Thermistor Array 2013

The thermistor array connected to the computer and power supply.

This medium powered junction-box (MJ03B) in the ASHES hydrothermal field was installed during the VISIONS'13 expedition. The titanium cylinder inside the frame hosts the power converters, data ports, and communication capabilities to shore via the Primary Nodes.

A 4.3 km cable extends from this J-Box across the caldera to PN3B, where it awaits future connection. MJ03B was installed as a 'subnet' during VISIONS'13 - two short-period seismometers are now connected to it via a 50 m and 1.2 km extension cable, respectively. A also host a cabled 3D thermistor array (a test instrument is shown in this image - triangular shaped frame with blue cables) was also deployed for testing. MJ03B, and all cables and connected sensors were fully tested during VISIONS'13, and are fully functional. During the several hour test period, several earthquakes were detected. 

During VISIONS '13 ROPOS dive 1636, a battery-powered version of the thermistor array was deployed and successfully tested at a small diffuse flow site at the base of the hydrothermal chimney called Mushroom in the ASHES vent field at the summit of Axial Volcano. This battery-powered version of the thermistor array will be deployed for a 1-year test as part of the first subnet* installed at ASHES.

The thermistor array is unusual in that most instruments designed for the cabled observatory are not capable of being powered by batteries alone. The 2013 deployment of the battery-powered thermistor array clearly illustrates the advantages of cabled instrumentation: the battery-powered instrument makes measurements only once every 10 minutes and that data will become available only upon recovery one year later, in 2014. By contrast, the cabled unit to be deployed in 2014 will make measurements every 5 seconds, and that data will be available nearly instantaneously via the Internet.

*This subnet includes the thermistor array, a 4-km cable extending from near Primary Node 3B and connected to the Medium powered J-Box (MJ03B) within the field.This J-Box includes connections to a 1.3 km extension cable across the caldera connected to a short-period seismometer and a 50 m extension cable with another short-period seismometer.

Overview of Thermistor Array