Mid-crustal detachment and ramp faulting in the Markham Valley, Papua New Guinea

摘要: Earthquakes and geodetic evidence reveal the presence of a low-angle, mid-crustal detachment fault beneath Finisterre Range that connects to steep ramp surfacing near Ramu-Markham Valley Papua New Guinea. Waveforms three large (M w 6.3 6.9) thrust earthquakes occurred in October 1993 10 30 km north valley 15° north-dipping thrusts at about 20 depth. Global Positioning System measurements show up cm coseismic slip across valley, requiring active extend within few hundred meters Earth9s surface Markham Valley. Together, these data imply gently middle or lower crust steepens shallows southward, forming side indicate both were during least one earthquakes. While seismic potential detachments elsewhere is debated, Guinea shows capability producing