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Model-of-EQIL-distribution-area

This project aims to create a simulation model for the earthquake-induced landslide (EQIL) area near Zagreb, Croatia to predict the extent (or reach) of the possible landslide (EQIL) triggered by Medvednica mountain’s orogeny.

Landslides are mass movements of soil and rocks along a slope. Landslides occur when the shear strength of the hillside material decreases due to an increase in the shear stress of the slope, or due to processes of change in the natural ecosystem caused by anthropogenic activities (Moresi et al., 2020). Sometimes, landslides can be caused by human activities, or more so, they can modify the threshold of occurrence of landslides by accelerating the dynamics of natural processes (Sidle & Bogaard, 2016). They can cause severe damage, and while most of them occur slowly over time, the most destructive ones happen suddenly after being triggered by an event such as earthquakes or heavy rainfall (Conners, 2019). Earthquake-induced landslides (EQIL) are the most destructive secondary natural hazards associated with earthquakes and are also the focus of this paper (Jibson, 2007).

This research presents a study that aims to estimate earthquake-induced landslide distribution area and to scrutinize its area-wise morphological characteristics. The results show the estimates for the Zagreb/Zagorje region in Croatia. In this region, the Medvednica mountain orogeny triggers seismic events which may potentially lead to earthquake-induced landslides. This research raises the question: What is the EQIL distribution area in the Zagreb/Zagorje (Croatia) neighborhood and what is specific for it in terms of terrain characteristics? To answer it, we estimate the distribution area of an EQIL induced landslide in the region of Zagreb, Croatia, and study its morphological characteristics.

This kind of research is relevant in terms of avoiding the possible effects of such natural disasters. Those effects can include road crashes and debris falling which may cause deaths or destroy properties. Governments and insurers can benefit from estimating earthquake-induced landslide (EQIL) distribution areas by including their risk while developing the infrastructure or selling insurance. Furthermore, residents should also know about the possible dangers of living in such areas.

The structure of the application

The main program uses the functionality of other modules, gradually creating the outputs used in this analysis. The following general overview of the main driver's flow explains the operations performed in order to build the simulation model. Each module has a certain task to perform:

  1. mapProximity: create_proximity_map function
    • computes and visualizes the EQIL distribution area for the region of interest.
  2. unifyResolutions
    • The resolutions of rasters are unified to follow the smallest, most detailed resolution.
  3. cropToDEM
    • The rasters are adjusted to the area of interest (digital elevation model map - DEM)
  4. translateToMap
    • The .tif layers are translated to the format recognized by PCRaster library.
    • The outputs are binary rasters on which further operations will be performed
  5. extractZone
    • Prepares to include the values only from a certain area, in this case:
      • area within PGA 0.12g contour
      • area of the simulated EQIL distribution area
      • ground failure area estimated by USGS
  6. morphologicalStatistics
    • Computes area-wise statistics for the area of interest:
      • Six morphological variables: topographic wetness index (TWI), profile curvature, vector ruggedness measure (VRM), local relief, slope, distance to streams
      • mean, median, min, max, standard deviation, variation are computed
      • The statistical computation contain experimental part performing its operations using Numba just-in-time Python compiler
  7. plotMorphology: visualize_csv function
    • produces visualizations of the 6 morphological variables' values distributions. Uses the CSV files containing these values for the 4 areas of interest:
      • area within PGA 0.12g contour
      • area of the simulated EQIL distribution area
      • ground failure area estimated by USGS
      • entire study area

Example results

alt text

0 directory terrain_variable mean_value variance_biased variance_unbiased standard_deviation_biased standard_deviation_unbiased max_value min_value median_value
1 PGA_zone dem 201.94863257257387 17079.648327961608 17080.200477715203 130.6891285760281 130.69124101375425 993.0 82.0 157.0
2 PGA_zone distance_stream_downstream 13901.147484686871 117626576.87123239 117631116.33468066 10845.578678486105 10845.787953610408 41508.4 0.0 11114.157
3 PGA_zone local_relief 3.3305738600615915 8.717205243711724 8.717493912009086 2.9524913621739395 2.952540247314012 9.0 1.0 1.0
4 PGA_zone profile_curvature 0.11128384083136816 3514.897502003044 3515.0129034575716 59.286571008981824 59.28754425220842 6686.0767 -6033.268 -2.7533576e-06
5 PGA_zone slope 3.5090130031539903 18.6773326575407 18.677938710258513 4.321727971256486 4.321798087631873 30.360462 0.0 1.8577819
6 PGA_zone TWI_raster -13.016356720274482 4.404441835135551 4.404584359868914 2.0986762101704852 2.098710165761083 -4.9608107 -17.829576 -13.03805
7 PGA_zone vector_ruggedness_measure 0.0017229498014403985 1.2117352018472649e-05 1.2117743747435842e-05 0.0034809987099211413 0.0034810549762156646 0.047728363 9.271834e-08 0.00037510128
8 ground_failure_zone dem 774.4444444444445 3574.135802469136 3784.3790849673205 59.78407649591265 61.51730719860323 876.0 656.0 774.5
9 ground_failure_zone distance_stream_downstream 15269.94775390625 23684853.1151668 25078079.76900014 4866.7086532036 5007.801889951333 26276.666 12655.301 13266.959
10 ground_failure_zone local_relief 2.7777777777777777 0.17283950617283958 0.1830065359477125 0.4157397096415491 0.4277926319464987 3.0 2.0 3.0
11 ground_failure_zone pga_contour_raster_cropped 0.2724381486574809 9.888122256788523e-05 0.00010469776507187848 0.00994390378915068 0.010232192583795444 0.29956156 0.26 0.26934892
12 ground_failure_zone profile_curvature 6.398951930306238e-07 3.5080181788444543e-13 3.714372189364716e-13 5.922852504363463e-07 6.094564947036594e-07 2.3903008e-06 8.7693635e-08 4.492072e-07
13 ground_failure_zone slope 24.425234370761448 6.276500191140483 6.645706084736982 2.505294432026001 2.577926702747187 28.02322 19.12525 24.929588
14 ground_failure_zone TWI_raster -15.70289765463935 0.4878731211233206 0.5165715400129277 0.6984791486675322 0.7187291144881552 -14.334189 -17.10681 -15.754505
15 ground_failure_zone vector_ruggedness_measure 0.0065969138457957245 1.113066037581076e-05 1.1785405103799628e-05 0.003336264434335318 0.003432987780898678 0.014293254 0.0027362937 0.0051409993
16 EQIL_distribution_area dem 720.5886075949367 15239.01430059286 15287.392123769345 123.446402542127 123.64219394595578 981.0 404.0 720.5
17 EQIL_distribution_area distance_stream_downstream 22621.837090214598 8892256.003877142 8920485.388016436 2981.9885988845 2986.718163472482 27561.291 12633.724 21406.955
18 EQIL_distribution_area local_relief 4.1835443037974684 3.181501361961223 3.1916013662849094 1.7836763613282605 1.7865053501976729 9.0 2.0 5.0
19 EQIL_distribution_area pga_contour_raster_cropped 0.2906822777247127 0.0001627926208497987 0.00016330942282075044 0.012759021155629404 0.012779257522280018 0.3195611 0.27278692 0.28980446
20 EQIL_distribution_area profile_curvature 1.0127504615122613e-05 1.1250372185392921e-08 1.1286087652648136e-08 0.00010606777166223923 0.00010623599979596435 0.001764685 -4.1868538e-05 2.41667e-09
21 EQIL_distribution_area slope 14.306402396552171 16.316898041568045 16.36869771789048 4.039418032534891 4.045824726540991 25.352772 2.1681957 14.60791
22 EQIL_distribution_area TWI_raster -15.105869250961497 2.4253059383153044 2.4330053222464643 1.5573393780147295 1.5598093865105647 -10.349417 -17.52993 -15.439365
23 EQIL_distribution_area vector_ruggedness_measure 0.01002197717228032 3.7511528433965274e-05 3.7630612651215957e-05 0.0061246655773164686 0.006134379565303728 0.034200232 0.0012128265 0.008357128
24 binary_maps dem 166.49553249097474 10020.997302544807 10021.14804183545 100.1049314596679 100.10568436325407 993.0 82.0 136.0
25 binary_maps distance_stream_downstream 15698.401448677438 155459096.3094637 155462729.97461832 12468.323716902112 12468.469431915784 52587.348 0.0 12391.461
26 binary_maps local_relief 2.462098642833499 6.698877952525168 6.698988826223053 2.5882190696548792 2.5882404884830645 9.0 1.0 1.0
27 binary_maps pga_contour_raster_cropped 0.13252297116305667 0.004558252954325568 0.004558321521135452 0.0675148350684912 0.06751534285727542 0.33603898 0.042996094 0.1162887
28 binary_maps profile_curvature -0.05978386853516508 2318.8650979773934 2318.9022551087724 48.154595813664486 48.15498162297202 6686.0767 -6033.268 -5.759689e-06
29 binary_maps slope 2.4949044712529873 11.90447348644623 11.904655375756786 3.4502860006738905 3.45031235915776 30.360462 0.0 1.0841638
30 binary_maps TWI_raster -12.86445018227667 3.7055675998110598 3.705623464604291 1.9249850908022794 1.9249996011958785 -4.9608107 -17.829576 -12.837674
31 binary_maps vector_ruggedness_measure 0.0010539718699024707 6.977321516756148e-06 6.977426472027989e-06 0.0026414620036555795 0.0026414818704711923 0.047728363 -2.107556e-08 0.000107259046