3D Seismic Model Research Articles

3D seismic forward modeling from the multiphysical inversion at the Ketzin CO2 storage site

3D seismic forward modeling from the multiphysical inversion at the Ketzin CO2 storage site

Evidence for faulting and fluid-driven earthquake processes from seismic attenuation variations beneath metropolitan Los Angeles

Seismicity in the Los Angeles metropolitan area has been primarily attributed to the regional stress loading. Below the urban areas, earthquake sequences have occurred over time showing migration off the faults and providing evidence that secondary processes may be involved in their evolution. Combining high-frequency seismic attenuation with other geophysical observations is a powerful tool for understanding which Earth properties distinguish regions with ongoing seismicity. We develop the first high-resolution 3D seismic attenuation models across the region east of downtown Los Angeles using 5,600 three-component seismograms from local earthquakes recorded by a dense seismic array. We present frequency-dependent peak delay and coda-attenuation tomography as proxies for seismic scattering and absorption, respectively. The scattering models show high sensitivity to the seismicity along some of the major faults, such as the Cucamonga fault and the San Jacinto fault zone, while a channel of low scattering in the basement extends from near the San Andreas fault westward. In the vicinity of the Fontana seismic sequence, high absorption, low scattering, and seismicity migration across a fault network suggest fluid-driven processes. Our attenuation and fault network imaging characterize near-fault zones and rock-fluid properties beneath the study area for future improvements in seismic hazard evaluation.

Improved Earthquake Source Parameters with 3D Wavespeed Models in California and Nevada

Abstract Seismic tomography harnesses earthquake data to explore the inaccessible structure of the Earth. Adjoint waveform tomography (AWT), a method of seismic tomography, updates the tomographic model by optimizing the fit between observed earthquake data and synthetic waveforms. The synthetic data are calculated by solving the wave equation through a given 3D model. An important requirement to calculating synthetics is the source information (location, centroid time, depth, and moment tensor). Errors in source information affect the quality of the synthetics produced, which in turn can limit how structure can be inferred in the AWT workflow. To test the effect of updating source information, we used MTTime (Chiang, 2020), a time-domain full-waveform moment tensor inversion code, to calculate the moment tensors and depths of 118 earthquakes that occurred in California and Nevada over a 20-yr period. We calculated 3D Green’s functions using a 3D seismic wavespeed model of California and Nevada (Doody et al., 2023b). We show that the inverted solutions provide better waveform fits than the Global Centroid Moment Tensor catalog and increase usable, well-correlated data by up to 7%. Therefore, we argue that recalculating source parameters should be considered in AWT workflows, particularly for smaller magnitude events (Mw<5.0).

Seismic Hazard Assessment in the Southeastern Korean Peninsula for Large Earthquakes in Northern Kyushu, Japan: A 3D Numerical Simulation of Pseudodynamic Rupture Scenarios

Abstract Active fault segments in the Northern Kyushu area are of concern in seismic hazard analysis of the southeastern Korean Peninsula (KP) due to their proximity. In this study, we numerically simulate the peak ground motions at the southeastern KP for Mw 6.7–7.1 earthquake scenarios at five major active fault segments located in northern Kyushu: Kego SouthEastern, Nishiyama OshimaOki, Nishiyama Nishiyama, Kikugawa Central, and Kikugawa Northern fault segments. We conducted fully 3D seismic-wave propagation simulations integrating 3D seismic velocity model and earthquake scenarios generated through pseudodynamic rupture modeling. After applying the region-specific attenuation value, the predicted peak ground velocities (PGVs) ranged from 0.18 cm/s (modified Mercalli intensity [MMI] III) to 26.76 cm/s (MMI VIII), depending on the earthquake scenarios. The PGV distributions were influenced by several factors, such as crustal velocity anomalies, rupture directivity, and the distribution of source parameters on the fault plane. Despite the fixed fault geometries, magnitudes, and hypocenters, significant variations in peak ground-motion distributions were simulated due to differences in the source statistics. The estimated probability density distributions of PGV indicated a significant likelihood of peak ground motions surpassing 20 cm/s in the Yeongnam Province. Furthermore, we identify a linear relationship between the average PGV values and standard deviation across 20 scenarios for each fault segment, to quantify the uncertainty in the PGV distributions.

On cost-efficient parallel iterative solvers for 3D frequency-domain seismic multisource viscoelastic anisotropic wave modeling

Solving large sparse linear systems in 3D frequency-domain seismic wave modeling, especially in viscoelastic anisotropic media, poses significant challenges due to the increasing number of discrete moduli and nonzero elements in the linear system matrix. The computational load surpasses that of acoustic or viscoacoustic media, making it even more challenging when dealing with multisource problems. Popular scientific tools for solving a linear system, such as multifrontal massively parallel sparse direct solver (MUMPS), structured matrix package (STRUMPACK), and portable extensible toolkit for scientific computation (PETSc), can be used, but their applicability to our specific problem has not been comprehensively evaluated. Our study aims to tackle the challenges in solving large, sparse, complex-valued symmetric linear systems with multiple right-hand side vectors for 3D frequency-domain seismic wave modeling. We have adopted the preconditioned conjugate gradient iterative algorithms as the foundation for our research, introducing two highly cost-effective parallel iterative solvers: the parallel symmetric successive overrelaxation conjugate gradient (P-SSORCG) and the parallel incomplete Cholesky conjugate gradient (P-ICCG). These novel solvers are subjected to a comprehensive comparative analysis against well-established scientific tools, such as MUMPS, STRUMPACK, and PETSc, in the context of 3D frequency-domain seismic wave modeling. We show their promising performances in a practical 3D SEG/EAGE overthrust model and demonstrate that the grouped P-SSORCG offers an efficient alternative to parallel direct solvers, particularly in situations wherein computational resources are limited.

Structural Characterization of the Taltal Segment in Northern Chile Between 22°S and 26°S Using Local Earthquake Tomography

AbstractRecordings of earthquakes by a temporary deployment of 84 short period seismometers in northern Chile were used to derive regional 3D seismic velocity models for the Taltal segment. We used the Regressive ESTimator (REST) package for event detection and automatic onset estimation of P‐ and S‐wave arrival times to create an earthquake catalog with 23,985 hypocenters. We followed standard acceptability criteria (i.e., azimuthal gap and residual cutoff) to create a high‐quality data set and inverted for 3D Vp, Vs and Vp/Vs models using local earthquake tomography. Plots of hypocenters from the catalog, comprising 16,349 earthquakes, reveal active structures in the upper crust, dip changes along the slab and fracturing within the oceanic crust. Moreover, the wavespeed models illuminate anomalies in both the Nazca and South American plates that correlate with the observed seismicity distribution, including variations from low (1.75) to high (>1.80) Vp/Vs near the Atacama fault system on the coastline and the Domeyko Fault System in the forearc. The seismic velocity models also provide evidence for fluid circulation caused by the subducting Taltal ridge on the coast and partial melting feeding a volcanic complex close to the Andes. Finally, the observed low Vp/Vs ratios (∼1.75) are associated with copper mining operations in the area, suggesting that this kind of imaging can be used to characterize the distribution of potential ore deposits in the area.

METHODS FOR 3D INVERSION OF GRAVITY DATA IN INDENTIFYING TECTONIC FACTORS CONTROLLING HYDROCARBON ACCUMULATIONS IN THE EL ZEIT BASIN AREA, SOUTHWESTERN GULF OF SUEZ, EGYPT

The Gebel EL-Zeit area in the southwestern Gulf of Suez, Egypt, is an area with a significant hydrocarbon potential in sedimentary basins, so that the three-stage inversion method was proposed for the Bouguer anomalies observed therein. Salt diapirs obscured the deep structure of the main central El-Zeit basin; hence, this method was implemented to overcome challenges in 3D seismic modeling. Our study included direct and inverse parameterization sequences that involved analyzing the inputs and outputs within trial-and-error initiations and inverse estimations to assess whether and how much the constraining parameters used in the calculations could achieve the intended aim. Data reduction, filtering, optimization, and constraint assumptions were used to determine the minimal set of density model parameters needed to set limits on the acceptable range of density contrasts that are required to study the basement depths, swells, troughs, faulting/folding and intra-sedimentary structures, and for direct modeling aimed at creating a simple model to save time. The thirteen constrained wells with a total depth ranging from shallow to deep were not involved in direct modeling but provided quality control over the graphical display of the inverse results for the entire study area. Moreover, many parameter constraints were inverted to regulate the way the calculated data are related to the model’s solution that allowed us to determine which inversion trial provided the best parameterization sequence and, therefore, yielded the most appropriate solution for the depth-density model which is approximating reality with a minimal computation error in the study area.

3D Wave Propagation Simulations of Mw 6.5+ Earthquakes on the Tacoma Fault, Washington State, Considering the Effects of Topography, a Geotechnical Gradient, and a Fault Damage Zone

ABSTRACT We simulate shaking in Tacoma, Washington, and surrounding areas from Mw 6.5 and 7.0 earthquakes on the Tacoma fault. Ground motions are directly modeled up to 2.5 Hz using kinematic, finite-fault sources; a 3D seismic velocity model considering regional geology; and a model mesh with 30 m sampling at the ground surface. In addition, we explore how adjustments to the seismic velocity model affect predicted shaking over a range of periods. These adjustments include the addition of a region-specific geotechnical gradient, surface topography, and a fault damage zone. We find that the simulated shaking tends to be near estimates from empirical ground-motion models (GMMs). However, long-period (T = 5.0 s) shaking within the Tacoma basin is typically underpredicted by the GMMs. The fit between simulated and GMM-derived short-period (T = 0.5 s) shaking is significantly improved with the addition of the geotechnical gradient. From comparing different Mw 6.5 earthquake scenarios, we also find that the response of the Tacoma basin is sensitive to the azimuth of incoming seismic waves. In adding surface topography to the simulation, we find that average ground motion is similar to that produced from the nontopography model. However, shaking is often amplified at topographic highs and deamplified at topographic lows, and the wavefield undergoes extensive scattering. Adding a fault damage zone has the effect of amplifying short-period shaking adjacent to the fault, while reducing far-field shaking. Intermediate-period shaking is amplified within the Tacoma basin, likely due to enhanced surface-wave generation attributable to the fault damage zone waveguide. When applied in the same model, the topography and fault damage zone adjustments often enhance or reduce the effects of one another, adding further complexity to the wavefield. These results emphasize the importance of improving near-surface velocity model resolution as waveform simulations progress toward higher frequencies.

3D seismic tomography models of the Baikal Rift zone and surrounding areas based on regional seismological data

3D seismic tomography models of the Baikal Rift zone and surrounding areas based on regional seismological data

Geophysical Modeling and Its Contribution on the Reservoir Characterization of Al Baraka in El Gallaba Plain, South Egypt

Summary The early Cretaceous formations in recent years are considered significant potential hydrocarbon-bearing rocks in many rift basins such as Komombo, south Egypt. Therefore, this study is focused on the critical analysis and interpretation of well logging together with seismic reflection data on the Al Baraka petroliferous reservoir in the Komombo subbasin. The interpretation of these data was used to construct the first 3D geophysical models in this area which were subsequently interpreted in terms of their potential to be hydrocarbon-bearing or not. The 3D petrophysical models were deduced to illustrate the spatial distribution and propagation of the petrophysical properties (laterally and vertically) within the reservoir. Additionally, 3D seismic models were prepared to get a comprehensive, in-depth picture of how the productive hydrocarbon reservoir zones are structurally controlled in different depths. So, these models are crucial for explaining reservoir characteristics and providing supported geological reservoir models for precise reservoir performance prediction. This study aims to differentiate and determine hydrocarbon potential zones in terms of the petroleum system. The results of these progressive analyses showed that only two zones (C and D) in the Six Hills Formation are considered the most productive zones because they have a large thickness of sand bodies, low-water saturation values, high porosity, and high permeability. These zones are located in the northeastern and central parts of the studied area, which represent the depocenter of the subbasin. This evidence supported and confirmed the presence of petroleum accumulations in certain zones within the Six Hills Formation. Therefore, this work can give and encourage experts with adequate knowledge to understand the development of the rift basins in Komombo and other basins in middle and south Egypt.

Relationship Between Crustal Structure and Plate Convergence Around the Izu Collision Zone in Central Japan

AbstractWe conducted a receiver function (RF) analysis to understand the convergence process in and around the Izu collision zone. We calculated the P‐ and S‐wave RFs and converted them to depth using a three‐dimensional (3D) regional tomography model and regionally estimated near‐surface structure. We detected the Moho of the Philippine Sea Plate and determined its 3D geometry in and around the collision zone. In addition, we considered the 3D seismic velocity model, which was previously determined using seismic tomography, and we complemented a part of the Moho that we did not detect using the RFs. Based on the geometry of the upper surface of the Philippine Sea Plate determined in previous studies, the crust is >35 km thick beneath the Izu Peninsula and collision zone and becomes thinner (<20 km) moving east of the collision zone. Thus, the thick crust along the Izu‐Bonin arc collides, and the thin forearc crust subducts. A stable slip surface was previously assumed to exist at a 15–20 km depth beneath the Izu Peninsula and the collision zone. This study indicates that the surface should exist within the crust of the Philippine Sea Plate.

Reconciling the onshore/offshore stratigraphy of the Canning Basin and implications for petroleum prospectivity

The Canning Basin is a prospective hydrocarbon frontier basin and is unusual for having limited offshore seismic and well data in comparison with its onshore extent. In this study, seismic mapping was conducted to better resolve the continuity of 13 key stratigraphic units from onshore to offshore to delineate prospective offshore hydrocarbon-bearing units, and better understand the distribution of mafic igneous units that can compartmentalise migration pathways and influence heat flow. The offshore Canning Basin strata are poorly constrained in six wells with limited seismic coverage; hence data availability was bolstered by integrating data from the onshore portion of the basin and adjacent basins into a single 3D seismic stratigraphic model. This model integrates over 10 000 km of historical 2D seismic data and 23 exploration wells to allow mapping of key stratal surfaces. Mapped seismic horizons were used to construct isochores and regional cross-sections. Seven of the 13 units were mapped offshore for the first time, revealing that the onshore and offshore stratigraphy are similar, albeit with some minor differences, and mafic igneous units are more interconnected than previously documented whereby they may constitute a mafic magmatic province. These basin-scale maps provide a framework for future research and resource exploration in the Canning Basin. To better understand the basin’s geological evolution, tectonic history and petroleum prospectivity, additional well data are needed in the offshore Canning Basin where Ordovician strata have yet to be sampled.

The effect of fluid flow in the longitudinal fracture along a borehole axis on Stoneley wave propagation

The characterization of fractures is essential to increase the production of hydrocarbon and geothermal resources. In this study, we investigate the effect of the fluid flow in the longitudinal fracture along a borehole on the dispersion and attenuation behavior of Stoneley waves using numerical experiments. In general, incorporating a fracture with the aperture of several tens to hundreds of micrometers into 3D seismic modeling is challenging with high calculational costs. We develop a novel numerical scheme that includes a 2D fluid flow simulation embedded into a 3D wave propagation modeling to address this problem. We devise an approach for capturing the effects of the fluid flow in the fractures of arbitrary aperture widths, which could be much thinner than the grid spacing of a 3D wave propagation simulation. A comparison of the numerical results from our scheme with the analytical solution indicates good agreement, supporting the method’s validity. This developed scheme is applied to the coupled simulation between the Stoneley wave propagation along the borehole axis and induced fluid flow inside a longitudinal fracture with different fracture apertures, fluid viscosity, and dynamic hydraulic conductivity. The modified matrix pencil algorithm applied to the recorded waveforms estimates the dispersion and attenuation of the Stoneley mode. The numerical results reveal the effect of the fracture aperture and fluid viscosity on the dispersion and attenuation behavior of the Stoneley waves. Based on the results, we demonstrate our scheme is an innovative method for estimating the aperture of the fracture and viscosity of the fluid by analyzing the dispersion and attenuation properties of the Stoneley waves.

All-in-one proxy to replace 4D seismic forward modeling with machine learning algorithms

Time-lapse seismic data provides valuable information to assist reservoir monitoring, model-based reservoir management, and development activities. 4D seismic information can be used quantitatively to estimate saturation-pressure changes or update reservoir simulation models through a data assimilation process, which traditionally requires a 4D seismic forward model that includes two steps: (1) petro-elastic model to relate rock and fluid properties to elastic attributes and (2) seismic model to depict wave propagation in the reservoir. The traditional forward model brings some complications in quantitative applications, such as time-lapse seismic history matching. Its multidisciplinary nature is a significant bottleneck to update simulation models, once observed 4D seismic data is used with production data in the assimilation process. Furthermore, it is time-consuming, especially in three-dimensional simulation models within data assimilation with several iterations. Here, the traditional forward model needs to be run hundreds or even thousands of times. Aside from being time-consuming, it requires substantial computer memory for complex geology, where more sophisticated seismic models are needed. In 4D seismic quantitative applications, the timely use of the information and its full benefits fade away due to the computational cost and time of the 4D seismic forward model. This research proposes a proxy (we call it, S4D-Proxy) to replace the traditional approach. The S4D-Proxy leverages machine learning models to detect hidden patterns and learn relations between input features (e.g., porosity and saturation-pressure changes) and the target (time-lapse difference of seismic amplitude). Training data are prepared and fed to the machine learning algorithms to relate the inputs and the desired output. The performances of the machine learning models are evaluated based on a numerical measure (coefficient of determination) and visual comparison of the results with the traditional forward model. Our results show that the average coefficient of determination for the test dataset is in an acceptable range. Moreover, the visual comparison of the proxy predictions with those from the traditional approach shows high similarity. Most hardening and softening 4D signals are reproduced with the proxy models. The main advantage of our approach is that it lowers the computational cost and time. The application of the proxy in data assimilation process could offer a significant speed advantage with faster 4D seismic forward modeling for data assimilation iterations. Unlike the traditional forward model, which is one step (petro-elastic model) then another (seismic model), our approach performs the forward modeling at once (all-in-one proxy model). It also offers an alternative 4D seismic forward model for time-lapse seismic feasibility study. All these advantages make the S4D-Proxy valuable and practical in permanent reservoir monitoring (PRM), where the reduced turnaround time in the forward model indicates the timely use of the 4D seismic information.

Integrated Prospectivity Evaluation of XYZ Field Coastal-Swamp Depobelt Niger-Delta Basin Nigeria

Five studies were conducted on the “XYZ” field to understand its reservoir properties, structural settings, and hydrocarbon-in-place. Petrophysical parameters were calculated using appropriate equations and wireline logs. 3D seismic fault models were created. A stacking pattern of the reservoir sand bodies was interpreted from a gamma-ray motif. The reservoir surface area was deduced using hydrocarbon indicators and seismic amplitude change. A seismic inline section corresponding with the reservoir zone was used for the seismic facie studies. Reservoir R1 has net-thickness of 111.71m and 117.09m, N/G ratio of 76% and 85%, effective porosity of 25% and 28%, hydrocarbon saturation of 44% and 40%, permeability of 14md and 16md, and Formation factor of 156.32 and 13.77 in well “XYZ-03” and “XYZ-05” respectively.Three-ways and two-ways fault-dependent closures with an anticlinal stratigraphic closure were delineated towards the western and middle parts of the field. Reservoir R1 generally shows an aggrading stacking pattern. R1 associated with wells "XYZ-03" and “XYZ-05” has hydrocarbon volume of 272,293.40m3 (1,712,674 bbl) and 193, 502.93m3 (1,217,097 bbl) respectively. Seismic facies showed continuous reservoir sand bodies. The field is endowed with moderate to good multiple reservoirs, and effective fault and stratigraphic closures, which support economically considerable hydrocarbon volume.

Developing a Consistent Travel-Time Framework for Comparing Three-Dimensional Velocity Models for Seismic Location Accuracy

Location algorithms have historically relied on simple, one-dimensional (1D) velocity models for fast seismic event locations. 1D models are generally used as travel-time lookup tables, one for each seismic phase, with travel-times pre-calculated for event distance and depth. These travel-time lookup tables are extremely fast to use and this fast computational speed makes them the preferred type of velocity model for operational needs. Higher-dimensional (i.e., three-dimensional—3D) seismic velocity models are becoming readily available and provide more accurate event locations over 1D models. The computational requirements of these 3D models tend to make their operational use prohibitive. Additionally, comparing location accuracy for 3D seismic velocity models tends to be problematic, as each model is determined using different ray-tracing algorithms. Attempting to use a different algorithm than the one used to develop a model usually results in poor travel-time prediction. We demonstrate and test a framework to create first-P and first-S 3D travel-time correction surfaces using an open-source framework (PCalc + GeoTess, https://www.sandia.gov/salsa3d/software/geotess) that easily stores 3D travel-time and uncertainty data. This framework produces fast travel-time and uncertainty predictions and overcomes the ray-tracing algorithm hurdle because the lookup tables can be generated using the exact ray-tracing algorithm that is preferred for a model.

New Insights on Subsurface Geology and the San Andreas Fault at Loma Prieta, Central California

ABSTRACT The 1989 Mw 6.9 Loma Prieta earthquake is the first major event to occur along the San Andreas fault (SAF) zone in central California since the 1906 M 7.9 San Francisco earthquake. Given the complexity of this event, uncertainty has persisted as to whether this earthquake ruptured the SAF itself or a secondary fault. Recent work on the SAF in the Coachella Valley in southern California has revealed similar complexity, arising from a nonplanar, nonvertical fault geometry, and has led us to reexamine the Loma Prieta event. We have compiled data sets and data analyses in the vicinity of the Loma Prieta earthquake, including the 3D seismic velocity model and aftershock relocations of Lin and Thurber (2012), potential field data collected by the U.S. Geological Survey following the earthquake, and seismic refraction and reflection data from the 1991 profile of Catchings et al. (2004). The velocity model and aftershock relocations of Lin and Thurber (2012) reveal a geometry for the SAF that appears similar to that in the Coachella Valley (although rotated 180°): at Loma Prieta the fault dips steeply near the surface and curves with depth to join the moderately southwest-dipping main rupture below 6 km depth, itself also nonplanar. The SAF is a clear velocity boundary, with higher velocities on the northeast, attributable to Mesozoic accretionary and other rocks, and lower velocities on the southwest, attributable to Cenozoic sedimentary and volcanic rocks of the La Honda block. Rocks of the La Honda block have been offset right-laterally hundreds of kilometers from similar rocks in the southern San Joaquin Valley and vicinity, providing evidence that the curved northeast fault boundary of this block is the plate boundary. Thus, we interpret that the Loma Prieta earthquake occurred on the SAF and not on a secondary fault.

An integrated source rock potential, sequence stratigraphy, and petroleum geology of (Agbada-Akata) sediment succession, Niger delta: application of well logs aided by 3D seismic and basin modeling

We investigated the source rock potential, sequence stratigraphy, and characterized hydrocarbon reservoirs at Otumara field, Niger delta, using integrated 3D seismic, wireline log analysis, and basin modeling. The burial history and thermal maturity were modeled, the reservoirs were delineated, and the petrophysical parameters were also estimated from the wireline logs. The Passey “ΔLog R” method for estimating the preliminary evaluations of the total organic carbon (TOC) from integrating sonic, neutron, and density with resistivity has been used. The results indicate that the primary source rock of hydrocarbons is the Upper Akata Formation, despite a higher TOC percentage in the Agbada Formation. Based on sequence stratigraphy analysis, TA4, TB1, TB2, and TB3 second-order supercycles were obtained in the studied well TD46. The results also revealed that the field has two large net pays with high-quality reservoir facies: a deltaic slope fan at the upper shoreface and a river mouth sandbar at the lower shoreface. Furthermore, the reservoirs were faulted by a series of growing faults that faulted the basin slope. The reservoir facies are characterized by an average of 18% porosity, 1200 mD permeability, 16% volume of shale, and high hydrocarbon saturation of about 85%. Finally, the petroleum system elements have been defined for improved hydrocarbon exploration. In the absence of complete or partial core samples, this case study emphasizes the importance of using wireline logs to estimate organic richness and investigate sequence stratigraphy in clastic sediments.

Double Seismic Zones along the Eastern Aleutian-Alaska Subduction Zone Revealed by a High-Precision Earthquake Relocation Catalog

Abstract The Eastern Aleutian-Alaska Subduction Zone (EAASZ) manifests significant along-strike variations in structure and geometry. The limited spatial resolution in intermediate-depth earthquake locations precludes investigation of small-scale variations in seismic characteristics. In this study, we use an existing 3D seismic velocity model and waveform cross-correlation data to relocate the earthquakes in 2016 near the EAASZ. Our improved absolute and relative earthquake locations reveal complex spatial characteristics of double seismic zones (DSZs). There are significant variations in location, depth, layer separation, and length of the DSZs along the EAASZ. We also observe nonuniform layer separations along the slope of the subducting slab that may imply either rheological or crustal thickness variations. In addition, our results suggest a triple seismic zone (TSZ) beneath Kenai. The interplay among different factors, including dehydration of metamorphic facies, intraslab stress, preexisting structures, and abrupt changes in slab geometry, may explain the observed variations in seismogenesis of the DSZs and TSZs. The comparison of our relocated seismicity with the thermal model for the slab beneath Cook Inlet shows that the intermediate-depth earthquakes occur between 500°C and 900°C isotherms. The 2016 Mw 7.1 Iniskin earthquake and its aftershocks are located at ∼800°C–900°C. The intricate small-scale variations in different characteristics of the DSZs and intermediate-depth seismicity and their correlations with major geometrical and physical controls can provide insight into what governs the seismogenesis of subduction-induced earthquakes.

3D outcrop geologic modeling and seismic forward modeling of mound-beach complexes

3D outcrop geologic modeling and seismic forward modeling of mound-beach complexes