# Modeling the Impact of the Viscoelastic Layer Thickness and the Frictional Strength to the Lithosphere Deformation in a Strike-Slip Fault: Insight to the Seismicity Pattern along the Great Sumatran Fault

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## Abstract

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## 1. Introduction

## 2. Methods

#### 2.1. Model Building

#### 2.2. Deformation Simulation

## 3. Results

#### 3.1. Strain Build-Up Model

#### 3.2. Strain Release Model

## 4. Discussion

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 2.**Numerical mesh of the finite element model using three different scenarios: (

**a**) an equal thickness of 3 km for the elastic upper crust (

**upper**mesh layer) and the viscoelastic lower crust and upper mantle (

**lower**mesh layer) as scenario one; (

**b**) a thinner elastic upper crust layer (2 km) than the viscoelastic layer (4 km) as scenario two; and (

**c**) a thicker elastic upper crust layer (4 km) than the viscoelastic layer (2 km) as scenario three.

**Figure 3.**Displacement model for scenario one: (

**a**) the strain buildup model at time simulation of 250 years using friction coefficient 0.6 and cohesion 2 MPa; (

**b**) the strain release model using slip 7.575 m.

**Figure 4.**Displacement with distance from the fault of strain buildup model at year 250 based on different friction coefficients and cohesion values in three scenarios: (

**a**) scenario one, (

**b**) scenario two, and (

**c**) scenario three.

**Figure 5.**Slip magnitude of strain buildup model based on different friction coefficients and cohesion values in three scenarios: (

**a**) scenario one, (

**b**) scenario two, and (

**c**) scenario three.

**Figure 6.**Differential stress at the center of each layer of strain buildup model based on (

**a**) different friction coefficients and (

**b**) different cohesion levels.

**Figure 7.**Differential stress at the boundary of each layer of strain buildup model based on (

**a**) different friction coefficient and (

**b**) different cohesion.

**Figure 8.**Displacement with the distance of strain release model with slip of 7.575 m in three scenarios (

**left**) at 505 years and (

**right**) at 750 years for (

**a**) scenario one, (

**b**) scenario two, and (

**c**) scenario three.

**Figure 9.**Differential stress of strain release model on the boundary of each layer with varied slip magnitudes (3 m, 4.5 m, 6 m, and 7.575 m).

**Figure 10.**The variation in crustal depth along GSF based on CRUST1.0 model and the M ≥ 7.0 earthquake history since 189 [20].

Material Block | P-Wave Velocity (m/s) | S-Wave Velocity (m/s) | Density (kg/m^{3}) | Viscosity (Pa s) |
---|---|---|---|---|

Upper crust (elastic) | 6625 | 4064 | 2700 | 0 |

Lower crust & upper mantle (viscoelastic Maxwell) | 7230 | 4470 | 2900 | 7.10046 × 10^{19} |

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**MDPI and ACS Style**

Bening, M.A.; Sahara, D.P.; Triyoso, W.; Kusumawati, D. Modeling the Impact of the Viscoelastic Layer Thickness and the Frictional Strength to the Lithosphere Deformation in a Strike-Slip Fault: Insight to the Seismicity Pattern along the Great Sumatran Fault. *GeoHazards* **2022**, *3*, 452-464.
https://doi.org/10.3390/geohazards3040023

**AMA Style**

Bening MA, Sahara DP, Triyoso W, Kusumawati D. Modeling the Impact of the Viscoelastic Layer Thickness and the Frictional Strength to the Lithosphere Deformation in a Strike-Slip Fault: Insight to the Seismicity Pattern along the Great Sumatran Fault. *GeoHazards*. 2022; 3(4):452-464.
https://doi.org/10.3390/geohazards3040023

**Chicago/Turabian Style**

Bening, Maulidia A., David P. Sahara, Wahyu Triyoso, and Dian Kusumawati. 2022. "Modeling the Impact of the Viscoelastic Layer Thickness and the Frictional Strength to the Lithosphere Deformation in a Strike-Slip Fault: Insight to the Seismicity Pattern along the Great Sumatran Fault" *GeoHazards* 3, no. 4: 452-464.
https://doi.org/10.3390/geohazards3040023