Recent deformation at the junction between the North Luzon block and the Central Philippines from ERS-1 Images

Abstract The transfer of the major part of the motion between the Philippine Sea Plate and the Sunda block is accommodated along a north-west shear wide zone partly on the Philippine Fault and partly on the Sibuyan Verde Passage Fault (SVPF) as indicated by global positioning satellite and geological data. Given the limited motion along the SVPF and the important motion along the Philippine Fault, as well as the necessity of a connection between these faults and the southern Manila Trench, a transtensional motion along the northeast-southwest Macolod Corridor (MC) may be predicted. We used synthetic aperture radar European remote sensing (SAR ERS-1) images to analyze the volcano– tectonic features of this area, because these images are sensitive to minute textural or topographic contrasts resulting from small effects of recent deformation. In addition, they allow us to determine accurately the shape of the base of volcanic edifices and to detect linear clusters of very small adjacent cones. The results presented herein allow us to extend the features recognized earlier to a larger MC. Large faults actually connect the Philippine Fault to the Sibuyan Verde Passage Fault all across the Taal Volcanic Field. In addition to extension along north-east faults, we identify an important component of left-lateral strike–slip underlined by fault scarps, dykes, alignments of volcanoes and pull-apart basins, accompanied by extension along north-south faults. A relative chronology of the fractures and volcanic edifices is proposed. When compared to the existing ages of the volcanics, an evolution scheme of the area may be proposed, according to which extension shifted from a nearly north-south opening between 5 and 2 million years to a direction close to east-west at Present. The early north-south extension existed in the Marinduque Basin and may have migrated northward and rotated to the present MC.