An earthquake measuring 3.7 on the Richter Scale shook several parts of Trinidad again yesterday. The Seismic Research Unit at St Augustine said, however, the tremor was actually an aftershock from last Friday's earthquake. The quake yesterday occurred at 12.05 a.m., 30 kilometres north of Trinidad. It was felt in several areas including San Juan, Mt Hope and Diego Martin It had a focal depth of approximately 32 kilometres and was one of six aftershocks that have been recorded since Friday's earthquake. The preliminary location for the quake was 11.10 degrees north, and 61.65 degrees west. On October 28, at 6.30 p.m., an earthquake measuring 5.0 on the Richter Scale occurred, and was felt throughout the northern, central and southern regions of Trinidad. The focal depth was measured at 5 kilometres and it was reportedly felt as far away as Grenada and St Vincent. Scientists at the Unit have reviewed additional seismic information since last Friday, and have advised that the focal depth was 5 kilometres, and not 22 kilometres as previously stated. On October 24, a magnitude 4.9 earthquake occurred at 5.20 a.m. about 75 kilometres north-west of Port of Spain. It was felt in northern and central Trinidad, including Glencoe, Port of Spain, Maracas Valley, St Augustine, Arouca, and Claxton Bay. It was also reportedly felt in Grenada. The Unit said the area north of the Paria Peninsula generated earthquakes at a faster rate than that north of Trinidad. The Seismic Unit added that the earthquakes followed normal patterns.