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A New Perspective on Fault Geometry and Slip Distribution of the 2009 Dachaidan Mw 6.3 Earthquake from InSAR Observations.

Liu Y, Xu C, Wen Y, Fok HS - Sensors (Basel) (2015)

Bottom Line: On 28 August 2009, the northern margin of the Qaidam basin in the Tibet Plateau was ruptured by an Mw 6.3 earthquake.We then propose a four-segmented fault model to investigate the coseismic deformation by determining the fault parameters, followed by inverting slip distribution.The inverted geodetic moment is 3.85 × 10(18) Nm (Mw 6.36).

View Article: PubMed Central - PubMed

Affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. Yang.Liu@sgg.whu.edu.cn.

ABSTRACT
On 28 August 2009, the northern margin of the Qaidam basin in the Tibet Plateau was ruptured by an Mw 6.3 earthquake. This study utilizes the Envisat ASAR images from descending Track 319 and ascending Track 455 for capturing the coseismic deformation resulting from this event, indicating that the earthquake fault rupture does not reach to the earth's surface. We then propose a four-segmented fault model to investigate the coseismic deformation by determining the fault parameters, followed by inverting slip distribution. The preferred fault model shows that the rupture depths for all four fault planes mainly range from 2.0 km to 7.5 km, comparatively shallower than previous results up to ~13 km, and that the slip distribution on the fault plane is complex, exhibiting three slip peaks with a maximum of 2.44 m at a depth between 4.1 km and 4.9 km. The inverted geodetic moment is 3.85 × 10(18) Nm (Mw 6.36). The 2009 event may rupture from the northwest to the southeast unilaterally, reaching the maximum at the central segment.

No MeSH data available.


Related in: MedlinePlus

Down-sampled interferogram data of descending track 319 (a) and ascending track 455 (b) using the quadtree decomposition algorithm. Positive values indicate motion away from the satellite along its LOS, while negative values indicate motion toward the satellite.
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sensors-15-16786-f003: Down-sampled interferogram data of descending track 319 (a) and ascending track 455 (b) using the quadtree decomposition algorithm. Positive values indicate motion away from the satellite along its LOS, while negative values indicate motion toward the satellite.

Mentions: We first use the InSAR data to determine the fault geometry with four segments, followed by solving for a more realistic slip distribution model. Before the inversion analysis, we resample the unwrapped interferometric phase (Figure 2) using the quadtree decomposition algorithm [34,35], a simple technique that is used to obtain an image representation at different resolution levels. For a given quadrant, if the variance is above a prescribed threshold (e.g., 9 mm2 in this study), the quadrant is then divided into four new quadrants. The process is iterated until either each quadrant has below-threshold variance, or until the quadrant reaches a minimum block size (e.g., 8 × 8 pixels in this study). After these processes, the numbers of the resampled interferogram data sets are reduced from 670,580 to 1229 for descending track 319, and from 517,910 to 1092 for ascending tack 455 (Figure 3). For each resampled observation point, variable Line-of-Sight (LOS) unit vectors are calculated precisely by considering observing geometry and topography. We also include an orbital ramp to model the residual orbit errors or long-wavelength atmospheric noise [25,33].


A New Perspective on Fault Geometry and Slip Distribution of the 2009 Dachaidan Mw 6.3 Earthquake from InSAR Observations.

Liu Y, Xu C, Wen Y, Fok HS - Sensors (Basel) (2015)

Down-sampled interferogram data of descending track 319 (a) and ascending track 455 (b) using the quadtree decomposition algorithm. Positive values indicate motion away from the satellite along its LOS, while negative values indicate motion toward the satellite.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541906&req=5

sensors-15-16786-f003: Down-sampled interferogram data of descending track 319 (a) and ascending track 455 (b) using the quadtree decomposition algorithm. Positive values indicate motion away from the satellite along its LOS, while negative values indicate motion toward the satellite.
Mentions: We first use the InSAR data to determine the fault geometry with four segments, followed by solving for a more realistic slip distribution model. Before the inversion analysis, we resample the unwrapped interferometric phase (Figure 2) using the quadtree decomposition algorithm [34,35], a simple technique that is used to obtain an image representation at different resolution levels. For a given quadrant, if the variance is above a prescribed threshold (e.g., 9 mm2 in this study), the quadrant is then divided into four new quadrants. The process is iterated until either each quadrant has below-threshold variance, or until the quadrant reaches a minimum block size (e.g., 8 × 8 pixels in this study). After these processes, the numbers of the resampled interferogram data sets are reduced from 670,580 to 1229 for descending track 319, and from 517,910 to 1092 for ascending tack 455 (Figure 3). For each resampled observation point, variable Line-of-Sight (LOS) unit vectors are calculated precisely by considering observing geometry and topography. We also include an orbital ramp to model the residual orbit errors or long-wavelength atmospheric noise [25,33].

Bottom Line: On 28 August 2009, the northern margin of the Qaidam basin in the Tibet Plateau was ruptured by an Mw 6.3 earthquake.We then propose a four-segmented fault model to investigate the coseismic deformation by determining the fault parameters, followed by inverting slip distribution.The inverted geodetic moment is 3.85 × 10(18) Nm (Mw 6.36).

View Article: PubMed Central - PubMed

Affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. Yang.Liu@sgg.whu.edu.cn.

ABSTRACT
On 28 August 2009, the northern margin of the Qaidam basin in the Tibet Plateau was ruptured by an Mw 6.3 earthquake. This study utilizes the Envisat ASAR images from descending Track 319 and ascending Track 455 for capturing the coseismic deformation resulting from this event, indicating that the earthquake fault rupture does not reach to the earth's surface. We then propose a four-segmented fault model to investigate the coseismic deformation by determining the fault parameters, followed by inverting slip distribution. The preferred fault model shows that the rupture depths for all four fault planes mainly range from 2.0 km to 7.5 km, comparatively shallower than previous results up to ~13 km, and that the slip distribution on the fault plane is complex, exhibiting three slip peaks with a maximum of 2.44 m at a depth between 4.1 km and 4.9 km. The inverted geodetic moment is 3.85 × 10(18) Nm (Mw 6.36). The 2009 event may rupture from the northwest to the southeast unilaterally, reaching the maximum at the central segment.

No MeSH data available.


Related in: MedlinePlus