Advances in Geophysical Methods for Deep Resource Exploration and Urban Underground Space Development

Dear Colleagues,

The relentless growth of the global population and economy continues to drive an insatiable demand for mineral resources, energy, and urban infrastructure. This demand pushes exploration and development activities into increasingly challenging frontiers: deeper mineral deposits concealed under thick overburden, complex geological settings, and the expansive, three-dimensional realm of the urban subsurface. In this context, geophysical exploration has transitioned from a reconnaissance tool to an indispensable, high-resolution imaging technique, forming the critical backbone for strategic decision-making in both deep resource assessment and sustainable underground space utilization.

The scientific foundation of this importance lies in geophysics' unique ability to infer subsurface physical property distributions (e.g., density, magnetization, electrical conductivity, seismic velocity) non-invasively. Unlike direct methods such as drilling, which provide only point information at high cost, geophysical surveys offer spatially continuous, volumetric images of the Earth's interior. For deep-seated resource exploration, this capability is paramount. Orebodies at depths of one kilometer or more rarely present surface expressions. Integrated geophysical methods—such as magnetotellurics for mapping resistive geological structures, controlled-source electromagnetics for detecting conductive ore zones, and high-resolution seismic reflection for delineating stratigraphy and faults—are essential for reducing the enormous financial risk associated with deep drilling. They create a probabilistic geological model, effectively narrowing the target and guiding optimal drill-hole placement. Simultaneously, the development of urban underground space (for metros, utilities, caverns, and resilient infrastructure) presents a different set of challenges. Here, the priority shifts from resource discovery to risk mitigation and precise engineering. The subsurface in urban areas is a complex, often poorly documented labyrinth of natural geology (bedrock, faults, water tables) and anthropogenic clutter (foundations, tunnels, utilities, contamination). High-resolution near-surface geophysical techniques—including ground-penetrating radar, electrical resistivity tomography, and micro seismic monitoring—are vital for accurately mapping this heterogeneity. They are crucial for geohazard assessment (e.g., sinkhole collapse, fault activation), ensuring the stability of excavations, protecting existing infrastructure, and managing groundwater impacts. Therefore, research in advanced geophysical methods, particularly in data inversion, multi-physics integration (joint inversion), and improved sensing technologies, is of fundamental importance. Enhancements in resolution, depth of investigation, and interpretive accuracy directly translate into higher discovery rates for critical metals, increased safety and efficiency in underground construction, and a lower environmental footprint. This research area is not merely academic; it is a strategic enabler for resource security, urban sustainability, and resilient infrastructure development in the 21st century.

We are pleased to invite you to submit your work to this Special Issue, titled "Advances in Geophysical Methods for Deep Resource Exploration and Urban Underground Space Development." 

In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

• Advanced electromagnetic methods for mineral exploration, including time-domain (TDEM), frequency-domain (FDEM), and magnetotelluric (MT) techniques, with a focus on deep-target detection, 3D inversion, and data integration.
• High-resolution seismic methods for detailed subsurface imaging, encompassing reflection seismology, full-waveform inversion, and passive seismic monitoring applied to both resource exploration and engineering-scale projects.
• Joint inversion and multi-physics integration, covering theoretical advances, novel coupling strategies, and case studies that effectively combine seismic, electromagnetic, gravity, and magnetic data to generate robust earth models.
• Applications of near-surface geophysics in urban underground space development, including the use of ground-penetrating radar, electrical resistivity tomography, and microgravity for utility mapping, void detection, and geohazard assessment.

Prof. Dr. Benyu Su
Dr. Rujun Chen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• geophysical exploration
• deep mineral exploration
• urban underground space development
• electromagnetic methods
• high-resolution seismic imaging
• multi-physics joint inversion
• near-surface geophysics
• 3D geological modeling
• geohazard assessment
• subsurface characterization