Recent california earthquakes1/5/2024 These studies have helped reveal the long-term earthquake and tsunami potential of the eastern Aleutian megathrust. Altogether, paleoseismic observations narrate the history of past earthquakes-their location, size, and recurrence-and validate geophysical models that simulate earthquake rupture and tsunami inundation.įrom 2010 to 2021, we conducted paleoseismic studies by excavating, describing, and sampling Holocene sediments in coastal environments at 16 sites spanning 1,800 kilometers between the Fox Islands and Prince William Sound (Figure 1). The timing and pace of past events can be estimated with dating methods, like radiocarbon analyses of spruce needles or fragments of salmon vertebrae. Such evidence includes signs of sudden land uplift or subsidence caused by earthquake deformation, of scoured landforms and layered sand deposits left behind by tsunami inundations, and of landslides or underwater slumps triggered by strong shaking. Coastlines along subduction margins above megathrusts are the most accessible places to search for evidence of prehistoric subduction zone earthquakes and tsunamis. Subduction megathrusts-huge, gently dipping reverse faults that form where one tectonic plate dives below another-extend from deep-sea trenches to hundreds of kilometers beneath overlying islands or continents. ![]() ![]() So how can we get better at preventing future disasters by anticipating and mitigating the impacts of tsunamigenic earthquakes? The answer involves digging into the coastal stratigraphic record to extend our knowledge of great earthquakes and tsunamis farther back in time. Yet providing hazard forecasts is crucial considering that Alaskan tsunamis endanger coastal communities around the Pacific Rim, including densely populated parts of Southern California and the shorelines of Hawaii. Similarly, the single century of instrumentally recorded great ( M w> 8) Alaska-Aleutian earthquakes is too short a period on which to base forecasts of these earthquakes and their accompanying tsunamis in the future. Providing hazard forecasts is crucial considering that Alaskan tsunamis endanger coastal communities around the Pacific Rim, including densely populated parts of Southern California and the shorelines of Hawaii. The 2011 earthquake illustrated starkly that brief historical records alone are inadequate indicators of potential future fault behavior. At the time, earthquake and tsunami hazard assessments in Japan relied primarily on instrumental records and written documents from time spans far shorter than the recurrence intervals (time elapsed between major events) of extreme earthquakes and tsunamis, which can span several centuries. ![]() A year later came an even bigger surprise: Japanese officials did not anticipate the scale and devastating impacts of the 2011 M w 9.1 Tōhoku earthquake, or of the resulting tsunami and meltdowns at the Fukushima nuclear power plant, which together constitute the most financially costly disaster in human history. Subduction zones around the world continue to surprise: For example, the 2010 M w 7.8 Mentawai earthquake caught the world off guard because it broke the shallow portion of the Sunda megathrust fault directly above a larger rupture in 2007 and because it triggered an unexpectedly large tsunami for the size of the earthquake. The unexpectedly distant and fatal consequences of the 1946 tsunami instigated the formation of the U.S. This wave destroyed the Scotch Cap lighthouse on nearby Unimak Island, Alaska, and killed 159 people in Hawaii, 3,750 kilometers away. For example, the moment magnitude ( M w) 8.6 Unimak Island earthquake in 1946 heaved up the seafloor, generating a tsunami that reached 42 meters in height. ![]() Between 19, nearly the entire 3,300-kilometer length of the Alaska-Aleutian subduction zone ruptured in a sequence of powerful, tsunami-generating earthquakes.
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