The Samar cluster is named for the island of Samar in the Philippines.
It includes events in the subduction zone under the eastern part of the
island, reaching a depth of ~160 km, and a linear NW-SE-trending belt of
seismicity at crustal depths to the west. The cluster includes three M6
events, on October 26, 1980 (6.3 Mw), February 15, 2003 (6.2 Mw) and
August 18, 2020 (6.6 Mw). A relatively large area had to be included to
obtain adequate azimuthal coverage for location calibration. All
earthquakes have depth control from near-source and local-distance
readings and about half of them also have teleseismic depth phases that
are generally in agreement.
