These people tend to get water from private wells, heat their homes and cook their meals with gas furnaces and stoves, and maintain individual septic systems. Several bridges were damaged but none so severely that they were closed to traffic.ĭue to the general self-sufficiency of those living near the fault rupture, very few lifeline systems were compromised. Minor damage was reported over a wide area but the only examples of severe damage were on highways that crossed the fault trace and areas that suffered liquefaction, e.g. On the Denali fault itself, there were fewer and smaller aftershocks than expected, with the largest only being a M w 5.8 event. Many aftershocks were actually on faults nearby that are not known to have ruptured, and may just be accommodating stress changes. South of Denali, aftershocks match the inferred characteristics of the Susitna Glacier thrust. Aftershocks Īftershocks primarily manifested in portions of fault where surface rupture was found, and aftershocks were usually limited to very shallow depths.
There is evidence of local supershear propagation inferred from ground motions along at least 35 km (22 mi) of the rupture. The total seismic moment of this earthquake corresponds to a magnitude of M w 7.9. The second, an M w 7.3 subevent, ruptured along the Denali fault, while the third, final, and largest M w 7.6 subevent continued past the second event along the Denali and Totschunda faults where the maximum displacements of 8.8 m (29 ft) was observed. Three subevents were observed during the event: the first was a M w 7.2 primarily thrust event along the Susitna Glacier thrust with potential simultaneous Denali fault rupture. Two areas of high seismic moment were observed 70 km (43 mi) and 200 km (120 mi) from the epicenter. The transition zone between the Denali fault and the Totschunda fault which includes small normal faults had a peak displacement of 2.7 m (8 ft 10 in), while the main Totschunda fault slipped an average of 1.5 m (4 ft 11 in) with a peak of 2.1 m (6 ft 11 in) found. Slip on the Denali fault peaked at 8.8 m (29 ft) with an average slip of 5.3 m (17 ft). Slip on the Susitna Glacier thrust peaked at 4 m (13 ft) with an average displacement of 1.4 m (4 ft 7 in) across the fault. The rupture then jumped to the main Denali Fault strand propagating for a further 218 km (135 mi) before jumping again onto the Totschunda Fault through a wide and complex transition zone, and then ruptured another 70 km (43 mi) of fault plane. The initial rupture on November 3, nucleating 22 km (14 mi) east of the foreshock, was on a thrust fault segment, the previously unknown Susitna Glacier thrust, to the south of the Denali fault. The calculated stress transfer from this foreshock indicates that it brought the Denali fault closer to failure at the location of the mainshock epicenter. Because of its location close to the November 3 event and the fact that it preceded it by only 11 days, this earthquake is regarded as a foreshock. Minor avalanches of snow and rockfalls were plenty in the area as a result. This rupture extends to 10 km (6.2 mi) west of the mainshock's epicenter. The event's aftershocks revealed a 45 km (28 mi) long fault rupture along the Denali fault, but aerial reconnaissance could not locate a surface rupture. On October 23, 2002, there was a magnitude 6.7 earthquake located on the Denali fault. The Denali-Totschunda fault system is one of the structures that accommodate the accretion of the Yakutat terrane. In Alaska, moving from east to west, the plate interactions change from a transform boundary between Pacific and North American plates to a collision zone with a microplate, the Yakutat terrane, which is in the process of being accreted to the North American plate, to a destructive boundary along the line of the Aleutian islands. The Denali-Totschunda fault is a major dextral (right lateral) strike-slip system, similar in scale to the San Andreas fault system. About 20 houseboats were damaged by a seiche on a lake in Washington State. Due to the remote location, there were no fatalities and only one injury.ĭue to the shallow depth, it was felt at least as far away as Seattle and it generated seiches on bodies of water as far away as Texas and New Orleans, Louisiana. The shock was the strongest ever recorded in the interior of Alaska. This 7.9 M w earthquake was the largest recorded in the United States in 37 years (after the 1965 Rat Islands earthquake). The 2002 Denali earthquake occurred at 22:12:41 UTC (1:12 PM Local Time) November 3 with an epicenter 66 km ESE of Denali National Park, Alaska, United States. Extent of surface rupture caused by faulting during the 2002 Denali earthquake
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