitude 7.8 quake in San Francisco in 1906 claimed 3,000 lives and $524 million in property losses. Highways were torn, store shelves were tossed, and the Trans-Alaska Pipeline was damaged, triggering a precautionary shutdown.ĭamage was estimated at $20 million. Photographs of the aftermath of the NovemM7.Uncounted landslides occurred in Alaska.US Geological Survey: Earthquake preparedness information.UAF Geophysical Institute: General earthquake information.Three seismometers are located within the park, and other efforts to install portable seismometers or instruments regarding the movement or nature of the earth’s crust are ongoing.įor additional information on seismology of the Denali or Alaska, visit: The park supports active research on seismic activity, and collaborates with the Alaska Earthquake Information Center (AEIC) and other groups to better monitor and understand the seismic activity in and near the park. Although the park area only suffered spilled shelf items and a few road sags, at other locations about 166 km (100 miles) east of the park, roads were fractured, several homes were jostled off their foundations, and the Trans-Alaska oil pipeline lost some of its support members. ![]() 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. The M7.9 was the largest earthquake to occur in the interior of the state in recorded history. On October 23, and November 3, 2002, the park and most of central and southern Alaska experienced a foreshock of M6.3, and a mainshock of M7.9. Historically, seismic events have not been known to damage man-made structures within the park. In November and early December of the year 2000, two earthquakes occurred on the north boundary of the park at M5.7 and M5.0, which shook local residences, and was felt as far away as Fairbanks. On May 21, 1991, a M6.1 earthquake occurred at a depth of 112 km right under Denali, and was noticed by climbing teams on the mountain who reported numerous massive snow and ice avalanches. Larger magnitude events (>M4.5) are not common in the park, but records show that a few have occurred. Generally, the highest magnitude events that occur in the park in any given year are in the neighborhood of the mid to high M4’s, and again, are often right under Denali or near the Kantishna Hills on the Northwest side of the park. Numerous faults, including the Denali fault (a major fault system), demonstrate a long history of active plate tectonics and associated earthquake activity. This seismic activity at the root of Denali suggests that uplift of the mountain continues to this day. A large share of earthquake activity is right under Denali, frequently, at very deep locations (90 – 125 km/54-75 miles deep), providing few people the opportunity to experience them. But these events are not usually felt by anyone because of the low magnitudes. ![]() Most of these earthquakes (about 70%), average between M1.5 and M2.5, and often occur near the surface (0-15 km/0-9 miles deep) at locations all over the Park. It is estimated that there are some 600 seismic events per year within the park boundaries at magnitude 1 (M1) or greater. Because of active plate tectonics, earthquakes are frequent in the Denali area. ![]()
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