An earthquake which occurred off the northern Mozambique gives a peculiar feature of P‐waves recorded by WWSSN long period instruments. All the P‐waveforms can be divided into two parts: the amplitude of the first arriving phase varies from station to station, which is consistent with the normal fault type solution of the Harvard CMT solution determined by the long period GDSN data. The amplitude of the second phase, in contrast, is fairly constant over all the stations, inconsistent with the normal fault solution. From these observations and data analyses, we propose that the source process of this event is a combination of a normal fault and a subsequent isotropic source starting with an explosion followed by a contraction or a corruption with each net moment of 2 ∼ 3 × 1025 dyne.cm at the assumed depth of 7.5 km. Our image of these source mechanisms is consistent with the known geological setting around the epicenter: grabens with many dikes or intrusions.