2010 Yushu Ms7.1 Earthquake Crack Filling Filling Light Dating

An accurate dating of paleo-earthquake places a significant role in constructing the history of earthquake and forecasting its future, and optically stimulated luminescence(OSL) is one of them. A controversy exists in the application of OSL dating to the paleo-earthquake Since mainly concerning about the solar resetting issue that may be associated with the massive and instaneously deposited sediments. The Ms7.1 Yushu earthquake adjacent to the Ganzi-Yushu fault, April 14, 2010 should be a good chance to study the solar resetting of sediment that fills in the seismic fractures(abbreviated as infill). In our study, infill in the seismic fracture was collected, as well as insitu the sediments that are at the same depth as infill and their solar resetting were analyzed by comparing their ages. In this case, the feasibility was explored in our study. It comes to the following conclusions:1. Sample LBHX1-4 and LBHX1-5collected from No.1 trench to the west of Longbao lake yielded1.95±0.08 ka and 2.50±0.10 ka. Sample LBHX1-2 and LBHX1-6(in situ at the same depth as LBHX1-4 and LBHX1-5) turned 2.53±0.10 ka 、1.95±0.07 ka, which indicates the OSL ages of infill were consistent with the one of in situ samples at the same depth. The ages of sample LBHX1-1, LBHX1-2 and LBHX1-3 near No.1 trench to the west of Longbao lake(the insitu samples) were1.65±0.09 ka, 2.53±0.10 ka and 2.81±0.3ka from top to bottom, which were in order.2. Sample LBHX2-1, LBHX2-2 and LBHX2-3 from No.2 trench to the west of Longbao lake were 1.29±0.07 ka, 2.83±0.1ka and 4.15±0.3ka from to bottom.3. Probably because the original sediments old, samples at Naliku trench and Changu Hydropower trench reached to 6.69±0.2ka(NLK1-2) and 17.75±0.53Gy(CGSDZ1-2). Therefore, it will be a big errorto adopt the age of theinfillat places like Naliku and Changu Hydropower trench to constraint a paleo-earthquake younger than 60 ka.4. OSL ages from four trenches including No.1, No.2, Naliku and Cangu Hydropower trenches showed thatthe solar didn’t reset well in the 2010 Yushu earthquake.5. It is feasibility that A consistence exists in the ages of infill and insitu sediments from trench No.1 and No.2 to the west of Longbao lake and they were all younger than 2.53±0.1ka, indicating that samples on the top of the infill or the in-situ sediments at the depth is suitable to timing a paleo-earthquake older than 25 ka(within the reasonable errors for OSL dating: OSL 5%-10%).6. Considering that earthquake may cause certain grains solar reset well, a single grain method would be adopted in the furture, and a reliable age for paleo-earthquake would be acquired.