Changes in Seismic-Moment Rates along the Rupture Zone of the 1964 Great Alaska Earthquake

Variability of megathrust earthquakes in the world revealed by the 2011 Tohoku-oki Earthquake

“…Although the aftershock activity in and around the Kodiak asperity can also be found in Fig. 3, the seismic moment release of the Kodiak asperity was much smaller than that of the PWS asperity (Johnson et al, 1996;Doser et al, 2006). These are consistent with the strong initial break (Wyss and Brune, 1967) of the 1964 Alaska earthquake and the ADDS type of rupture patterns similar to the 2011 megathrust, which can be clearly distinguished from the 1707, 1960 and 2010 earthquakes.…”

“…There were no prior earthquakes in the trench-ward region of the aftershock area of the 1964 Alaska earthquake, but strong activity in the hypocentral area in the land-ward region could be found before the earthquake. Two asperities of the 1964 Alaska earthquake where there are areas of large seismic moment release compared to the surroundings and which are considered to be areas of strongly-coupled plate interface were known as the Prince William Sound (PWS) asperity and the Kodiak asperity (e.g., Doser et al, 2006), respectively, to the eastern and western parts of the aftershock area. Aftershocks spread over the area, including the two asperities, implying that the seismic segment is not necessarily the same as the asperity but, rather, a spatial extent of the aftershock areas, including an asperity and its surrounding.…”

“…Seismic absence along the Chile trench and the Nankai trough implies the smooth and strongly-coupled zone along the subduction. Recent GPS observations by Freymueller et al (2008) and seismic moment release along the rupture zone of the 1964 Alaska earthquake (Doser et al, 2006) reveal a strong variability along the strike of the Alaska and the Aleutian arc. These are the similarities between the 1964 Alaska and 2011 Tohoku-oki megathrusts, the latter of which was discussed in Section 2.…”

Rupture process of the 1964 Prince William Sound, Alaska, earthquake from the combined inversion of seismic, tsunami, and geodetic data

“…The locked zones are coincident with areas of high seismicity along the megathrust and in the upper plate off the coast of Kodiak Island and beneath PWS and low seismicity over zones of low plate coupling [e.g., Doser et al, 2002;Zweck et al, 2002]. Doser et al [2002Doser et al [ , 2006 also observed different seismicity patterns between the PWS and KI locked zones. The PWS exhibits down dip migration of seismicity but the KI region does not exhibit down dip seismicity perhaps due to the differences in subducted terranes.…”