# Precipitation induced by explosive volcanism on Mars and its implications for unexpected equatorial ice

## TL;DR

Explosive volcanic eruptions on early Mars may have delivered ice to equatorial regions, explaining unexpected ice deposits.

## Contribution

New simulations show explosive volcanism could repeatedly deliver ice to Mars' equator, independent of planetary tilt.

## Key findings

- Simulations show up to 5 meters of ice could be deposited in a single eruption event.
- Volcanic ice delivery could explain equatorial ice deposits without requiring high planetary tilt.
- Ice could persist if shielded by volcanic dust or sulfuric acid cooling.

## Abstract

Explosive volcanism occurred on Mars during its early history (Noachian–Hesperian; ~4.1–3.0 Ga). Because of Mars’ cold atmospheric temperatures, water released from explosive eruptions may precipitate as ice or ice-ash aggregates. This process may have supplied ice to equatorial regions, which contain high excess hydrogen and potential buried ice deposits. We simulate explosive volcanic eruptions using the Laboratoire de Météorologie Dynamique Generic Planetary Climate Model and find that up to ~5 meters of ice is delivered to the surface in only one high-magnitude eruptive event. This ice can persist for long periods if preserved by widespread cooling from volcanic sulfuric acid or by burial under dust or pyroclasts. Here we show that over time, explosive eruptions may have served as a recurring mechanism for delivering ice to the equator, explaining elevated ice content at low latitudes independent of obliquity.

New modeling shows that explosive volcanic eruptions on Mars could have repeatedly delivered ice to the equator, pointing to a volcanic origin for the mysterious excess hydrogen in the planet’s shallow equatorial surface.