Circum-Pacific faulting in the Philippines-Taiwan Region

Conflicting views of circum-Pacific Tectonics have focused on the Philippines-Taiwan, where there has been neither convincing documentation nor general on the importance of transcurrent (strike-slip) faulting or the possible of regional horizontal displacement. Structural and physiographic features of 1200-km-long Philippine fault zone are fully as spectacular as those of the -known San Andreas and Alpine faults, and current activity is indicated by localities in which scarps cut Recent gravels. Predominance of horizontal over displacements is indicated by linearity of the fault trace, failure of one side be consistently higher than the other, disregard for gross physiography, and scissoring individual scarps within the zone. Consistent stream offsets on Luzon, , and Leyte demonstrate unequivocally that the sense of Recent displacement been uniformly sinistral (left-handed). The Philippine fault has no obvious relationship to active volcanoes, but the parallelism and proximity of the to the Mindanao trench suggest a close causal relationship. The remarkable Valley of eastern Taiwan represents another great transcurrent fault to the western Pacific rim, and ground displacements during historic earthquakes a sinistral sense of displacement here as well as in the adjacent Philippines. study does not support the hypothesis of counterclockwise rotation of Pacific basin, but more important is the further documentation of the predominance transcurrent faulting in active circum-Pacific orogenic areas. These results field studies in Alaska, California, Chile, and New Zealand, as well emphasizing the geological reasonability of the results of seismic fault-plane solutions the world-wide predominance of transcurrent movements.