Probing the Fault Complexity of the 2017 Ms 7.0 Jiuzhaigou Earthquake Based on the InSAR Data

On 8 August 2017, a surface wave magnitude (Ms) 7.0 earthquake occurred at the buried faults extending to the north of the Huya fault. Based on the coseismic deformation field obtained from interferometric synthetic aperture radar (InSAR) data and a series of finite fault model tests, we propose a brand-new two-fault model composed of a main fault and a secondary fault as the optimal model for the Jiuzhaigou earthquake, in which the secondary fault is at a wide obtuse angle to the northern end of the main fault plane. Results show that the dislocation distribution is dominated by sinistral slip, with a significant shallow slip deficit. The main fault consists of two asperities bounded by an aftershock gap, which may represent a barrier. In addition, most aftershocks are located in stress shadows and appear a complementary pattern with the coseismic high-slip regions. We propose that the aftershocks are attributable to the background tectonic stress, which may be related to the velocity-strengthening zones.

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Inversion of the Slip Distribution of the 2017 Ms7.0 Jiuzhaigou Earthquake From InSAR

10.21203/rs.3.rs-125202/v1 ◽

2020 ◽

Author(s):

Xiongwei Tang ◽

Rumeng Guo ◽

Jianqiao Xu ◽

Heping Sun ◽

Xiaodong Chen ◽

...

Keyword(s):

Tectonic Stress ◽

Fault Model ◽

Slip Distribution ◽

Obtuse Angle ◽

Coseismic Deformation ◽

Jiuzhaigou Earthquake ◽

The North ◽

Finite Fault ◽

Main Fault ◽

Secondary Fault

Abstract On 8 August 2017, an Ms 7.0 earthquake occurred on a buried fault extending to the north of the Huya fault. Based on the coseismic deformation field obtained from Interferometric Synthetic Aperture Radar (InSAR) data and a series of finite fault model tests, we proposed a brand new two-fault model composed of a main fault and a secondary fault as the optimal model for the Jiuzhaigou earthquake, in which the secondary fault is at a large obtuse angle to the northern end of the main fault plane. Results show that the slip distribution is dominated by sinistral slip, with a significant shallow slip deficit. The main fault consists of two asperities, which is bounded by an aftershock gap may representing a barrier. In addition, we find that most of the aftershocks were located down-dip of the high-slip areas and laid in stress shadows. We deduce that the aftershocks may be controlled by the background tectonic stress field, and may be related to the velocity-strengthening zones.

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Slip-deficit estimation with a 3D fault model of the North Anatolian Fault by using InSAR time series

10.5194/egusphere-egu21-14513 ◽

2021 ◽

Author(s):

Alison Seidel ◽

Henriette Sudhaus

Keyword(s):

Time Series ◽

Crustal Deformation ◽

Time Series Data ◽

Fault Model ◽

North Anatolian Fault ◽

Series Data ◽

The North ◽

Slip Deficit ◽

Finite Fault ◽

Finite Fault Model

Crustal earthquakes are events of sudden stress release throug&#173;h rock failure, for example as a consequence of continuous and long-term stress buildup at tectonic faults that eventually exceeds the strength of rock. Before failure, under increasing stress at a fault, the surrounding crust is slowly deforming. The amount and pattern of crustal deformation carries information about location and potential magnitude of future earthquakes.Time series of space-borne interferometric Synthetic Aperture Radar (InSAR) data can be used to precisely measure the surface motion, which corresponds to the crustal deformation, in the radar line-of-sight and across large areas. These observations open the opportunity to study fault loading in terms of location, size of locked parts at faults and their slip deficit. Here we study the North Anatolian Fault (NAF), a major right-lateral strike-slip fault zone of about 1500 km length in the north of Turkey and we create its first large-scale 3D finite-fault model based on InSAR data.We use the InSAR time series of data recorded by ESA&#8217;s Envisat SAR satellite between 2002 and 2010 (Hussain et al., 2018 and Walters et al., 2014). We represent the fault with several vertical, planar fault segments that trace the NAF with reasonable resolution. The medium model is a layered half space with a viscoelastic lower crust and mantle. Several GNSS velocity measurements are used to apply a trend correction and calibrate the InSAR time series data to an Eurasia-fixed-reference frame. We use the plate motion difference of the Anatolian and the Eurasian plates calculated through an Euler pole to set up a back-slip finite-fault model. We then optimize the back-slip as the slip deficit, the width and the depth of the locked fault zone at each segment to achieve a good fit to the measured surface motion.We find shallow locking depths and small slip deficits in the eastern and westernmost regions of the NAF, while the central part shows both deeper locking depths and larger slip deficits for the observation period. For both parameters the trends are in an overall agreement to earlier studies. There, InSAR-time series data have been used to calculate slip deficits at the North Anatolian fault with 2D models and/or assuming a homogeneous and purely elastic medium. Local modeled differences therefore might be connected to differences in the modeling approaches, but also remain subject to further investigations and discussions.Our model provides a very suitable basis for future time-dependent modeling of the slip deficit at the NAF that includes also more recent InSAR time series based on data from the Sentinel-1 radar satellite mission of ESA.

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Simulation of the MW = 7.9 Gulf of Alaska earthquake on January 23, 2018, by the stochastic finite fault model

Acta Geophysica ◽

10.1007/s11600-021-00562-0 ◽

2021 ◽

Author(s):

Li Qicheng ◽

Yuan Shupeng ◽

Zheng Xinjuan

Keyword(s):

Gulf Of Alaska ◽

Fault Model ◽

Finite Fault ◽

Finite Fault Model ◽

Alaska Earthquake

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The first month of the 2016 central Italy seismic sequence: fast determination of time domain moment tensors and finite fault model analysis of the ML 5.4 aftershock

Annals of Geophysics ◽

10.4401/ag-7246 ◽

2016 ◽

Vol 59 ◽

Author(s):

Laura Scognamiglio ◽

Elisa Tinti ◽

Matteo Quintiliani

Keyword(s):

Time Domain ◽

Moment Tensor ◽

Central Italy ◽

Model Analysis ◽

Fault Model ◽

Normal Faults ◽

Seismic Sequence ◽

Moment Tensors ◽

Finite Fault ◽

Finite Fault Model

We present the revised Time Domain Moment Tensor (TDMT) catalogue for earthquakes with M_L larger than 3.6 of the first month of the ongoing Amatrice seismic sequence (August 24th - September 25th). Most of the retrieved focal mechanisms show NNW–SSE striking normal faults in agreement with the main NE-SW extensional deformation of Central Apennines. We also report a preliminary finite fault model analysis performed on the larger aftershock of this period of the sequence (M_w 5.4) and discuss the obtained results in the framework of aftershocks distribution.

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Comparative study of the 3D tsunami simulations performed with the use of different approaches to the reconstruction of the bottom movement

10.5194/egusphere-egu21-14950 ◽

2021 ◽

Author(s):

Kirill A. Sementsov ◽

Sergey V. Kolesov ◽

Anna V. Bolshakova ◽

Mikhail A. Nosov

Keyword(s):

Input Data ◽

Fault Model ◽

Earthquake Source ◽

Data Type ◽

Ocean Bottom ◽

Source Type ◽

Finite Fault ◽

Finite Fault Model ◽

Type 3

Information on the earthquake source mechanism (Centroid Moment Tensor) becomes publicly available in a few minutes after the earthquake (for example, https://earthquake.usgs.gov/earthquakes or http://geofon.gfz-potsdam.de/eqinfo). Using this information, we can calculate the ocean bottom displacement in the earthquake area [Leonard, 2010; Okada, 1985] and then use this displacement as an input data for hydrodynamic simulation of the tsunami waves. Let us call this type of input data - Type 1. Somewhat later (and sometimes much later), than CMT, more detailed information on the rupture fault structure (Finite Fault Model) becomes available. According to Finite Fault Model, the rupture fault in the earthquake source consists of a certain number of segments characterized by their dip and strike angles. Each segment consists of a finite number of rectangular subfaults, for each of which a displacement vector, an activation time and a rise time are specified. By applying Okada's formulas to each subfault and using the principle of superposition, we can calculate the ocean bottom displacement in the earthquake area and also use it as an input data for tsunami simulations. Let us call this type of input data - Type 2. However, based on the Finite Fault Model, we are able to create a third type of input data (Type 3). To do this, it is necessary to take into account the displacement start time (subfault activation time) and the displacement duration (subfault rise time) of each subfault and consider the dynamics of the rupture process. In this case, we will be able to reconstruct not only the coseismic bottom displacement in the earthquake source (Type 2), but also describe the dynamics of the coseismic bottom displacement formation in the tsunami source (Type 3).&#160;This paper compares the tsunami simulation results performed with the of different types of input data (Type 1, Type 2 and Type 3). We performed calculations for a number of large earthquakes at the beginning of the 21st century. We took all the earthquake source information from the USGS catalog (https://earthquake.usgs.gov/earthquakes). The bottom deformations of all three types were calculated using the ffaultdisp code (http://ocean.phys.msu.ru/projects/ffaultdisp/). Tsunami modeling was carried out using a combined 2D / 3D CPTM model [Nosov, Kolesov, 2019; Sementsov et al., 2019]. The simulation results are compared with each other as well as with the DART ocean bottom observatories records.&#160;The study was supported by Russian Foundation for Basic Research (projects 20-35-70038, 19-05-00351, 20-07-01098).&#160;

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Speeding up and boosting tsunami warning in Chile

10.5194/nhess-2019-9 ◽

2019 ◽

Author(s):

Mauricio Fuentes ◽

Sebastian Arriola ◽

Sebastian Riquelme ◽

Bertrand Delouis

Keyword(s):

Real Time ◽

Near Field ◽

Linear Method ◽

Seismic Energy ◽

Fault Model ◽

Tsunami Forecast ◽

Finite Fault ◽

Run Up ◽

Finite Fault Model ◽

Chile Tsunami

Abstract. Chile host a great tsunamigenic potential along its coast, even with the large earthquakes occurred during the last decade, there is still a large amount of seismic energy to release. This permanent feature and the fact that the distance between the trench and the coast is just 100 km creates a difficult environment to do real time tsunami forecast. In Chile tsunami warnings are based on reports of the seismic events (hypocenter and magnitude) and a database of precomputed tsunami scenarios. However, because yet there is no answer to image the finite fault model within first minutes (before the first tsunami wave arrival), the precomputed scenarios consider uniform slip distributions. Here, we propose a scheme of processes to fill the gaps in-between blind zones due to waiting of demanding computational stages. The linear shallow water equations are solved to obtain a rapid estimation of the run-up distribution in the near field. Our results show that this linear method captures most of the complexity of the run-up heights in terms of shape and amplitude when compared with a fully non-linear tsunami code. Also, the run-up distribution is obtained in quasi real-time as soon as the seismic finite fault model is produced.

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