I know about mud and I know about volcanoes, but what is this "mud-spewing volcano"?

In 2011, on Russia's Sakhalin Island, a photographer took a very magical photo - the giant eye.

At first glance, you might really think you have discovered the "eye" of an ancient giant, but the "weird" thing is that this "giant eye" doesn't seem to blink, it just stares straight at the sky, and from the radiating "bloodshot" around the eyeball, you can vaguely see that... is it overusing its eyes?

Seriously, this mysterious "giant eye" is actually not the eye of an ancient giant, its true identity is a mud volcano.

The shape is quite strange just by looking at it, but in fact, this "giant eye" mud volcano is really an outlier, because ordinary mud volcanoes do not have such a "weird" momentum.

Ordinary mud volcano

When you get closer, you will find that most mud volcanoes look like a slightly larger mud pile, and their shapes vary, such as cone, egg tart, or flat pancake.

It will also produce various bubbles and patterns, and sometimes make a "gurgling" sound, as if the earth is breathing.

But what's so special about mud volcanoes? Of course, it's the mud they spray.

Because mud volcanoes contain a large amount of natural gas hydrates during their formation process, unlike real volcanoes whose ejecta are underground magma, the material erupted by mud volcanoes is mainly mud, and it is mixed with many gases, the highest content of which is methane, and there are small amounts of nitrogen and carbon dioxide.

However, there is one situation in which mud volcanoes will not spew out flammable gases such as methane. That is when there is a real volcano near the mud volcano. At this time, the mud volcano will only spew out non-flammable gases such as helium. Only mud volcanoes that exist alone will spew out mud containing a large amount of methane gas. Perhaps there is a saying in volcanoes that "when there is no tiger in the mountain, the monkey will be king"?

So how did this unique geological landscape form?

Mud volcanoes are generally formed in subduction zones and orogenic belts, and are also common near oil deposits. Therefore, a mud volcano may be accidentally created during oil exploration.

The formation of mud volcanoes is closely related to mud diapir. Mud volcanoes usually develop in the bottom of lateral structural basins with fast sedimentation rates. When the sedimentation rate of local strata obviously exceeds the discharge rate of fluids, the water filling the pores of the rocks cannot be discharged in time, which gradually generates strong pressure.

Once the formation pressure exceeds the pressure of the rock layer above, the high-pressure mud and various gas fluids deep underground will be transported to the surface through high-permeability channels such as faults, and then sprayed out without any worries, and accumulated on the surface into conical or circular sediments, which are mud volcanoes.

Distribution of mud volcanoes

Mud volcanoes have a characteristic: they always appear in groups (really "monkey groups"), often with dozens to hundreds of them in one area. If you find a mud volcano in an area, it is very likely that you can find a few more nearby.

Currently, there are mud volcanoes in 27 oceans around the world, but due to the difficulty of marine exploration, geologists speculate that there may be 5,000 to 10,000 mud volcanoes that have not been discovered.

There are more than 40 areas on land, including the famous Yellowstone National Park in the United States, Makran in Iran, Taiwan and Xinjiang in China.

But the largest number of mud volcanoes is found in Azerbaijan, which is home to one-third of all known mud volcanoes, or about 400.

Although there are many of them, the largest known mud volcano in the world is the Sidoarjo Mudflow in Indonesia. Since Indonesia is located in one of the most active subduction zones, there are many volcanic eruptions and mud volcano activities here.

The mud volcano has been erupting since May 2006. In its most serious eruption, it spewed large amounts of mud into a rural area within a radius of 4 square kilometers, killing 14 people and displacing 25,000 people.

However, only a few of these giant mud volcanoes are "naughty". Most of them are very well behaved. Moreover, they are not only a unique natural landscape and geological phenomenon, they also have many functions.

Since the dynamic accumulation process of natural gas hydrates is affected by the development stage of mud diapirs, mud volcanoes also bring us rich oil and gas resources.

In addition, mud volcanoes also nourish many organisms. Since the eruption materials of submarine mud volcanoes are rich in methane or sulfide, this provides sufficient energy for the surrounding chemoautotrophic microorganisms.

In addition, the study of mud volcanoes is also very necessary, and its importance is mainly reflected in the following aspects:

① Mud volcanoes are an important pathway for natural methane to enter the atmosphere and hydrosphere from the lithosphere;

② The rock debris ejected by mud volcanoes belongs to the shallow layer of the earth's surface. By studying it, we can gain a deeper understanding of the shallow layer of the earth;

③As mentioned above, mud volcanoes often appear in oil and gas belts. If you want to explore for oil, mud volcanoes may affect drilling, pipeline design and installation, so be prepared;

④ The natural gas hydrate in mud volcanoes is an important potential energy substance;

Therefore, the study of mud volcanoes is of great significance to the study of geological structure, oil and gas exploration, geological disasters, global climate change and lithosphere.