Geophysical Surveys Explained: Gravity, Magnetic, Seismic, and IP Methods for Pakistan's Mining Sector

A geophysical survey measures physical properties of the ground — density, magnetism, electrical conductivity — to find what's buried without digging. For Pakistan's mining sector, the four methods that matter most are gravity, magnetic, seismic, and induced polarization (IP). Each one answers a different question, and picking the wrong one wastes both money and drilling budget.

Here's the thing most mine owners don't realize. You don't run all four. You run the one that matches your target mineral and geology. Chromite behaves nothing like copper underground, and the survey you'd use for each is completely different.

Let me walk through what each method actually does.

What does a magnetic survey detect in mineral exploration?

A magnetic survey maps variations in the Earth's magnetic field caused by rocks with different magnetic properties. Simple idea. Some minerals carry magnetite or other magnetic material, and they distort the local field in ways an instrument can pick up.

This is the workhorse of geophysical survey mining. It's fast, it's relatively cheap, and it covers big areas. In Pakistan, magnetic surveys are useful for chromite (like the deposits around Muslim Bagh and Waziristan), iron ore, and for mapping the broad geological structure — faults, contacts, intrusions — that guides where deposits sit.

You can fly it. Airborne magnetic surveys cover hundreds of square kilometers in days. Or you can walk it on the ground for finer detail over a smaller block.

What it won't tell you. The exact depth or grade of what you've found. It shows you an anomaly. Something's down there. But you still need drilling or another method to confirm.

When should you use gravity surveys instead?

Gravity surveys measure tiny differences in the Earth's gravitational pull caused by rocks of different densities. Dense stuff — massive sulphides, chromite bodies, some ore deposits — pulls slightly harder. The instrument (a gravimeter) is sensitive enough to detect that.

Use gravity when density contrast is your best clue. Chromite is dense. Massive sulphide deposits are dense. If your target rock is much heavier than the surrounding ground, gravity works well.

But it's slow. Ground gravity surveys need careful station-by-station measurement, and you have to correct for elevation, latitude, and terrain — which in the mountains of Gilgit Baltistan or Balochistan is a real headache. The corrections matter enormously in rugged ground, and sloppy terrain correction gives you garbage results.

So. Gravity is precise but expensive per square kilometer. It shines as a follow-up over a target you've already narrowed down, not as a first-pass scan.

What is an IP survey and why does it matter for copper in Pakistan?

Induced polarization — IP — is the single most important geophysical method for copper exploration. And Pakistan's copper belt around Reko Diq, Chagai, and the wider Balochistan magmatic arc makes IP survey mining Pakistan a serious topic.

Here's how it works. You send an electrical current into the ground. Disseminated sulphide minerals (the kind you get in porphyry copper systems) hold onto electrical charge and release it slowly after the current stops. IP measures that "chargeability." High chargeability often means sulphides — which often means copper, sometimes gold.

That's why IP is so valuable. Porphyry copper deposits are usually low-grade sulphides spread through huge volumes of rock. You can't see them with the eye. Magnetic surveys might catch the associated alteration, but IP directly responds to the sulphides themselves.

IP is slower and more expensive than magnetics. You're laying out electrodes, moving cables, running current through the ground. It needs skilled crews. But for copper and porphyry-style gold, honestly, there's no substitute among the standard geophysical methods mineral exploration relies on.

One caveat. IP can give false positives. Graphite and clay also chargeup. So you interpret IP alongside geology and other data — never on its own.

Where do seismic surveys fit in mining?

Seismic surveys send sound waves (or vibrations) into the ground and record how they bounce back off layers of different rock. This is the method the oil and gas industry lives on.

In hard-rock metal mining, seismic is used less often. It's expensive, and it's built for layered sedimentary basins, not the messy fractured rock where most metal deposits sit. But it has a place. Seismic is excellent for mapping deep structure, coal seams, and — increasingly — for deep mine planning where you need to know rock conditions before you commit to a shaft.

For most individual mine owners in Pakistan, seismic won't be your first call. Coal operators and large deep deposits are the main users.

Which geophysical method should you actually choose?

Here's a quick reference table to match method to target:

A sensible workflow for a geophysical survey Pakistan project usually goes wide-to-narrow:

• Start with regional data — satellite and airborne magnetics — to find broad anomalies
• Narrow down promising zones with detailed ground magnetic or gravity work
• Run IP over the most promising copper/sulphide targets
• Drill only where multiple datasets agree

That last point is where people burn money. Drilling on a single anomaly. Look, drilling is the most expensive step by far. Every method above exists to reduce how many holes you drill blind.

Where satellite work fits before you spend on ground crews

Ground geophysics is expensive and slow to mobilize — especially in remote parts of Balochistan and Gilgit Baltistan. That's the gap we work in at GeoMine AI. Before you pay a crew to haul gravimeters up a mountain, we use Sentinel-2, ASTER, SAR, and SRTM DEM data with AI to map alteration zones, structures, and mineral indicators from space.

We don't replace geophysical survey Pakistan crews. We tell you where to point them. Satellite intelligence narrows a 500 km² license down to a handful of priority zones, so your IP or gravity budget goes where it counts.

I own 15 mines in Gilgit Baltistan myself, so I've felt the pain of spending on the wrong ground. That's the whole reason geomines exists.

If you've got a license or a claim and you're deciding which geophysical method to commission, send us the coordinates first. We'll generate a satellite report showing the most promising zones — then you commission the right ground survey over the right spot instead of guessing. Start at https://geomines.org.