Paleoseismic Investigation along the straight section of the central Altyn Tagh fault and its constrain on the rupture history

Abstract

Paleoseismic records are essential for constraining the earthquake recurrence behavior of active faults and evaluating the rupture history. However, paleoseismic studies on the central Altyn Tagh fault (ATF) are still scarce, and previous studies indicate that this fault section with simple geometry is not periodic. In addition, paleoseismic data from two sites along central ATF reveal different amounts of paleoearthquakes and present discordant in time. Therefore, we conducted paleoseismic studies and documented six reliable paleoseismic events at the LaPeiQuan site along the straight section of the central ATF. The results indicate that the most recent event is a small earthquake with a tiny vertical offset. The data A.D. (1752–1880) yr (event A) is significantly later than the last event along the Xorkoli section. The penultimate event at the LaPeiQuan site is a large earthquake for the ages of this event B is A.D. (667–764) yr (event B), which is consistent with the Xorkoli site and Aksay double bend site, producing at least 140 km rupture. In addition, the large vertical offset measurement from the deformed sediment of event B also supports its large one. The ages of Event D are discordant with the adjacent paleoseismic sites. The ages of Event C, Event E and Event F are still in process. The reason earthquake histories are inconsistent may be that small-scale geometrical complexities can prevent earthquake rupture propagation.