This electronic supplement includes (1) a color-coded elevation model (Fig. S1) showing the 1887 rupture trace; (2) a satellite image (Fig. S2) showing the major Basin and Range Province normal faults of the study area; (3) a color version (Fig. S3) of the geologic map showing the rupture trace of the 1887 earthquake along the Otates fault (Fig. 4); and (4) several additional photographs of the 1887 rupture scarp (Figs. S4 to S10, from south to north), which may help in future field studies to locate these scarp outcrops and to document the scarp erosion with time.
Download: Archive of all 10 figures (High-resolution TIFFs) [Zipped TIFF Files; 74.4 MB MB]
Figure S1. Elevation model of northeastern Sonora showing in red the rupture trace of the 1887 earthquake (P: Pitáycachi segment; T: Teras segment; O: Otates segment). Closed circles: population centers; open circles: abandoned mining settlements; dashed east-west line: international boundary. The large frame defines the area covered by Figure S2, the intermediate-size frame the area covered by Figure 4, and the small frame the area covered by Figures 4 and S3. Elevations reach ~2,440 m asl in the Sierra El Tigre and ~2,760 m asl in the Sierra Madre Occidental.
Download: High-resolution version of Figure S1 [Zipped TIFF File; 2.2 MB]
Figure S2. Ortho-rectified Landsat-7 ETM+ false-color image (Path34Row39 Bavispe, band combination 741-RGB, pixel size 25 m, acquisition date 2001-01-11) of Sierra El Tigre, showing (in white) the traces of major normal faults (1: Pitáycachi; 2: Teras; 3: Otates; 4: Palmita; tadpole symbols on hanging wall) and structures (5: El Tigre horst; 6: Otates basin; 7: Iglesitas horst; 8: Angostura basin) based on preliminary fieldwork by the author. Also shown (in red) is the 1887 earthquake rupture trace. The frame defines the area covered by the geologic map (Figs. 4 and S3). The higher elevations are covered by snow. Sierra El Tigre is delimited by a horseshoe-shaped bend of the Bavispe River. The towns most severely damaged in the 1887 earthquake, Bavispe and Villa Hidalgo, are located on alluvium of the Bavispe River. The southern (and possibly also the northern) termination of the Otates rupture segment is controlled by a NW-SE striking cross fault. Squares: population centers; circles: abandoned mining settlements.
Download: High-resolution version of Figure S2 [Zipped TIFF File; 27.4 MB]
Figure S3. Geologic map showing the measurement sites on the rupture trace of the 1887 earthquake along the Otates fault. Open areas are unmapped. The trace and the measurement sites are highlighted in red.
Download: High-resolution version of Figure S3 [Zipped TIFF File; 1.9 MB]
Figure S4. View of the 1887 rupture scarp about 30 m south of site 79 (Fig. 4). In the foreground (north) the scarp is a 76° W dipping fault plane on bedrock (rhyolite) with faint vertical striations and a 110-cm high free face. In the background (south) the scarp has a comparable size free face in somewhat consolidated (cemented) scree with clasts as much as 20 cm in diameter. Notebook for scale (21 cm long).
Download: High-resolution version of Figure S4 [Zipped TIFF File; 6.1 MB]
Figure S5. Photograph looking west at Los Alisos Canyon (Fig. 4) and the scarp along the central part of the Otates fault, where the topographic relief of the fault escarpment and the surface slope angle adjacent to the rupture (Table 1) reach a maximum. Here the fault separates rhyolites of Sierra El Tigre from Báucarit Formation (horizontal layers in foreground) and basalt (hill in left middle ground) of the Higueras basin. Preserved traces of the 1887 surface rupture are limited in this area to two spurs (sites 24 and 30 on Fig. 4); the remainder of the rupture is buried beneath scree.
Download: High-resolution version of Figure S5 [Zipped TIFF File; 5.7 MB]
Figure S6. Photograph looking south along the central part of the Otates fault showing part of the 1887 surface rupture that exposes coarse and poorly stratified scree on a spur (site 30 on Figs. 4 and S3). The free face is 140 cm high (hammer for scale). The mountain front in the middle ground is covered by fresh, unvegetated rock debris.
Download: High-resolution version of Figure S6 [Zipped TIFF File; 5.6 MB]
Figure S7. Photograph looking north along the northern part of the Otates fault, which separates footwall rhyolitic rocks of the Sierra El Tigre from scree. The horizontal arrow marks the 1887 surface rupture at site 21, and the vertical arrow indicates the northern end of the mapped surface rupture. The rupture follows a steepening of slope in the talus, suggesting prior movement along this trace. As at sites farther south (Fig. 6), the footwall of the Otates fault is deformed by closely spaced fractures and secondary faults.
Download: High-resolution version of Figure S7 [Zipped TIFF File; 5.7 MB]
Figure S8. Close-up view of the 1887 rupture, 50 m north of site 18 (east of El Ranchito, Fig. 4) in coarse, poorly stratified rock debris. The free face is 160 cm high (33 cm hammer for scale).
Download: High-resolution version of Figure S8 [Zipped TIFF File; 7 MB]
Figure S9. Eastward view from near Los Otates ranch showing rhyolites of Sierra El Tigre, the Otates fault, and remnants of the 1887 rupture scarp (indicated by arrows at sites 18 to 21, Fig. 4).
Download: High-resolution version of Figure S9 [Zipped TIFF File; 5.8 MB]
Figure S10. View of the 1887 rupture scarp at site 29, near the northern end of the Otates segment and the outcrop of Permian limestone (Fig. 4). The free face, which is developed in calcium-cemented rock debris, is 160 cm high (33 cm hammer for scale).
Download: High-resolution version of Figure S10 [Zipped TIFF File; 7 MB]
