The Landers earthquake of June 28, 1992

Coseismic Study

The image is an interferometric map of the Landers, 1992 earthquake area showing the ground displacement along the radar line of sight. One full color cycle represents here 5 cm of range displacement. Gray areas are zones of low phase coherence that have been masked before unwrapping. Solid lines depict the 1992 surface rupture, after Sieh et al. (1993).
The topographic phase has been removed using a combination of the USGS 30 m and 90 m digital elevation maps. The precise orbits from the ESA D-PAF were used to determine the interferometric baseline and to flatten the map. Processing from RAW data to interferogram and geocoded map was done using the JPL/Caltech ROI_PAC software package. The radar data were acquired by the European Space Agency ERS-2 satellite on April 24, 1992 and June 18, 1993.

Full resolution JPG image (0.5 MB)

Figure 1: The June 28, 1992, Mw=7.3 Landers, California earthquake produced a surface break of ~70 km long with up to 6.2 m of right-lateral offset. This picture shows a section of the 1992 scarp along the Emerson fault (Photo: G. Peltzer).

Figure 2a: ERS-1, 3-pass interferogram showing the co-seismic, static displacement produced by the Landers earthquake. One color fringe represents 28 mm of displacement of the ground along the satellite line of sight. White line is surface rupture. Black mask covers areas of poor correlation preventing unwrapping of topographic phase field. Boxes indicate areas of Figures 2b and 2c. ERS-1 SAR data: European Space Agency - Processing: Jet Propulsion Laboratory.

Figure 2b: Detail of figure 2a in stepover between the Johnson Valley and Homestead Valley fault. Dense fringe pattern parallel to the Johnson Valley fault is consistent with block tilting, down to the west, of 1/100 degree (Peltzer et al., 1994). Figure 2c: Detail of figure 2a in surface rupture gap between southern Johnson Valley and Eureka Peak faults. Dense fringe pattern in the gap indicates that slip occurred at depth along this section of the fault and is consistent with 1.5-3.5 m of right-lateral slip and a locking depth of 1.5 km (Peltzer et al., 1994).

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Figure 2b: Detail of figure 2a in stepover between the Johnson Valley and Homestead Valley fault. Dense fringe pattern parallel to the Johnson Valley fault is consistent with block tilting, down to the west, of 1/100 degree (Peltzer et al., 1994).	Figure 2c: Detail of figure 2a in surface rupture gap between southern Johnson Valley and Eureka Peak faults. Dense fringe pattern in the gap indicates that slip occurred at depth along this section of the fault and is consistent with 1.5-3.5 m of right-lateral slip and a locking depth of 1.5 km (Peltzer et al., 1994).