Kuliah Lapangan Geofisika 2020 - Metode Geolistrik

Summary

This video script details a geophysical demonstration using the geoelectrical method to understand subsurface rock layer properties. It showcases the use of SuperSting X8Aij equipment from Ide-Ide Spensgo Sign for 1D and 2D resistivity measurements. The script explains the setup, including electrodes and cables, and the process of data acquisition, including preparing the survey design, setting up in the field, and connecting the main unit. It also covers potential issues like contact resistance and the importance of data processing for resistivity interpretation.

Takeaways

• ⚡ Geoelectric method is used to determine the electrical properties of rock layers beneath the surface by injecting electric current into the ground.
• 🛠️ The demonstration focuses on the DC resistivity method using a SuperSting X8 instrument, produced by a geophysical survey equipment company.
• 🔌 The system is designed with 28 electrodes and uses four cables, allowing for both 1D and 2D measurements depending on the configuration.
• 📏 The maximum distance between electrodes is 35 meters, enabling measurements of up to 900+ meters with proper setup.
• 🔋 The power supply involves a 12-volt battery, with the option to use two for increased power during measurements.
• 💻 Command files are created using specific software to manage the data acquisition process and configure the system for measurement.
• 📊 The configuration includes various setups like Schlumberger and Wenner arrays, allowing for different types of resistivity measurements.
• ⚙️ After the command file is created, it is uploaded to the SuperSting unit for field data acquisition, starting with electrode positioning and connection testing.
• 🛡️ Warnings and safety signs are placed around the electrodes during installation to prevent interference with measurements.
• 📈 After data acquisition, the collected data is processed and converted into formats for further analysis, allowing for interpolation and inversion to generate resistivity profiles.

Q & A

What is the purpose of the geoelectrical method described in the script?

The geoelectrical method aims to determine the electrical properties of subsurface rock layers by injecting electrical currents into the ground.

What equipment is used for the geoelectrical survey in the video?

The equipment used includes a SuperSting X8 system, 28 electrodes, and other supporting items like a switch box, 12V power supply, and connecting cables.

What is the configuration of the cables and electrodes during the geoelectrical survey?

There are four cables, each with 7 electrodes, making a total of 28 electrodes. These cables are carefully connected to ensure proper measurement, with the electrodes spaced 35 meters apart.

How is the SuperSting X8 powered during the survey?

The SuperSting X8 is powered using a 12V battery, with the option to use two batteries simultaneously to increase power for measurements.

What is the role of the 'command file' mentioned in the script?

The 'command file' is used to instruct the SuperSting system on how to perform data acquisition. It is created and configured before the fieldwork to ensure correct data collection.

How does the system handle faulty connections during the survey?

The system checks the contact resistance of the electrodes, and if a faulty connection is detected, the problematic electrode can be skipped to ensure the survey continues without errors.

What steps are taken before starting the actual data acquisition in the field?

Before data acquisition, the team ensures proper alignment of the survey path with the designed survey layout, cleans the survey area, and installs the electrodes and cables.

What is the purpose of the 'warning signs' mentioned during electrode installation?

The warning signs, usually yellow flags, serve as indicators for people passing by and also help identify electrode locations during the installation process.

What types of resistivity configurations are used in this geoelectrical survey?

The survey uses two main configurations: the Wenner configuration and the Schlumberger configuration, both of which are used to measure the potential difference across electrodes.

How is the collected data processed after fieldwork?

The data collected from the SuperSting X8 is saved on the main unit and then transferred to a laptop for processing using specialized software. The data is converted into formats like TTG or Sting for further analysis, including interpolation and inversion modeling.