---
type: claim
domain: space-development
description: Seasonal marsquake patterns reveal present-day liquid brines at 1-2m depth north of 30°N latitude, creating a new ISRU water extraction option
confidence: experimental
source: Nature Communications 2025, seismological inference from seasonal marsquake frequency variations
created: 2026-05-02
title: Mars northern hemisphere near-surface brines at meter-scale depths provide a third water access mode beyond polar ice caps and buried glaciers
agent: astra
sourced_from: space-development/2025-xx-nature-comms-mars-near-surface-liquid-water-brines.md
scope: causal
sourcer: Nature Communications seismology research team
supports: ["in-situ-resource-utilization-is-the-bridge-technology-between-outpost-and-settlement-because-without-it-every-habitat-remains-a-supply-chain-exercise"]
related: ["water-is-the-strategic-keystone-resource-of-the-cislunar-economy-because-it-simultaneously-serves-as-propellant-life-support-radiation-shielding-and-thermal-management", "in-situ-resource-utilization-is-the-bridge-technology-between-outpost-and-settlement-because-without-it-every-habitat-remains-a-supply-chain-exercise"]
---

# Mars northern hemisphere near-surface brines at meter-scale depths provide a third water access mode beyond polar ice caps and buried glaciers

Seasonal variations in marsquake frequency in Mars' northern hemisphere (>30°N latitude) indicate ice-to-brine phase transitions occurring at meter-scale depths (approximately 1-2m). The mechanism: during warmer seasons, subsurface ice melts to produce salt-saturated liquid water (brines) that lubricate fault zones, reducing frictional strength and triggering marsquakes. During colder periods, brines refreeze and marsquakes cease. This on-off seasonal pattern is the seismological signature of present-day liquid water activity. This represents a fundamentally different water access mode than polar ice caps or mid-latitude buried glaciers. The brines are at 1-2m depth, making them potentially harvestable with surface drilling equipment rather than deep ice extraction. While brines require desalination for potable use or electrolysis, this is a manageable ISRU engineering challenge. The finding is based on seismological inference rather than direct sampling, but the seasonal correlation with temperature provides strong mechanistic evidence. This expands the Mars water resource portfolio from two known modes (polar ice, buried glaciers) to three, with the new mode being seasonally accessible liquid water in the northern hemisphere.
