the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 20 Aug 2026
EFEL 1.0: An integrated set of components for Landlab to simulate landscape evolution from fault creep, earthquakes, and coseismic landslides
Abstract. I present a suite of new numerical model components for use with Landlab, collectively the Elastic Fault, Earthquake, and Landslide (EFEL) model that enable users to simulate surface deformation related to both interseismic creep and seismogenic events on faults of variable geometry and include the effects of coseismic landslides. The surface deformation from either interseismic creep or individual earthquakes are simulated as discrete, rectangular dislocations within an isotropic, linear elastic half-space. The location of coseismic landslides are determined through the implementation of several different empirical ground motion prediction equations coupled with a Newmark style sliding-block analysis. Used together, the components allow for the generation of either dipping or vertical faults of variable geometries with independent kinematics, the generation of earthquake catalogs with varying levels of complexity for simulating surface deformation, and coupling these with existing Landlab libraries for simulating surface processes. I present a variety of examples using these components, including landscape evolution above both an aseismic and seismogenic shallow dipping thrust fault, considered without and with coseismic landslides, landscape evolution above both aseismic and seismogenic simple high angle normal faults and listric normal faults, and landscape evolution along both aseismic and seismogneic strike-slip faults with or without a restraining bend. These components fill an important gap within existing Landlab libraries, and landscape evolution models more broadly, providing a prepackaged method for users to simulate complicated deformation of single-fault systems in concert with surface processes.
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Status: open (until 15 Oct 2026)
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CEC1: 'Comment on egusphere-2026-4659 - No compliance with the policy of the journal', Juan Antonio Añel, 22 Sep 2026
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AC1: 'Reply on CEC1', Adam Forte, 22 Sep 2026
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I have modified the original Zenodo repository that houses the main code to now include static versions of both Landlab and okada4py. Here is the DOI of the new version of this repository: https://doi.org/10.5281/zenodo.22901369. Does this satisfy the requirements?
Citation: https://doi.org/10.5194/egusphere-2026-4659-AC1 -
CEC2: 'Reply on AC1', Juan Antonio Añel, 22 Sep 2026
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Dear authors,
Thanks for addressing this issue so quickly. I have checked the repositories and we can consider now the current version of your manuscript in compliance with the code policy of the journal.
Juan A. Añel
Geosci. Model Dev. Executive Editor
Citation: https://doi.org/10.5194/egusphere-2026-4659-CEC2
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CEC2: 'Reply on AC1', Juan Antonio Añel, 22 Sep 2026
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AC1: 'Reply on CEC1', Adam Forte, 22 Sep 2026
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RC1: 'Comment on egusphere-2026-4659', Anonymous Referee #1, 23 Sep 2026
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Summary:
In this work, Forte presents three new components for the modular, open-source Landlab landscape evolution model framework that simulate faults, earthquakes, and coseismic landslides and implements them with a suite of example Landlab landscape evolution models. These components are a long-awaited and welcome update to the Landlab model ecosystem. However, the writing can be improved and there are a few unclear aspects about how the model components work.
General Comments:
- Constant Interseismic Creep: The idea behind this is not fully described in the paper, nor is the implementation. Is it meant to simulate a lower crustal shear zone that drives upper crust fault slip? If so, the slip rate of the overlying upper crustal faults shouldn’t need to be set. If not, what is it supposed to represent? Can it be set to zero? How do slip rates set on the fault components affect the interseismic creep rate and vice versa? Does the interseismic creep rate have to equal the amount of strain released by an earthquake sequence or how far apart can they get before the earthquake sequence “catches up” to the amount of interseismic creep during a simulation?
- Elastic Rebound: Perhaps related to comment #1, how is the rebound portion of the elastic earthquake cycle handled? Is that what the interseismic creep rate is supposed to do? And if so, how is it implemented? For example, the surface deformation associated with interseismic creep for a subduction zone is very different than for a strike-slip fault. None of the example models use a subduction zone fault. For the deformation to be Okada-style and elastic, the rebound also has to be implemented, and the rebound may have a big impact in landscape evolution for subduction zone regions and faults with dip slip. For example, we know from recent normal faulting earthquakes in the Basin and Range that the primary coseismic signal is basin subsidence, and range uplift primarily happens during the interseismic period (e.g., Thompson & Parsons, 2016, https://doi.org/10.1002/2015JB012240).
- Earthquake Scaling Relationships: Leonard (2014) is one of many earthquake scaling publications, and all earthquake scaling relationships have fairly large uncertainty bounds because they are based on inherently noisy, cloudy empirical data. For strike-slip faults, the Leonard 2014 relationship predicts longer rupture lengths than many other scaling relationships (see Figure 1 in Reitman et al., 2026, https://doi.org/10.1785/0220250257). It would be more useful to be able to select a range of scaling relationships and calculate an envelope of available rupture length, width, and slip so as not to overly constrain ruptures since in the real world they are constantly surprising us with their dimensions. At least, please add implementation of Wells & Coppersmith (1994, http://dx.doi.org/10.1785/BSSA0840040974) and Blaser et al., (2010, http://dx.doi.org/10.1785/0120100111) scaling relationships.
- Aftershocks: Two points here. First, it’s not clear that aftershocks make a measurable impact on landscape evolution because depending on the time step chosen, most aftershocks will be lumped with the main shock in terms of surface deformation and the appendix states that aftershocks that occur “a very long time after” the parent event are not included in landscape simulations (line 1129). Also, aftershocks commonly occur in the surrounding volume of the ruptured fault, which isn’t possible in the model setup (model limitations mean that aftershocks only occur on the input fault plane, correct?). It would be neat to see a test of the same model setup with and without aftershocks to compare the resultant landscape. Second, for the aftershock sequence, how is distance from the earthquake calculated? Is it based only on the hypocenter location, or is it based on the patch of the fault that ruptured? This is especially important because aftershocks often occur at the edge of the ruptured patch and are NOT uniformly or randomly distributed throughout a rupture patch.
- Ground Motions: For the GMPEs used in CoseismicLandslider, how is distance from the earthquake calculated? Is it based on hypocenter location or distance of the node to a ruptured patch on the fault (taking both vertical and horizontal distances into account)? Also for the GMPEs, it’s fine to make simplifying assumptions and choose particular GMPEs to implement, but standard practice for hazard purposes is to use multiple GMPEs and calculate a suite of possible PGA values. It would be useful if that were an option.
- Total Displacement: For all example simulations, please state the total displacement for the model run time. Please also show a graph of model run time vs displacement for each model. Much of the difference in topography for the simple thrust models, as seen in figure 7, may be due to differences in total uplift, but it isn’t possible to evaluate because total uplift values are not in the manuscript or Table D1.
- Subduction zone settings – It’s still a little unclear if these components can be used to simulate a semi-realistic subduction zone setting. Please address, either with an example model or in the setup and discussion.
- Writing & Grammar: The manuscript is long (25 figures!), with verbose writing that could be simplified. One example is omitting the frequently used meta-discourse, such as: “In the following section, I will…”, “It should be noted that…”, and “it should be emphasized that…”. Other words that add text without meaning and can be omitted are: “generally”, “largely”, “nominally”, and “effectively”. Slip rate is not hyphenated unless it is modifying another word. Additionally, there are a number of instances with incorrect subject-verb agreement for singular vs plural subjects, and some typos. Some are pointed out in line comments. Please read closely to correct grammar and condense and simplify the writing. I can’t believe I’m saying this, but AI could be useful to simplify the writing and make it more direct. See an example of (human) simplified writing at the end of this review. Figure comments contain suggestions for possible figures to omit or move to a supplement.
Line Comments:
Abstract – check singular/plural subject/verb agreement throughout abstract and the manuscript. There are many incorrect uses. (e.g.: line 2 – a suite…enables, line 4 – surface deformation…is simulated, line 5 - the locations of landslides are)
Line 18 – landscapes don’t encode hazard directly, but they can encode earthquake history
Lines 21-24 – the sentence that starts on line 21 contains incorrect singular/plural subject/verb, other incorrect grammar, and is very long.
35 – Thompson Jobe & Reitman (2025, https://doi.org/10.1029/2024JB029966) also show that earthquake recurrence interval can affect resulting landscape evolution – or maybe this fits better cited in the next paragraph.
80 – Please specify if the Okada surface displacement fields use the topography-corrected version or not?
90 – Confusing for a “fault” component to calculate creep, why not call it the “creep” component? Or perhaps this is related to general comment 1 and an unclear explanation of the interseismic creep functionality, especially early in the manuscript.
94-95: Could omit the sentence that begins “In the sections that follow…”
97-111 – Simplify and condense writing. See example at end of the review.
139 – Can the creep be set to 0? Not all faults creep…
146: “coseismic (“A”)” should be “aseismic (“A”)”
151 – Does every fault need an “I” portion of the fault, or can it have only A and C portions? Does the “I” portion of the fault handle surface response to the interseismic portion of the earthquake cycle? Can a fault have an I portion near the surface, then a C portion, then a lower I portion? Also see general comments 1 and 2.
206 – CAN, not cannot
239 – Quantify “much longer”, for example, is it double or 10x?
241and 244 – Typo: “earthquakes sequence”. Also, omit “described in detail in the following sections” and “as described previously”.
245 – so “Fixed Maximum Magnitude” essentially implements the characteristic earthquake model?
251-253 – does this behavior mean that if a user wants to simulate the central portion of a fault (i.e., one that has a boxcar slip distribution with constant slip throughout the landscape evolution model domain) that they need to make the model fault much, much longer than the landscape evolution model domain?
278 – Omit “but arguably most realistic”
290 – Please explain “percent point function”
306-309 – Simplify this sentence
314 – could omit “that are part of the EarthquakeSequence component”
319 – Is elevation the only “appropriate fields”, or which others?
336 – could omit “a consideration I return to in the discussion”
343 – could omit “hence why…simulation of aftershocks.”
346 – “location of the original parent event” --> does this mean the hypocenter location or the full rupture patch?
Section 4.4 – If using an aftershock sequence, how does it work in conjunction with the original earthquake sequence so that the model doesn’t exceed the moment or displacement cap set by the user? Does using an aftershock sequence make a difference in practice? Also see general comment 4.
368-69 – could omit the sentence that begins “In the following sections,…”
431-32 – could omit “I describe…in the following section, but”
Section 5.2.1 – simplify and condense writing
459-460 – “respective position of the node to with respect to some aspect of rupture location or dimension” --> hypocenter location or rupture patch?
470-480 – simplify and condense writing
495 – Please explain what type of terrain constitutes “Terrain 13”
503 – “PGA base on details of the triggering earthquake” -->Please state what details, e.g., hypocenter location or what?
508-509 – replace “this is left…depending on preferences” with “can be set by the user”
532-524 – simplify and condense
525-235 – using “events” can be ambiguous, please use landslide or earthquake as appropriate.
548-549 – omit “Thus, it is…but rather to” and replace with “Here I”
552-555 – simplify and condense
559 – Omit “(models TC, TFM, TVM, and TVD)” because these have not yet been introduced, so the reader doesn’t know what these models are.
578 – Actually, the most notable difference is the difference in high topography. What is total displacement in each model run?
620-640 – Again unclear if “event” in these paragraphs is coseismic landslide or an earthquake. Be specific.
652 – how are “acceptable levels” determined and what are they?
651-685 – This is a very long paragraph. Consider splitting at line 669 and/or 678
680 – Earthquake directivity effects may also matter for where coseismic landslides occur (e.g., recent Venezuela earthquake)
705-709 – aha! Ok, so flexure is used for normal fault setups to deal with interseismic uplift. What about subduction zone settings?
723 – cite source for mantle relaxation time scale
724-726 – revise for grammar
731 – cite a figure at the end of this sentence
753-755 – Rephrase and simplify the sentence that begins “Similar to normal-sense faults…”
791 – Here and throughout the text, can use “normal” and “reverse” rather than “normal-sense” and “thrust-sense” (e.g., normal fault, normal dip-slip, etc)
834 – 40 km is unrealistic depth for strike-slip faults, which are commonly only 12-15 km deep, some reaching 20 km.
840 – how does total displacement compare for models SSCL and SSVML?
847 – What explains the “decrease in total strike-parallel slip near the fault”? This is NOT expected behavior.
854 – choose a different word for “characteristic”, which is a specific type of earthquake model
892-893 – How does a user know for which scenarios this is the case?
912 – could omit “using the DippingFault…components”
942 – choose a different word for “characteristic”
995 – “earthquake locations”, not “earthquake occurrence”
1010-1012 – yes! Awesome
1020 – does “interseismically creeping portions of seismogenic faults” mean the deep portions? Because some faults creep at the surface, but it’s still unclear if that functionality can be implemented with a locked portion beneath it
1025-1028 – revise for grammar
Figure Comments:
Figure 1: Add “reverse”, ”normal”, ”strike-slip” labels to panels. How deep do the normal and reverse faults extend? In the last line of the caption, “sense OF displacement”.
Figure 2: In the caption, and throughout the manuscript, slip rate is two words, not hyphenated, unless it modifies another word.
Figure 3: Do these two models have the same slip rate specified in model setup? Asking because the total displacement is over double for the clip to moment model than for the clip to displacement model, which is confusing behavior if the user is specifying a slip rate.
Figure 4: Add labels for “clipped by moment” and “clipped by displacement” to the top and bottom rows. In the caption, delete one of the two versions of half (“0.5 half”).
Figure 5: Consider a different color scale in panel d because the sparse M>7.0 earthquakes are difficult to see on the black background. In the caption, delete one of the repeated “bins”.
Figure 6: In the caption, change “text” to “legend” (…different behaviors as described in the legend.”)
Figure 7: Please show total displacement for each run and how much it differs between these four models, as the difference in topography may be related to differences in total displacement. For each model, add a graph of uplift vs model run time. The title for panel b is missing “magnitude”. In the caption, state the maximum magnitude for model TFM.
Figure 8: Consider omitting this figure or moving it to supplementary material, as it’s not central to the manuscript.
Figure 9: Make the plots have consistent y-axis scales so it’s possible to compare different models. In the caption, “example thrust FAULT models”. Consider omitting this figure or moving it to supplementary material, as it’s not central to the manuscript.
Figure 11: In the caption, remind readers what models TVM and TVMLa are so that the figures can stand apart from the text. Add “west of the topographic divide” to the end of the caption. When printed, the two blues are similar. Consider more different colors or shades.
Figure 12: Is the total number of landslides per earthquake realistic for each magnitude? Is this calibrated against real-world empirical data? It seems like a lot of earthquakes, and since the “number of landslides per event” is contained within the model space, it seems possibly too many. In the real world, landslides can occur far from the fault plane, which would be included in real-world data, but should be excluded from data used to calibrate behavior of the CoseismicLandslider component. Additionally, it seems unrealistic that a magnitude 5.0 earthquake will cause any/many landslides, unless it occurs in a stable continental region or an area with site-specific ground motion amplification. Are these taken into account in the CoseismicLandslider component and the model in general? For example, magnitude 5.0 in Australia vs Nevada might have very different landslide responses.
Figure 13 – Same question as Figure 12 about the number of landslides for magnitude 5.0-6.0 earthquakes. Is this realistic behavior? In the caption, change “contour lines” to “dotted lines”.
Figure 14: The red dots show empirical landslide catalogs. Are the colored areas in a and b ALL the simulated landslides or many simulated landslide catalogs? Please clarify in the caption. Also in the caption, please use “earthquake” or “landslide” rather than ‘event’. Event can be either, and in this context it’s confusing language, so please be more specific.
Figure 15 – Why does the normal fault in b extend down to 50 km? It’s an unrealistic depth, as the seismogenic zone rarely goes below ~20 km and is often much shallower. The Global Earthquake Model (GEM - https://hazard.openquake.org/gem/methods/faults/) caps continental seismogenic depth at 25 km, and the USGS National Seismic Hazard Model (NSHM - https://www.sciencebase.gov/catalog/item/62a277acd34ec53d27707325) only has lower seismogenic depths below 25 km along the Cascadia subduction zone. Also, in the caption, change “text” to “legend” (…different behaviors as described in the legend.”)
Figure 16: In the cross-section panels, it’s difficult to see the topography above ground due to the red fault line. Consider showing the fault only below the ground surface. Why is the basin so steep on the non-fault-bounded side – that doesn’t seem like realistic behavior. It would be neat to show some comparison cross sections from normal faults in the real world. Perhaps the Lost River fault near Borah Peak, Idaho, or the Wasatch fault, or a Basin and Range fault in Nevada. Please also show total displacement for each model run.
Figure 17: Please show total displacement for each model. In the caption, please explain what model names mean in English so that readers can understand the figures separate from the text. E.g., “Comparison of model results for normal faults with steady creep (model NCTe30) versus variable magnitude earthquakes (model NVDTe30).” Please also do this for other figures with model names in the captions.
Figure 18: Label the legends with English so the readers know what the models represent (e.g., creep vs earthquakes or with and without flexure). Also, it’s confusing to have the legend for panels a, c, and e split up since all those panels contain the same four models. Put those 4 models in a single legend and show it on each panel or only panel a, or outside the graph area if there isn’t room in the panel.
Figure 19: Explain model names in English in the caption. What causes the extreme high topography on the east/right side of the model space? It doesn’t seem like realistic behavior. It might be neat to show a cross section from a known listric fault (e.g., the Wasatch) for comparison to the real world.
Figure 20: Label the model names in the legend and caption in English so readers can quickly understand the comparisons being made in the figure. Same as in figure 18 – it’s confusing to split the legend between panels when all four models are shown in all panels. Consider if this figure is necessary in the main text or could be moved to a supplement.
Figure 21: Can this figure be larger overall? Difficult to see differences in landscape topography at this small scale. In the caption, explain model names in English. In the last sentence of the caption: “All models have a GRID resolution of 100 m.”
Figure 22: Add graphs of total displacement vs time for each column. What causes the apparent reduction in slip adjacent to the fault plane for the variable magnitude earthquakes model as compared to the creeping model (panels i vs d)? Explain model names in English in the caption.
Figure 23: Explain model names in English in the caption.
Figure 25: Changing the time step effectively changes the recurrence interval of earthquakes since all earthquakes are grouped by time step to calculate surface deformation. This seems to not have much of an effect until the time steps get quite long, which is probably because large earthquakes start to be grouped together for >100 year time steps. Both Reitman et al. (2019) and Thompson Jobe & Reitman (2025) showed that changing the recurrence interval can alter landscape evolution and the expression of faulting, even for identical total slip. Consider discussing the results presented here in context of the earlier studies that noted similar behavior.
Appendix A: Omit “below I review”.
Throughout appendix: Delete all instances of “effectively”, “largely”, and “generally”. They add text without meaning.
Appendix B, line 1127: Quantify “a very long time after”. Why aren’t these aftershocks included?
Table D1: Please add a “total uplift” column. Add “LL – left lateral” to the abbreviations. In the first row in the “Diffusion” column, what does “DDTF” stand for, or should it be DDTD? In the “Notes” column, use “none” instead of “NA”. Why is dx included but not dy? Is dy the same for all models, and if so, what value?
Code Comments:
There aren’t any installation instructions with the github page, nor a list of dependencies. Based on the structure of the code, the .py files could be made globally available by adding them to a PythonPath, but there is nothing hard coded that defines the import command as “efel”. It would be very useful to be able to install with pip.
Example of simplified writing for section 3 Fault Components (lines 97-111): The EFEL model has two fault components: DippingFault and VerticalFault. Each generates a single fault, which is idealized as a set of rectangular panels sharing one or two edges. A DippingFault has a single strike and a constant fault length, with "length" being the fault's dimension along strike. It can have any number of panels, each with its own width and dip. A VerticalFault has a dip fixed at 90° and a constant fault width, with "width" being the fault's dimension along dip. It can have any number of panels, each with its own length and strike. For both components, kinematics are defined separately from geometry by assigning average slip rates in the strike and dip directions. Therefore, the model does not require strike-slip on a VerticalFault or dip-slip on a DippingFault. Strike-slip motion can be assigned to a DippingFault, dip-slip motion to a VerticalFault, or oblique-slip to either by giving non-zero values for both the dip- and strike-slip rates.
Citation: https://doi.org/10.5194/egusphere-2026-4659-RC1 -
RC2: 'Comment on egusphere-2026-4659', Anonymous Referee #2, 03 Oct 2026
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Summary:
This work presents a fault-related tectonic contribution to the surface-process modeling Landlab toolkit. The author developed an elastic fault component, an earthquake component, and a landslide component that allow simulation of interseismic and coseismic deformation, with the capability to generate coseismic landslides. The article explains the theory underlying the components, and it shows a couple of simple applications and findings using the newer contributions.
General Comments
This manuscript adds a fault, earthquake, and coseismic landslide capability to Landlab that many of us in the surface processes community would be interested in using. This contribution is substantial. My main concerns are with the presentation, with how some of the earthquake behavior was chosen, and with how clearly the limitations of the components are communicated to future users.
Length and writing: The article is long, and in my opinion it could be shortened significantly. Many sentences are very long and compound, and the main point often comes late (e.g., the sentence in lines 44–51 has 108 words, not counting references; see also lines 138–142, 635–638 and 644–648). I had to reread several of them to follow the argument. The paper would be much easier to read with shorter sentences, clear subjects, and active voice. Some sections also go into more detail than the main manuscript needs. The Vs30 section (lines 457–493) is one example: it reads as a series of thoughts on different options, some of which the author says are statistically indistinguishable. I would present the approach that was used (Allen and Wald, 2009) and move the rest to an appendix if it is relevant for discussion.
Clarity of the fault setup: The fault geometry section relies only on text, and I found it hard to picture the tip location, coordinates, and the different fault sections. A schematic figure of the model would help a lot, and a brief background on Okada (1992) would make the theory section easier to follow. I would also add a short explanation of the difference between creeping faults and seismogenic faults that generate earthquakes. As I read it, the components can simulate deep interseismic creep and a fully creeping fault, but not a partially creeping fault with shallow creep above a locked section (e.g., the Hayward fault). If that is correct, it should be stated clearly, and the creeping models in Section 5 (line 572) should specify which case they represent.
Earthquake behavior: It is interesting to see the effort to represent the complexity of earthquakes through synthetic catalogs. I am curious what the author considers relevant enough to include as realistic behavior and what they leave out. For example, aftershocks are implemented with the BASS model, but there is no option to place future ruptures in segments that have not yet ruptured ("gap filling"), which existing catalog generators such as RSQSim (Richards-Dinger and Dieterich, 2012) do represent. Tracking rupture centers could also help with the issue described in line 227. In another note, I would encourage the author to use terminology consistent with the earthquake science and tectonic geomorphology literature (e.g., characteristic earthquake behavior for ruptures with a fixed maximum width; triangular facets instead of "iron-like" features). Section 4 could also be reorganized so the three earthquake generation methods are named early, followed by how a sequence is terminated.
Guidance for users: I would ask the author to be very careful with the documentation and tutorials for these components. The manuscript shows that some setups produce unrealistic landscapes, for example when normal faults are used without the flexure component, and strike-slip faults in general (Fig. 21). Users need clear warnings, a list of compatible components, and recommendations so they do not take model artifacts as results. I think some of these findings and warnings belong in the abstract, where they are currently missing. Related to this, I wonder if the flexural correction could be built into the NormalFault component as a method, and whether the strike-slip application is ready to be shared without stronger caveats specifying the components that would work best with it (LateralEroder) (line 880).
Figures and structure: To shorten the paper, I suggest combining figures that show results from the same models (e.g., Figs. 7–9, Figs. 10–11, and Figs. 12–13), and turning Sections 6.2–6.3 into a short section with general recommendations for using the components, including the most efficient computing methods and timestep choices.
Finally, a broader question for the author: what new findings come out of the added complexity that could not be captured with simpler fault models? Making this clear in the introduction and conclusions would strengthen the case for the paper.SPECIFIC COMMENTS
Line 44–51: This sentence could be split into several shorter sentences. It is so long that it obscures the meaning.
Line 76–79: How is this topographic correction for surface velocities relevant? Please clarify.
Line 81: If the goal is to explain the theory, I suggest including the minimum background needed to understand Okada (1992), maybe with a figure illustrating the different components. Please also clarify that if the tensile component is zero, it is a pure shear dislocation model.
Line 83: Briefly explain what the AdvectionSolverTVD does before stating that it uses the horizontal velocity components.
Line 105: In what units?
Line 116: It would be useful to illustrate the x, y, z coordinates of the tip location as an example in Figure 1. More generally, the section on fault geometry is hard to visualize because it relies only on the text description.
Line 117: What does it mean that "instances of DippingFault are not constrained to being within the Landlab grid"? Does this mean the tip location can be outside the grid? How does that work? Could you clarify?
Line 138–142: This is another very long sentence that is hard to follow. Please split it into shorter sentences.
Line 146: Since the "A" section cannot creep, does this mean the model cannot simulate faults that creep freely at the surface? It simulates deep interseismic creep but not creeping faults. Is that correct?
Line 156: Neat contribution of this work.
Line 165: So this could simulate a fully creeping fault, but it would not allow a partially creeping fault, with shallow creep above a locked seismogenic section and creep again below the locking depth (e.g., the Hayward fault with aseismic creep). Is that correct?
Line 171: A figure would make this coordinate and tip assignment easier to understand.
Line 192: What are the three different methods? Please specify. It would help to name the three earthquake generation methods earlier. After reading Section 4, I still was not sure whether all generated earthquakes have the same magnitude.
Line 199–201: How different are stable continental dip-slip and interplate dip-slip faults in the Landlab simulation? I understand that the rupture scaling relationships differ, but how is the geometry or setting represented differently in Landlab?
Line 205–208: I suggest rewriting and shortening to avoid repetition, for example: "Individual ruptures on the fault plane must be centered within the coseismic portion and not extend beyond the fault dimensions."
Line 207: How important might it be to control rupture location based on where sections have already ruptured? In other words, do you think it would be interesting to allow ruptures in segments that have not ruptured previously, to simulate "gap filling"?
Line 227: Could this be prevented by tracking the centers of rupture and triggering following sequences on segments that have not ruptured?
Section 4: This section could be reorganized to make it easier to follow. Start with the earthquake generators, then explain how the earthquake sequence is terminated. I am also still unsure whether truncation is the best approach to avoid exceeding the seismic moment.
Line 242: Requiring the total duration of the Landlab run and of the earthquake generator (which runs before the Landlab simulation) to match sounds a bit like hard-coding. What happens if the catalog is shorter? Does the model run anyway?
**A fixed maximum rupture width sounds like characteristic earthquake behavior. Would it be easier to use common vocabulary between the EQ community and geomorphologists?
Figure 5: Looking at panel d, is it possible to have more than one event at the same time on different segments of the fault? Or does the way the model triggers earthquakes ensure there is only one event at a time?
Line 457: Consider using "Average shear wave velocity estimation" in the section title instead of Vs30.
Line 465: What does it mean to be classified as terrain 13? This whole section on Vs30 reads like a series of thoughts and complexities. I suggest simplifying it in the model implementation and, if relevant for discussion, moving it to an appendix.
Line 469–484: This section goes into more detail than I think is needed in the main manuscript. I would only present the approach that was used (Allen and Wald, 2009), since its resolution is comparable to that of landscape evolution models.
Line 493: Why include these options if they are statistically indistinguishable? This paper adds a fantastic contribution to Landlab, but the number of methods available might lead to unnecessary complexity for users, which the author also acknowledges.
Line 525: It is still unclear how the model treats individual coseismic landslides when more than one occurs in a single timestep. Does the component change the timestep internally (fractional timesteps), so that we see the chain effect of one event followed by another based on how the topography changed after the first?
Line 559: What does the model nomenclature stand for? Please include it, e.g., TC: Thrust Creeping; TFM: Thrust Fixed Maximum magnitude; TVM: Thrust Variable magnitude clipped by total seismic Moment; TVD: Thrust Variable magnitude clipped by maximum Displacement.
Line 572: I am still unsure how the creeping fault is modeled. From the methods, it seems the whole 25 km is creeping. This would represent a fully creeping fault, like the central creeping section of the San Andreas, which is a valid end-member. However, many creeping faults are only partially coupled, with shallow creep above a locked section. It would help to state which case the creeping models represent and whether the partially creeping case can be simulated.
Line 575: I assume the surface process parameters were kept the same across models? Please state this. Also specify whether the left and right grid boundaries are open, and any other configuration that would help readers understand the topographic patterns.
Figure 6: Maybe I missed this, but does the fault length need to be larger than the model domain? Is there a particular reason the figures show a smaller landscape evolution model domain than the fault structures?
Figure 7: I suggest including the initial steady-state topography so readers can see the changes in the four scenarios.
Figures 8–9: I would consider combining these results into a single figure, possibly together with Figure 7, to reduce the total number of figures. If these three figures show results from the same models, one figure might capture the results more effectively.
Figure 10: Great finding! Keep this figure. I suggest adding a heat map of landslide locations through model time for TVMLa. It is interesting to see changes on the east side of the divide in the elevation difference. Are those driven by landslides or other factors? I assume this case did not include stochastic bedrock landslides, right?
Figure 11: I also suggest combining this with the previous figure. If the time evolution is important, the panels could be included as they are. If not, a map highlighting the differences might be enough.
Figure 12: I would combine this with Figure 13, or remove it as a standalone figure if it shows expected behavior, with the goal of reducing the length of the paper.
Figure 13: Panel b could be shown in panel a using different symbols for the simulated earthquakes and the compilation.
Line 627: I read this line three times to understand it. Please revise it to make clear that the simulation domain is too small to capture larger ruptures like those observed in nature.
Line 635–638: Please revise this sentence. It is long, with a nested parenthetical clause, and the main point gets lost.
Line 644–648: Another sentence that is exhausting to follow. The reader needs to keep a lot of information in mind before reaching the verb. The main action of this sentence is "highlight," and it comes very late. Please consider editing the writing style across the whole manuscript.
Line 706: Is there any constant uplift applied across the grid in the model loop?
Line 723: Please cite or justify the choice of 2500 yr for the mantle relaxation time.
Line 736: Are the creeping models producing steeper topography than the earthquake models? It does not look like it in the thrust results on the side facing the fault. Do you mean for the whole landscape?
Figure 16: It is very interesting to see how topography changes with the effective elastic thickness.
Figure 17: Please specify in the caption that panel c is the model topography after 1 Myr of simulation with earthquakes.
Figure 18: Could you also explain what NC and NCTe10 mean in the caption?
Line 745: It is unclear to me how users will use the NormalFault component if it requires the flexure component to work realistically. Would it be useful to incorporate this correction as a method within the NormalFault component?
Line 785: Cool solution to avoid adding the same topography.
Line 791: In the paragraph starting "Additionally..." (through Fig. 21), the core finding gets buried. The key result is that strike-slip models using these components fail to reproduce natural-looking landscapes, but this is delayed by a long introductory contrast with the normal and thrust scenarios. Please rewrite.
Figure 21: Given the unrealistic results, I am not sure it makes sense to consider applying this model with the fluvial components. If it only works more realistically with LateralEroder, then it would not explicitly track sediment, right?
Line 838: Are the thrust and normal fault domains not subject to general uplift across the whole domain, in addition to the differential uplift/subsidence from the fault?
Figure 22: What is happening around the corners of the variable magnitude models? Why is there so much subsidence/erosion there? The author mentions that it reflects the rupture tips, but I wonder if it is related to how the model adds topography when the fault is displaced. If topography is already low, the mean topography will be low, and the model will keep adding low relief to the corner.
Line 880: I am worried about sharing this contribution openly without warnings, since it may lead users to create unrealistic landscapes and, if not used with care, produce artifacts that might be interpreted as results.
Sections 6.2–6.3: Considering the length of the article, I suggest restructuring these sections as general recommendations for using the components, briefly presenting the most efficient computing methods and timestep choices.
TECHNICAL CORRECTIONS
Line 12: Typo, "seismogenic strike-slip faults".
Line 121: Should be "a fault that goes above the zero surface cannot be defined".
Line 129: "slip rate", not "slip-rate".
Line 303: Delete the space before the period.
Line 374: Typo, "hillslope".
Line 705: "footwall", not "foot-wall".
Line 714: "In detail (...), never reach, the total flexure": please rewrite. The sentence is grammatically awkward and missing an article.
Line 729: Consider "triangular facets" instead of "flat-iron like".
Line 803: Should be Duvall and Tucker, 2015.
Line 808: Typo, "strike-slip fault".Citation: https://doi.org/10.5194/egusphere-2026-4659-RC2
Model code and software
EFEL v1.0.0 Adam M. Forte https://doi.org/10.5281/zenodo.21744823
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