scholarly journals Supplemental Material: Geophysical analysis of the 30 July 1972 Sitka, Alaska, earthquake sequence

2020 ◽  
Author(s):  
Juan A. Ochoa Chavez ◽  
Diane Doser
Keyword(s):  
Earthquake Sequence ◽  
Double Difference ◽  
Alaska Earthquake

Supplemental Material 1 contains relocated aftershocks of 30 July 1972 sequence. Supplemental Material 2 contains relocation parameters used in double-difference algorithm (HYPODD).<br>

Supplemental Material: Geophysical analysis of the 30 July 1972 Sitka, Alaska, earthquake sequence

2020 ◽  
Author(s):  
Juan A. Ochoa Chavez ◽  
Diane Doser
Keyword(s):  
Earthquake Sequence ◽  
Double Difference ◽  
Alaska Earthquake

Supplemental Material 1 contains relocated aftershocks of 30 July 1972 sequence. Supplemental Material 2 contains relocation parameters used in double-difference algorithm (HYPODD).<br>

scholarly journals Supplemental Material: Geophysical analysis of the 30 July 1972 Sitka, Alaska, earthquake sequence

2020 ◽  
Author(s):  
Juan A. Ochoa Chavez ◽  
Diane Doser
Keyword(s):  
Earthquake Sequence ◽  
Double Difference ◽  
Alaska Earthquake

Supplemental Material 1 contains relocated aftershocks of 30 July 1972 sequence. Supplemental Material 2 contains relocation parameters used in double-difference algorithm (HYPODD).<br>

The Application and Research of the Double Difference Method about Regional and Telseismic Earthquake

2012 ◽  
Vol 622-623 ◽  
pp. 1651-1654
Author(s):  
Ba Teer Wu ◽  
Er Gen Gao ◽  
Ye Wu
Keyword(s):  
Travel Time ◽  
Basic Principle ◽  
Difference Method ◽  
Earthquake Sequence ◽  
Double Difference ◽  
Earth Model

The paper rests on the basic principle of the double difference method, through using Kennett and Engdahl(1991)’s IASPEI Earth model which can be used in computation theoretical travel time in the condition of regional and telseismic earthquake .We have developed a double difference program which can be used in the regional and teleseismic earthquake. And utilizes this program to relocate the Jiashi Ms 6.8 earthquake sequence in Xinjiang province on 24/2/2,003, obtained a quite good result.

The Application and Research of the Double Difference Method about the 2004 Ludian Earthquake Sequence

2013 ◽  
Vol 726-731 ◽  
pp. 3123-3127
Author(s):  
Ba Teer Wu ◽  
Er Gen Gao ◽  
Ye Wu
Keyword(s):  
Difference Method ◽  
Conclusive Evidence ◽  
Earthquake Sequence ◽  
Double Difference ◽  
Time Data ◽  
Earthquake Forecast ◽  
Earthquake Parameters ◽  
Ludian Earthquake ◽  
The North ◽  
North And South

The paper is utilizes the double difference method of to relocate the north and south earthquake belt's Ludian earthquake sequence to obtained the Ludian earthquake sequence's detailed earthquake parameters. And at the same time we have established an whole set of perfect method in data processing and result analysising. Have the ability of useing'the north and south earthquake belt earthquake to strengthen the monitor's real time data to accuratly relocate the medium intensity earthquake sequenc of the north and south belt. Thus,we could produce the more accurate earthquake parameter, and short provides a more conclusive evidence into the warning area division and earthquake forecast.

The Earthquake’s Relative Location Algorithms Effected by Data Recorded at Nearby Station

2012 ◽  
Vol 588-589 ◽  
pp. 1988-1998
Author(s):  
Ba Teer Wu ◽  
Er Gen Gao
Keyword(s):  
Difference Method ◽  
Earthquake Sequence ◽  
Double Difference ◽  
Relative Location ◽  
The Absolute ◽  
Simulated Calculation ◽  
Hypocenter Depth ◽  
Distant Station

Based on the primary theory of location, it is found that the data recorded at nearby stations are applicable in double difference relocation algorithm, but not in other relative location algorithms. Equation derivation and simulated calculation demonstrate that double difference algorithm allows to get the absolute locations of earthquakes with certain accuracy by using the nearby stations records. The errors of relative location become larger when using the nearby station records alone than that using the distant station records. Combining the nearby and distant station records, the best locations are obtained. In the case that hypocenter depth is far less than the epicenter distance without depth phases available, only the relative epicenter distribution could be obtained accurately by double difference method, the depth determined would be not stable. The relocation test of a part of aftershocks in Jiashi earthquake sequence verify the effect of nearby station records on the double difference algorithm mentioned above.

The 2003 Ms6.1 Minle Earthquake: An Earthquake in the Minle-Yongchang Reverse Fault-Related Fold Belt in the Hexi Corridor, NW China

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaobo Zou ◽  
Daoyang Yuan ◽  
Yanxiu Shao ◽  
Xingwang Liu ◽  
Weipeng Ge ◽  
...  
Keyword(s):  
Hexi Corridor ◽  
Earthquake Sequence ◽  
Stereo Image ◽  
Double Difference ◽  
Deformation Pattern ◽  
Reverse Fault ◽  
The Tibetan Plateau ◽  
Seismogenic Fault ◽  
Waveform Cross Correlation ◽  
Dip Angle

The Minle-Yongchang fault is an active reverse fault-related fold structural belt developed in the Hexi Corridor Basin on the northeastern edge of the Tibetan Plateau. An earthquake of Ms6.1 occurred near the Minle-Yongchang fault zone in 2003. The deformation pattern of the Minle-Yongchang fault and its relationship with this strong earthquake, however, are still not well known. In this study, we used the methods of HYPOINVERSE absolute location and double-difference location with waveform cross-correlation technology to relocate the 2003 Minle earthquake sequence. In total, 383 earthquakes are precisely relocated. Based on the results of precise seismic relocation, using the method of determining fault planes by small earthquakes, the seismogenic fault is found to be a low-angle thrust with a strike of 311°, a dip of NE, and a dip angle of 14°. It does not rupture the surface, extends to 19–20 km depth, and is hidden beneath the Yonggu Anticline. We also employed the cut-and-paste (CAP) method with a broadband waveform to determine the focal mechanism of the mainshock in 2003: the strike is 311°; the dip is 34°; and the rake is 90°. The fault plane parameters obtained in these two ways are roughly consistent. We also used a digital elevation model (DEM) derived from the SPOT 6 stereo image pair and high-precision differential Global Positioning System (GPS) to measure the displacement of terraces. Topographic profiles along the terraces across the Minle-Yongchang fault show that high alluvial terrain exhibits fold deformation. The vertical offsets of the T2 and T3 terraces along the Tongziba River are approximately 2.3 and 22 m, respectively. Optically stimulated luminescence (OSL) dating indicates that the ages of T2 and T3 are 11.3 and 106 ka, respectively. We calculated an average uplift rate of 0.21 ± 0.05 mm/a by dividing the vertical offset by age. According to the spatial distribution of the relocated earthquake sequence and terrace deformation in the study area, the Ms6.1 Minle earthquake in 2003 was caused by the latest activity of a blind reverse fault-related fold in the Hexi Corridor Basin.

Fluids Triggered the 2021 Mw 6.1 Yangbi Earthquake at an Unmapped Fault: Implications for the Tectonics at the Northern End of the Red River Fault

2022 ◽  
Author(s):  
Quan Sun ◽  
Zhen Guo ◽  
Shunping Pei ◽  
Yuanyuan V. Fu ◽  
Yongshun John Chen
Keyword(s):  
Source Region ◽  
High Stress ◽  
Red River ◽  
Earthquake Sequence ◽  
Rupture Zone ◽  
Double Difference ◽  
Data Set ◽  
Upward Migration ◽  
Velocity Models ◽  
Red River Fault

Abstract On 21 May 2021 a magnitude Mw 6.1 earthquake occurred in Yangbi region, Yunan, China, which was widely felt and caused heavy casualties. Imaging of the source region was conducted using our improved double-difference tomography method on the huge data set recorded by 107 temporary stations of ChinArray-I and 62 permanent stations. Pronounced structural heterogeneities across the rupture source region are discovered and locations of the hypocenters of the Yangbi earthquake sequence are significantly improved as the output of the inversion. The relocated Yangbi earthquake sequence is distributed at an unmapped fault that is almost parallel and adjacent (∼15 km distance) to the Tongdian–Weishan fault (TWF) at the northern end of the Red River fault zone. Our high-resolution 3D velocity models show significant high-velocity and low-VP/VS ratios in the upper crust of the rupture zone, suggesting the existence of an asperity for the event. More importantly, low-VS and high-VP/VS anomalies below 10 km depth are imaged underlying the source region, indicating the existence of fluids and potential melts at those depths. Upward migration of the fluids and potential melts into the rupture zone could have weakened the locked asperity and triggered the occurrence of the Yangbi earthquake. The triggering effect by upflow fluids could explain why the Yangbi earthquake did not occur at the adjacent TWF where a high-stress accumulation was expected. We speculate that the fluids and potential melts in the mid-to-lower crust might have originated either from crustal channel flow from the southeast Tibet or from local upwelling related to subduction of the Indian slab to the west.

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