Numerous submarine landslides detected in the Gulf of Mexico

In a new study, scientists have identified 85, previously unknown, submarine landslides in the Gulf of Mexico that occurred in a 7-year period (from 2008 to 2015).

The results of the study have been recently published in Geophysical Research Letters.

Submarine landslides occur at the seafloor as a result of gravitational forces, seismic loads, high pore-water pressures and/or weakened ground materials. Compared to typical landslides on the earth's surface, they can be much larger and move greater distances. Nonetheless, according to the study, their failure mechanism and behavior are not yet fully understood.

The impact of underwater slides can be significant. It may range from the devastation of submarine infrastructure (wires or pipes) to the destabilization of oil platforms or even to triggering of a tsunami. In 2004, an oil platform sank off the coast of Louisiana due to a mudslide. The accident resulted in one the biggest leakages in the United States history.

The seafloor of the Gulf of Mexico is particularly prone to landsliding as it constantly receives huge amounts of river sediments that create a steep underwater topography.

According to Wenyuan Fan, lead author of the study and an Assistant Professor in the Department of Earth, Ocean and Atmospheric Science at Florida State University, the underwater landslides identified at the Gulf of Mexico pose a severe threat to coastal regions.

Prof. Fan and his scientific team, utilized the USArray, a large network of seismographs in the United States. The team did not search for seismic shocks but, rather, they tried to identify events that could trigger a seismograph such as a landslide. The researchers detected signals from the Gulf of Mexico where few earthquakes occur. By analyzing the data, they concluded that the signals derived from underwater ground displacements. “There are few active faults in the Gulf, and the seismicity is scarce in the region. This puzzled me and concerned me because we live close to the Gulf. With the question and the concern, I looked into the details of these seismic sources and eventually concluded that they are likely to be submarine landslides,” Prof. Fan, said.

Out of the 85 underwater slides that the team identified, 10 occurred without an apparent triggering factor. However, the additional 75 were triggered by distant and relatively small earthquakes (most of them occurred along the Pacific and North American tectonic plate boundary), a fact that surprised the researchers. “I didn’t expect landslides would be that prevalent in the Gulf of Mexico. And I didn’t know landslides are so susceptible to dynamic triggering caused by passing seismic waves. I constantly tried to prove myself wrong,” Prof. Fan, stated.

The method developed to detect the submarine landslides may be used in the future to establish a warning system when a slide occurs. Such a system would require the installation of seismographs on the seafloor and, potentially, it could help prevent a disaster such as an oil spillage.