The earthquake in question, in 1861, had a magnitude of at least 8.5. It also caused tsunami waves and killed thousands.
at a study Posted at the beginning of the month in the review natural earth sciences, a team from Nanyang Tech University in Singapore, describes this ” slow earthquake A phrase commonly used in seismology, but never for something very long. Instead, most known slow earthquakes last for hours or days.
This slow earthquake was detected by the analysis of coral reefs, or rather from ” microatolls »: Circular coral colonies, dead in the middle but alive at the ends. Those seen along the coast of Sumatra retain traces of changes in sea level around them (corals cannot grow when exposed to air) between 1738 and 1861, and these traces, according to the researchers, reveal the impact of the spread of this earthquake over 32 years.
Until now, the earthquake of 1861 has been interpreted as the result of a sudden rupture in the fault. But this study It can generate interest For a more detailed analysis of the areas where the tectonic plates are “rubbing”, looking for warning signs of a more serious event …
