China's 1st airborne electromagnetic detection system completes geological survey

China has successfully completed a high-altitude geological survey using its first helicopter airborne electromagnetic detection system, designed by the Aerospace Information Research Institute under the Chinese Academy of Sciences.

The system integrates key technologies such as high-sensitivity magnetic field sensors, wide-dynamic signal reception, and a stable airborne pod platform. It enables precise mapping of underground faults, fractures, groundwater, and mineral resources while identifying potential geological hazards.

During the two-month survey, research teams operated in extreme high-altitude and frigid conditions, conducting over 30 flight missions and covering more than 5,000 kilometers.

The system achieved a maximum detection depth of over 3,000 meters, providing critical data for the planning and construction of major national projects.

The airborne electromagnetic method (AEM) provides a rapid assessment of geological conditions as they relate to electrical conductivity or electrical resistivity. AEM uses a specialized transmitter to drive a time-varying current into a transmitter loop on an airborne platform. The transmitter loop generates an EM wave that propagates into the subsurface. As this energy encounters different subsurface layers or materials, it induces eddy currents that generate secondary EM fields. Secondary EM fields are detected by a receiver loop or magnetic antenna as the induced energy diffuses into the ground. The rate of diffusion indicates the resistivity of the subsurface materials.

Experts said that the system can play a vital role in supporting resource exploration and major infrastructure development.

China's 1st airborne electromagnetic detection system completes geological survey

China's foreign exchange reserves stood at 3.3421 trillion U.S. dollars at the end of March 2026, down 85.7 billion dollars, or 2.5 percent, from the end of February, official data showed on Tuesday.

The State Administration of Foreign Exchange noted that in March, the U.S. dollar index rose, while prices of major global financial assets declined, influenced by the global macroeconomic environment, monetary policies of major economies, and market expectations.

The combined effects of exchange rate conversion and changes in asset prices led to a decrease in China's foreign exchange reserves during the month, the administration said.

China's economy registered steady and improving performance during the period, with new and higher-quality development momentum. Its steady performance provided solid support for keeping the scale of the country's foreign exchange reserves basically stable, according to the administration.

China's foreign exchange reserves decline in March