Research about Motagua fault

USGS1978

Documentation for alinement arrays, Motagua fault, Guatemala

The following brief report documents the locations and surveying data for four alinement arrays (fig. 1, p.-7-19) across the Motagua fault, Guatemala, which were installed to measure afterslip occurring along the fault. The arrays represent new monuments installed in areas where displacements had been measured as early as four days after the earthquake. The results of those measurements are reported by Bucknam and others (1978). Because of lack of monument stability, the susceptibility to damage of the various monuments used in the earlier work, and the need for more precise measurements because of decreasing rate of slip, the new monuments were installed at the four sites in May 1978.

Motagua fault↗

USGS1977

The Guatemala earthquake and Caribbean Plate tectonics

The main fault along which the destructive Guatemala earthquake occurred was the Motagua fault. Ground breakage was observed in a continuous, well-defined line for 230 km. At its closest point, the fault is 25 km north of Guatemala City. Surface displacement across the fault was dominantly horizontal and sinistral (see back cover). The strike-slip component averaged 1.08m and was as high as 3.40m. Unlike many other earhtquake-related strike-slip displacements in the world (such as the San Andreas system in California), subsidiary faults, splays, and an echelon offsets are relatively rare along the Motagua fault. Most of the fault trace is marked by linear stream valleys, minor scarps, shutter ridges (a fault-displaced ridge which "shuts in" the adjacent canyon), and sag ponds (fault-formed depressions which fill with water).

Earthquake Information Bulletin (USGS)↗