Scientists often have trouble getting enough sensors deployed in open water to obtain seismic readings. To solve this problem, researchers developed the MERMAID sensor. 

Mobile Earthquake Recording in Marine Areas by Independent Divers, or MERMAIDs for short, are floating seismometers, developed by Princeton geoscientist Frederik Simons, that can detect earthquake deep under the ocean and transmit seismic data real time.

Simons teamed with Guust Nolet, George J. Magee Professor of Geoscience and Geological Engineering, Emeritus, 15 years ago to build a robot with a hydrophone that can work undersea and pick up sounds to identify earthquakes deep inside the ocean. This device was to help seismologists scan the planet's core.

Today, Simons and Nolet, along with a team of international scientists, have published detailed findings obtained by their seismic floating devices in Scientific Reports. 

MERMAIDs Uncover Secrets Buried In Galapagos Island

MERMAIDs can travel up to 3 miles per day and go 1,500 meters below the ocean surface. Upon detecting the earthquake, the device scrambles back to the surface within 95 minutes, locates the earthquake's position, and sends seismic data via satellite.

Nine MERMAIDs navigated the oceans freely for two years around Galapagos and made seismic information available that was previously blank.

"Imagine a radiologist forced to work with a CAT scanner that is missing two-thirds of its necessary sensors," said Simons. "Two-thirds is the fraction of the Earth that is covered by oceans and therefore lacking seismic recording stations. Such is the situation faced by seismologists attempting to sharpen their images of the inside of our planet."

Unraveling The Mystery Of Earth's Core

MERMAIDs have helped the scientists find that the volcanoes on Galapagos are fed by a source buried 1,200 miles below the ocean surface and is connected to the surface volcanoes via a narrow conduit that brings the hot rock to the surface. This phenomenon is also known as mantle plumes.

The mantle plumes were proposed in 1971, and since then, their existence has been confirmed. However, their seismic activity was largely a mystery because of their presence in oceans far away from the seismic stations.

However, a network of oceanic seismometers helped geophysicists reach one of the blank areas on the geologic map and unravel the long-lasting mystery about how Earth has maintained constant temperatures for over 4.5 billion years.

Nolet hints that this high-temperature mantle plume may have a role to play in allowing Earth to maintain its core temperature.