In the Southern Basin in Trinidad, there are many mud volcanoes that litter the landscape.

"Mud volcano" is a misnomer, as it is not a conventional volcano that spews molten lava.

These are natural onshore and offshore surface expulsions of semi-liquid mud and gas.

One such example of a mud volcano is the Piparo mud volcano.

To many, the Piparo mud volcano is a exciting tourist attraction, to others a spiritual site and to a remaining few, a part of what they called home.

A major eruption on February 22, 1997 transformed a small muddy pool into the large main vent we see today (Figure 1) and resulted in damage to homes, leaving many homeless.

From that day forward, continuous activity at the site has led to many studies and frequent surveillance being carried out by UWI and other organisations.

[caption id="attachment_1030750" align="alignnone" width="1024"] Figure 4: The migration of mudflow(Figure courtesy GSTT) -[/caption]

ERT (electrical resistivity tomography) and DEM (digital elevation models), for example, are methods that were used to uncover the origin of the fluid, processes and activity of the mud volcano. The information received from this surveillance can be used to predict future eruptions and help warn nearby residents.

The mud volcano lies along the Naparima Hill thrust fault, along which mud is transported from great depth to the surface. This fault was formed by transpression that occurred between the Caribbean and South American plate around the mid-Miocene (around 12 million years ago).

This opened up a gateway for materials that were even older than this compressional event to be transported to the surface and seen at the site of the volcano today (Figure 2).

Although many are able to see the expulsion of mud at the surface, the subsurface expression of the volcano remains hidden.

ERT surveys can map out an image of the subsurface by measuring its resistivity or its ability to resist an electric current.

Different objects will carry different resistivities, allowing us to create a colour-coded image with the data that is collected. From this image we can identify any resistive objects.

DEM surveys on the other hand, work by using drone captured aerial images to create colour-coded elevation maps. These maps can be used to identify any topographical or surface changes over time.

[caption id="attachment_1030751" align="alignnone" width="1024"] Figure 5: Diagram showing changes in elevation over time(Figure courtesy GSTT) -[/caption]

For this study, datasets from the years 2018-2023 were used to track changes in the subsurface shape and topographic elevation through time.

The datasets have given insights into the nature of the mud volcano. It ejects mobile mud (clays and shales mixed with fresh water) (Figure 3) which eventually hardens when dried, creating a mound with the resistive values of the subsurface being indicative of this. The subsurface chamber of the mud volcano had an approximate volume of 176,493 cubic metres in January of 2023. For reference, tha