JAKARTA: A total of 93 aftershocks have been recorded, with tsunami waves observed following a magnitude 7.6 earthquake that struck waters off North Sulawesi earlier on Thursday (April 2).
Meteorology, Climatology and Geophysics Agency (BMKG) head Teuku Faisal Fathani said the aftershocks, recorded up to 12 noon, ranged in magnitude from 2.8 to 5.8, with seven of them felt by residents.
He said BMKG continues to monitor the frequency of aftershocks, noting that their duration could vary.
"Usually, after one or two days, we will study the trend, whether it ends within one week or sometimes two weeks, depending on the situation,” he told a press conference, on Thursday.
The magnitude 7.6 earthquake struck at 6.48am local time (WITA), with its epicentre located at sea at 1.25 degrees north latitude and 126.27 degrees east longitude, at a depth of 62km, and was strongly felt in Manado and surrounding areas.
BMKG reported that tsunami waves were detected after the earthquake, with sea levels rising by up to 0.3 metres in West Halmahera and 0.2 metres in Bitung.
Teuku Faisal cautioned that in some cases, such as the 2018 Sulawesi earthquake and tsunami, aftershocks could be stronger than the initial quake, adding that the situation continues to be monitored at BMKG’s Multi-Hazard Early Warning System centre in Kemayoran.
He said sea level monitoring was conducted using nine tide gauges, including three operated by the Badan Informasi Geospasial (BIG), allowing authorities to track tsunami heights at multiple locations.
He added that while recorded wave heights may appear small, geographical conditions in North Maluku and North Sulawesi, including the presence of small islands and bays, could amplify tsunami waves and their propagation beyond initial estimates, warranting continued warnings.
Separately, the National Disaster Management Agency (BNPB) head Suharyanto said initial reports showed limited impact, with one fatality recorded in Manado and one person sustaining minor injuries in Minahasa.
He said about 16 households were affected in Minahasa, while several buildings, including government offices, a hotel and a KONI (Komite Olahraga Nasional Indonesia) building in Manado, were also damaged, adding that damage was also reported in Minahasa and Ternate, while assessments in Bitung were still ongoing.
Suharyanto said North Sulawesi and North Maluku are among regions with high earthquake and tsunami risk, noting that historical records dating back to 1608 show frequent major quakes, often above magnitude 7, including a magnitude 7.7 event in 1998.
He said authorities, including local governments, the military and police, must continue to remind communities to remain vigilant and improve preparedness.
According to him, the government, through BNPB and BMKG, has strengthened early warning capabilities over the past four years, including the installation of tsunami early warning systems along coastal areas, as well as the development of operation control centres and warning sirens.
He added that early warning sirens were activated following Thursday’s quake, helping provide initial alerts to communities, including the potential for tsunami.
Suharyanto said damage data provided so far remains preliminary and subject to updates, urging authorities to continue verification and data collection as assessments progress. - Bernama
