6.1 Magnitude Earthquake Hits Bismarck Sea; Shallow Depth Raises Aftershock Fears* | World News

In the statement made by the National Center for Seismology (NCS), it was stated that a 6.1 magnitude earthquake shook the Bismarck Sea on Tuesday.

The fact that the earthquake occurred at a shallow depth of 10 kilometers made it susceptible to aftershocks.

NCS said in a post about

Shallow earthquakes are generally more dangerous than deep earthquakes. This is because seismic waves from shallow earthquakes have a shorter distance to reach the surface, resulting in stronger ground shaking and potentially more damage to structures and more casualties.

The Australia-Pacific plate boundary is more than 4000 km long on its northern edge, from the Sunda (Java) trough in the west to the Solomon Islands in the east.

The eastern section is over 2,300 km long and extends from the northeast of the Australian continent and the Coral Sea westward to intersect with the eastern coast of Papua New Guinea. The boundary is dominated by a general northward subduction of the Australian plate, according to the USGS.

Along the southern Solomons trench, the Australian plate converges east-northeastward with the Pacific plate at a rate of approximately 95 mm per year. Seismicity along the trench is predominantly associated with subduction tectonics, and large earthquakes are common: there have been 13 M7.5+ earthquakes recorded since 1900.

On April 1, 2007, an M8.1 interplate megathrust earthquake occurred at the western edge of the trench, generating a tsunami and killing at least 40 people. This was the third M8.1 megathrust event associated with this subduction zone in the past century; the other two occurred in 1939 and 1977.

Further east, in the New Britain trough, relative motions of several microplates bordering the Australia-Pacific margin, including north-south oriented seafloor spreading in the Woodlark Basin south of the Solomon Islands, drive a generally northward subduction of the Australian-bound lithosphere beneath the Pacific-bound lithosphere.

Most major and major earthquakes in eastern New Guinea are related to this subduction; such earthquakes are particularly concentrated at the crest of the trench in southern New Ireland. According to the USGS, 33 M7.5+ earthquakes have been recorded since 1900, including three shallow thrust fault M8.1 events in 1906, 1919 and 2007.