Yushu Fault Research Articles

Timing of Holocene Surface‐Ruptures Across Adjacent Rupture‐Segments Where the Jinsha River Crosses the Yushu Fault, Qinghai Province, China

Timing of Holocene Surface‐Ruptures Across Adjacent Rupture‐Segments Where the Jinsha River Crosses the Yushu Fault, Qinghai Province, China

Holocene activity and seismic surface rupture zone of the Abuduo fault eastern Tibetan Plateau

The Garzê–Yushu fault is a large active NW-trending strike-slip fault on the Tibetan Plateau, along which strong earthquakes have frequently occurred historically. Together with the Xianshuihe fault, the Garzê–Yushu fault constitutes the northern boundary of the Sichuan–Yunnan block, and it is also the boundary between the Bayan Har and Qiangtang blocks. The Abuduo fault is a near E–W-trending fault on the southern side of the Garzê–Yushu fault. Through remote sensing image interpretation and field seismic geological investigations, this study found a series of left-lateral displacement landforms and well-preserved seismic surface rupture zones along the Abuduo fault, extending over a distance of approximately 65 km from Abuduo through Yushu and Qinghai to Selikou Village. According to the geological and geomorphological evidence, the Abuduo fault is considered a left-lateral strike-slip fault with Holocene activity, which has tectonic conditions suitable for breeding and generating strong earthquakes. Additionally, the eastward extension of the Abuduo fault is likely to intersect the Garzê–Yushu fault and thereby decompose its horizontal sliding deformation.

Source Parameter Inversion and Century-Scale Stress Triggering Analysis of the 2021 Maduo MW7.4 Earthquake Using GNSS and InSAR Displacement Fields

To explore the degree of constraint by Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data on the Maduo earthquake within a layered earth model structure and to gain an insight into the seismogenic mechanism and the seismic risk in the surrounding area, this study employs D-InSAR technology to acquire the InSAR co-seismic deformation field of the Maduo earthquake on 22 May 2021. Utilizing both GNSS and InSAR data, the inversions constrained by single and joint data are conducted and compared to determine the co-seismic slip model and fault plane stress distribution of the Maduo earthquake. Additionally, this paper calculates the Coulomb stress changes induced by 14 M ≥ 7 strong earthquakes, considering co-seismic effects, post-seismic viscoelastic relaxation, and inter-seismic tectonic stress loading, on 19 fault segments within the Bayan Har block research area (96°E~106°E, 29°N~36°N) since 1900. The findings are as follows: (1) The maximum line-of-sight (LOS) deformation was approximately 0.9 m. The joint inversion rupture was primarily located in the Dongcao Along Lake section (~98.6°E), aligning with previous research outcomes. (2) The cumulative Coulomb stress at the Maduo earthquake’s source location was −0.1333 MPa, while the inter-seismic stress loading amounted to 0.0745 MPa. The East Kunlun Fault, Maduo–Gande Fault, Ganzi–Yushu Fault, and Dari Fault C exhibited considerable stress loading, warranting attention due to heightened seismic risk. (3) Based on three different co-seismic slip models, the stress disturbance results caused by the Maduo earthquake to the surrounding area and fault did not differ significantly. After the earthquake, the seismogenic fault still has high seismic risk.

Reconstructing the Geometry of the Yushu Fault in the Tibetan Plateau Using TLS, GPR and Trenching

Although geomorphic evidence and shallow geometry of active faults are significant for the understanding and assessing of fault activity and seismic hazards, it is challenging to acquire high-resolution topographic data and shallow geometry of the Yushu fault by conventional methods. Here, we present a case study to reconstruct the detailed surficial and subsurface geometry of the Yushu fault using terrestrial laser scanning (TLS), multi-frequency ground penetrating radar (GPR) and trenching. TLS was suitable for measuring the high-resolution three-dimensional (3D) topographic data of the fault. GPR surveys with different frequency antennas (25 MHz, 100 MHz, 250 MHz and 500 MHz) were conducted to image the shallow geometry of active faults at different depths and spatial resolutions. The typical groove landscape, parallel to surface traces of the fault, was clearly observed on the TLS-derived data. A ~40 m width narrow fault system and three faults were identified on the different frequency GPR profiles. Furthermore, faults F1 and F2 were supposed to be boundary faults but were sinistral-lateral strike-slip faults with a normal component, while fault F3 was inferred as the secondary fault. The western trench section, despite the limited investigation depth (~2 m), was well consistent with the 500 MHz GPR result, especially in the location of fault F2. Finally, a 3D surficial and subsurface model was established from the TLS-derived data and GPR data offering multi-sensor and multi-view spatial data to characterize and understand the fault’s kinematics and characteristics. In addition, the shallow geometry of the fault on the GPR results would be better interpreted with the help of the corresponding surficial data. The study results demonstrate that a combination of TLS, multi-frequency GPRs and trenching can be successfully used for reconstructing a detailed surficial and subsurface geometry of the Yushu fault. It will play an increasing role in comprehensive understanding and assessing fault behavior and seismic hazards, especially on the Tibetan Plateau and the adjacent area.

Long-Term Spatial–Temporal Evolution of Seismicity of the 2010 Ms 7.1 Yushu, Qinghai, China Earthquake

On 14 April 2010, a destructive earthquake (Ms 7.1) occurred along the Ganzi–Yushu fault (GYF), which is the boundary between the Songpan–Ganzi and Qiangtang Blocks of the eastern Tibetan Plateau. In this study, we present an effective workflow for microearthquake detection and location that assembles three main methods including a graphics processing unit-based match and locate technology (GPU M&L), a deep-neural-network-based noise-reduction technique (DeepDenoiser), and a U-net-based phase picking method (PhaseNet). Following this workflow, a high-resolution catalog has been constructed based on continuous seismic data from 2008 to 2018 recorded by 13 seismic stations deployed by Qinghai seismic network in Yushu, Qinghai. The GPU M&L is first applied to detect earthquakes which are usually hard to pick by routine methods due to their low signal-to-noise ratios. Then the DeepDenoiser is applied to remove noises from events we detected by GPU M&L, providing a better picking of seismic phases. The PhaseNet and hypoDD are conducted to pick seismic phases and relocate detected events, respectively. The spatial–temporal evolution of the foreshock sequence of the Yushu earthquake suggests that a triggered cascade model is responsible for the nucleation of the mainshock. The mainshock and aftershocks southeast of the mainshock mainly rupture on the primary northwest (NW)-trending GYF while the foreshocks and aftershocks on the NW segment rupture along the northeast (NE)-trending fault normal to the strike of the GYF. The average cumulative slip rate of the GYF estimated from six repeating earthquakes is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.4~\pm ~1.7$ </tex-math></inline-formula> mm/year, which is consistent with the geodetic and geological observations.

Geological and geomorphological evidence of holocene activity along the maisu fault in the northern Sichuan–Yunnan block, Tibetan Plateau

The Sichuan–Yunnan block is located in the eastern of Tibetan Plateau and exhibits strong tectonic and earthquake activity. The Maisu fault is an E–W-trending fault within this block. Via interpretations of remote-sensing imagery and field surveys, we identified a earthquake surface rupture zone that has developed along the Maisu fault; we then estimated its Holocene activity. The surface rupture extends westward from the town of Puma, Sichuan Province, to the village of Worilong, Xizang Province, and has a length of approximately 45 km. According to a fault outcrop and carbon-14 dating of a profile near the village of Yongqu, Xizang Province, the most recent earthquake along this rupture may have occurred after 1850 ± 30 BP. The Maisu fault extends eastward and may intersect the Garzê–Yushu fault. Accordingly, as a secondary fault, the Maisu fault likely accommodates the partitioned horizontal slip deformation of the Garzê–Yushu fault.

Dating of multi-period earthquake-triggered rockfalls: a method for revealing paleo-seismic events that occurred along the Yushu fault in the eastern Tibetan Plateau

Dating of multi-period earthquake-triggered rockfalls: a method for revealing paleo-seismic events that occurred along the Yushu fault in the eastern Tibetan Plateau

Coulomb stress changes associated with the M7.3 Maduo earthquake and implications for seismic hazards

On May 21, 2021, the M7.3 Maduo earthquake occurred within the Bayan Har Block, one of the most seismically active regions in the Tibetan Plateau. This aroused attention to the seismic hazards in this block. Understanding the stress transfer to adjacent faults is important for assessing seismic hazards. In this study, based on the elastic dislocation theory and a multi-layered lithospheric model, we calculate the Coulomb failure stress changes caused by this event on the adjacent major faults and identify the segments that experienced significant increases in stress. Our preliminary results show that five segments, including the middle segment of the Dari Fault, the Tuosuo Lake segment, the Maqin–Maqu segment, the western segment of the Dari Fault, and the Yushu segment of the Garze–Yushu Fault, experienced significant increases in co-seismic stress, which exceed the proposed threshold (1 ​× ​104 ​Pa) for triggering an earthquake. The stress change pattern associated with the post-seismic viscoelastic relaxation effect is substantially consistent with that caused by the co-seismic effect. The segments with high combined (co-plus post-seismic) stress changes are identical to those indicated by the co-seismic stress increase. Based on the stress change in this study and those of previous studies on seismic activity and fault stress evolution, we emphasize the seismic potential of the Maqin–Maqu segment, the Tuosuo Lake segment, and the middle-west segments of the Dari Fault, which should receive increased attention.

Late quaternary slip rate of the east segment of the Yushu fault in the central-eastern Tibetan Plateau

The Yushu fault is a mainly left-lateral strike slip fault with some normal component within the Ganzi-Yushu fault system in central-eastern Tibetan Plateau. In 2010, the catastrophic Yushu Ms 7.1 earthquake occurred along this fault, causing approximately 3000 casualties and widespread damages; however, the late Quaternary slip rate of this fault was not tightly constrained due to poor research. Based on the interpretation of satellite images, field measurement of the offset of terrace risers, optically stimulated luminescence (OSL) and radiocarbon (14C) dating of terrace ages, the late Quaternary slip rate of the east segment of the Yushu fault is estimated to be 6.8–8.2 mm/yr. In consideration of the partitioning effect of the Batang fault south of Yushu, the late Quaternary slip rate of the entire Yushu segment is approximately 9–12 mm/yr. Given the characteristic offset of about 6–8 m, the recurrence interval of large earthquakes along the Yushu fault is estimated to be approximately 750–1150 yr. This research provides basic parameters for the long-term seismic hazards assessment of the Yushu area and implies the limited southeastward extrusion rate (~10 mm/yr) of Qiangtang block relative to the Bayan Har block.

Multi-frequencies GPR measurements for delineating the shallow subsurface features of the Yushu strike slip fault

In order to assess Ground penetrating radar (GPR) for imaging the shallow subsurface geometry and characteristics of the fault in Yushu area, details GPR measurements with 25 MHz, 100 MHz and 250 MHz frequencies antenna were firstly conducted in four sites along the Yushu fault after geomorphologic and geological investigation. The 25 MHz profiles delineated an excellent general view of deformation zones at a much wider area and greater depth. While the 100 MHz and 250 MHz data provided more detailed analysis of the shallow subsurface deformation about the geologic structure and the fault, including the stratigraphic structures, the dip angle and direction of the fault plane. The remarkable variation in the pattern and relative amplitude of electromagnetic waveform on the two-dimensional GPR profiles are all obvious and it is considered as the main fault zone with a nearly vertical fault with the dip angle of 70°–85°. High frequency GPR profiles show a good consistency with the trench sections at three sites. The geometry of the main fault zone can be depicted and deduced up to ~ 12 m deep or even deeper on the 25 MHz GPR profile in Yushu area and it is considered to be the result of the movement of active faults. What’s more, the geophysical features on GPR profile associated to the strike-slip fault are further summarized in different geological and geomorphological environment in Yushu area, the study also provides further evidence that GPR is valuable for fault investigation and palaeoseismic study in the Qinghai-Tibet Plateau area.

New insights into the 2010 Yushu Mw6.9 mainshock and Mw5.8 aftershock, China, from InSAR observations and inversion

The Mw6.9 Yushu earthquake occurred on 14 April 2010, in Qinghai, China; the largest aftershock, a Mw5.8 event, occurred west of the mainshock on 29 May 2010 (˜40 days later). The aftershock had a different focal mechanism from the mainshock. Furthermore, seismicity after 29 May showed different spatial characteristics in terms of focal depth and distribution direction. To better understand the faulting and the relationship between these two events, we derived the whole displacement field caused by the Yushu mainshock and the Mw5.8 aftershock based on multi-perspective Interferometric Synthetic Aperture Radar (InSAR) data. We then conducted a robust inversion of the slip distribution jointly constrained by InSAR and GPS data. The results indicate that the Mw5.8 aftershock produced a separated deformation field with significant displacement changes of up to ˜4–6 cm, which indicates another intersecting ruptured fault at the west end of the Yushu fault. The slip distribution shows a 75-km NW rupture with a maximum slip of ˜2.1 m at a depth of ˜0–10 km on the main Yushu fault, and a 20 km NE rupture with peak slip of ˜0.4 m at a depth of ˜5–15 km on a vertical hidden fault. Both events showed a dominant left-lateral component. The total rupture length associated with the 2010 Yushu earthquake sequence reached ˜95 km. By calculating Coulomb stress changes, we confirmed that the mainshock triggered the Mw5.8 aftershock. Our results imply that the increased stress at the western end of the Yushu fault caused by the mainshock rupture may have played an important role in transferring the rupture plane from the Yushu fault to the NE hidden fault.

Late quaternary slip behavior of the Yushu fault and the 2010 Ms 7.1 Yushu earthquake, eastern Tibetan Plateau

The 2010 Ms 7.1 Yushu earthquake generated a 30-km-long surface rupture along the Gyêgu segment of the Yushu fault within the eastern margin of the Tibetan Plateau. Comparison of the surface slip distribution from this earthquake with the cumulative slips provides a basis to examine repeated activity through several earthquake cycles along the Yushu fault. To better understand the seismic behavior of the Yushu fault, we conducted geomorphological and geological investigations on the 2010 slip and cumulative offsets along the fault at several typical sites. Field observation and satellite image interpretation shows that the coseismic surface ruptures typical of the 2010 Yushu earthquake are discontinuous and usually do not show distinct slip at places where the accumulated displacements are large. Measurements made both in the field and on the satellite images show that the surface slip of the 2010 event was comparatively small and contributed little to cumulative displacement of the fault. Repeated offsets of 6–8 m characterize slip associated with events prior to 2010 along the Yushu fault, whereas the 2010 earthquake produced offsets only on the order of 1 m. In addition, surface ruptures from the magnitude 7.1 event involved the failure of less than half of the Gyêgu fault segment and did not terminate at major geometrical and geological breaks in the fault zone. Geomorphic evidence implies that the fundamental behavior of the Gyêgu fault segment is typically expressed as full-length rupture activity. Thus, data from this study suggests that the characteristic slip along the Yushu fault is 6–8 m, the Ms 7.1 earthquake was not likely a characteristic event along the Yushu fault and the 2010-type events may make some contribution to the low slip rate and long recurrence interval of large earthquakes on the Yushu fault.

Deformation of the Most Recent Co‐seismic Surface Ruptures Along the Garzê–Yushu Fault Zone (Dangjiang Segment) and Tectonic Implications For the Tibetan Plateau

AbstractThe Garzê–Yushu strike‐slip fault in central Tibet is the locus of strong earthquakes (M &gt; 7). The deformation and geometry of the co‐seismic surface ruptures are reflected in the surface morphology of the fault and depend on the structure of the upper crust as well as the pre‐existing tectonics. Therefore, the most recent co‐seismic surface ruptures along the Garzê–Yushu fault zone (Dangjiang segment) reveal the surface deformation of the central Tibetan Plateau. Remote sensing images and field investigations suggest a 85 km long surface rupture zone (striking NW‐NWW), less than 50 m wide, defined by discontinuous fault scarps, right‐stepping en echelon tensional cracks and left‐stepping mole tracks that point to a left‐lateral strike‐slip fault. The gullies that cross fault scarps record systematic left‐lateral offsets of 1.8 m to 5.0 m owing to the most recent earthquake, with moment magnitude of about M 7.5, in the Dangjiang segment. Geological and geomorphological features suggest that the spatial distribution of the 1738 co‐seismic surface rupture zone was controlled by the pre‐existing active Garzê–Yushu fault zone (Dangjiang segment). We confirm that the Garzê–Yushu fault zone, a boundary between the Bayan Har Block to the north and the Qiangtang Block to the south, accommodates the eastward extrusion of the Tibetan Plateau and generates strong earthquakes that release the strain energy owing to the relative motion between the Bayan Har and Qiangtang Blocks.

Active tectonics of the Ganzi–Yushu fault in the southeastern Tibetan Plateau

The ongoing convergence between India and Eurasia apparently is accommodated not merely by crustal shortening in Tibet, instead also by motions along strike slip faults which are usually boundaries between tectonic blocks, especially in the Tibetan Plateau. Quantification of this strike slip faulting is fundamental for understanding the collision between India and Eurasia. Here, we use a variety of geomorphic observations to place constraints on the late Quaternary kinematics and slip rates of the Ganzi–Yushu fault, one of the significant strike-slip faults in eastern Tibet. The Ganzi–Yushu fault is an active, dominantly left-lateral strike-slip structure that can be traced continuously for up to 500km along the northern boundary of the clockwise-rotating southeastern block of the Tibetan Plateau. We analyse geomorphic evidence for deformation, and calculate the late Quaternary slip rates at four sites along the eastern portion of the fault trace. The latest Quaternary apparent throw rates are variable along strike but are typically ~1mm/a. Rates of strike-slip displacement are likely to be an order of magnitude higher, 8–11mm/a. Trenching at two locations suggests that the active fault behaviour is dominated by strike-slip faulting and reveals several earthquake events with refined information of timing. The 2010 Mw 6.9 Yushu earthquake, which occurred on the northwestern segment of the Ganzi–Yushu fault zone, provides additional evidence for fault activity. These observations agree with GPS-derived estimates, and show that late Quaternary slip rates on the Ganzi–Yushu fault are comparable to those on other major active strike-slip faults in the eastern Tibetan Plateau.

Compound Fault Rupture in the 2014 Ms 6.5 Ludian, China, Earthquake and Significance to Disaster Mitigation

A strong earthquake of M s 6.5 occurred on the margin of the Tibetan plateau in a rural area of Ludian county (Fig. 1a), northeastern Yunnan Province, China, at 16:30 (Beijing Standard Time) on 03 August 2014. The epicenter (103.3° E, 27.1° N) was located at the intersection of the northwest‐striking Baogunao–Xiaohe and northeast‐trending Zhaotong–Ludian faults (Fig. 1b). The focal mechanisms of the mainshock and four strong aftershocks (Fig. 2) showed that this was a high dip angle, sinistral strike‐slip event (http://www.eq-igl.ac.cn/wwwroot/c\_000000090001/d\_1406.html, last accessed August 2014; http://comcat.cr.usgs.gov/earthquakes/eventpage/usb000rzmg#scientific, last accessed September 2014; Fang et al. , 2014). As a result of this earthquake, 617 people died, 112 people were missing and presumed dead, 3143 people were injured, and many houses were damaged. Figure 1. (a) Southeastern margin of the Tibetan plateau. The white arrows show the Global Positioning System (GPS) velocity field of the Sichuan and Yunnan region with respect to the South China reference frame (modified from Zhang, 2013). ANHF, Anninghe fault; ZMHF, Zemuhe fault; DLSF, Daliangshan fault; and DBPF, Dien Bien Phu fault. The red stars (Fig. 1a–c) show the epicenter of the Ludian M s 6.5 earthquake. (b) The tectonic map of earthquake disaster areas (modified from http://www.eq-igl.ac.cn/wwwroot/c\_000000090001/d\_1406.html; last accessed August 2014); the dashed black rectangular box indicates the area of Figure 2. (c) The inset figure shows the Tibetan plateau and its adjacent area. ALTF, Altyn Tagh fault; HYF, Haiyuan fault; KLF, Kulun fault; GZYS, Ganzi–Yushu fault; LMSF, Longmenshan fault; RRF, Red River fault; and SAGF, Sagaing fault. The dashed white rectangular box indicates the area of Figure 1a. The dashed blue rectangular box indicates the area of Figure 1b. Figure 2. Distribution of landslides and precise relocation of the Ludian M s 6.5 earthquake sequences. The precise relocation …

Late Quaternary slip rate of the Batang Fault and its strain partitioning role in Yushu area, central Tibet

The late Quaternary activity of Yushu segment is poorly understood compared with other segments within Ganzi–Yushu Fault system. We focused on the Batang Fault, a major branch fault of the Yushu segment. Interpretation of remote sensing images and field investigations reveals that this fault has a clear geomorphic expression which is characterized by prominent fault escarpment and systematically offset gullies, fluvial terraces and alluvial fans along strike. Morphotectonic mapping, combined with optically stimulated luminescence (OSL) and radiocarbon (14C) data, suggest that the Batang Fault is a late Holocene active left-lateral strike-slip fault, along with some reverse component. The average left-lateral slip rate of this fault is 2–4mm/yr and vertical slip rate is 0.2–0.6mm/yr since Late Pleistocene. Comparison with the slip rates of other faults within the Ganzi–Yushu Fault system demonstrates that the Batang Fault partitioned nearly a third of the strike slip deformation within Yushu segment. This study provides insights into the reasons why the Yushu Fault is relatively less active when compared with other segments within Ganzi–Yushu Fault system and is crucial to the seismic hazard assessment in Yushu area especially after the occurrence of 2010 Ms 7.1 Yushu earthquake.

Late Pleistocene–Holocene paleoseismology of the Batang fault (central Tibet plateau, China)

The Yushu segment of the Ganzi–Yushu fault system (central Tibet plateau) is mainly composed by the Yushu fault and the Batang fault. The 2010 Ms 7.1 Yushu earthquake occurred on the Yushu fault, causing huge loss of lives and widespread damages to the densely populated Yushu area. So far, much effort has been devoted to the surface rupture and paleoseismology of the Yushu fault, while the late Quaternary activity of the Batang fault has not received much attention. The Batang fault has a clear geomorphic expression with fault scarps, sag ponds, push-ups, systematic offset of fluvial terraces, and alluvial fans along its trace. Integrated methods of geomorphological mapping, outcrop analysis, trench excavation and logging, optically stimulated luminescence (OSL), and radiocarbon (14C) dating are employed to study the latest Pleistocene and Holocene paleoseismology of the Batang fault. Several paleoearthquakes are identified from geomorphic and stratigraphic evidence between 22ka and after 2.7ka. The oldest event (E1) occurred after 22kaBP, E2 prior to 14kaBP, E3 within 14 and 9.5kaBP, E4 within 8.0–7.8kaBP, E5 prior to 6.7kaBP, the penultimate event (E6) occurred within 4.3–4.0kaBP, and the most recent event (E7) occurred after 2.7kaBP. The average recurrence interval of paleoearthquakes for the Batang fault is about 2000a in the last ~8kaBP, and the relapse time of the latest paleoearthquake is <2.7ka. Co-seismic displacement of the most recent surface-rupturing event is about 3m, as deduced from the offsets of the youngest terrace risers and of small gullies. Empirical equations between co-seismic displacement and earthquake magnitude reveal that the average magnitude of these events is about 7.3. This study contributes important information for the seismic hazard assessment of the densely populated Yushu area.

Velocity contrast along the rupture zone of the 2010 Mw6.9 Yushu, China, earthquake from fault zone head waves

Fault zone head waves (FZHWs) travel along the bimaterial fault interface and can be used to provide high-resolution imaging of fault zone properties. Here we use aftershock data following the 2010/04/13 Mw6.9 Yushu earthquake to quantify velocity contrast along the Garzê–Yushu Fault (GYF). FZHWs are identified as low-amplitude, long-period seismic signals with polarities opposite to the direct P arrivals. We observe FZHWs at 4 stations near faults that bound both sides of the Jielong basin, which is a pull-apart basin that is partially filled by Longbao Lake. The time delays between the direct P and FZHWs increase systematically with along-strike distances, and the corresponding observed velocity contrast is on the order of 5–8%. However, we do not observe a clear increase of time delay with hypocentral depth, suggesting that the pull-apart basin forms a thick low-velocity zone that likely exists in the top few kilometers of the crust. The velocity contrast southeast of the mainshock epicenter is very small (1–3%), consistent with both field observations and seismic tomographic results.

Timing and Spouting Height of Sand Boils Caused by Liquefaction during the 2010 Mw 6.9 Yushu Earthquake, Tibetan Plateau, China

The 2010 Mw 6.9 Yushu earthquake produced a ~33-km-long co-seismic surface rupture zone along the pre-existing active Yushu Fault on China’s central Tibetan Plateau. Sand boils occurred along the tension cracks of the co-seismic surface rupture zone, and locally spouted up above the ground to coat the top of limestone blocks that had slid down from an adjacent ~300-m-high mountain slope. Based on our observations, the relations between the arrival times of P- and S-waves at the sand-boil location and the seismic rupture velocity, we conclude that 1) the sand boils occurred at least 18.24 s after the main shock; 2) it took at least 4.09 - 9.79 s after the formation of co-seismic surface rupture to generate liquefaction at the sand-boil location; 3) the spouting height of sand boils was at least 65 cm. Our findings help to clarify the relationships between the timing of lique-faction and the spouting height of sand boils during a large-magnitude earthquake.

The MW 6.9 14 April 2010 Yushu Earthquake and a 10,000‐Year Record of Paleoseismicity along the Guoqiong Segment of the Yushu Fault, Qinghai Province, China

The M_W 6.9 14 April 2010 Yushu Earthquake and a 10,000‐Year Record of Paleoseismicity along the Guoqiong Segment of the Yushu Fault, Qinghai Province, China