Water Damage
Your homeowner's insurance might cover it, but be sure to check the subductible.
Your homeowner's insurance might cover it, but be sure to check the subductible.
This comic is the second in a series about absurd results of home inspections. The first, 3037: Radon came out less than two months before this one. Cueball is once again getting his home inspected by Ponytail, using the exact same device as in the first comic and also making the same introductory comment: "Oof. I was afraid of that." This time, she alerts Cueball about water damage, normally caused by leaky pipes or roofs. Water damage is hazardous to homes due to its ability to instigate mold and have negative impacts on structural stability of the home. Instead of his home suffering from water damage, Ponytail claims that the crust under Cueball's home suffers from water damage. The Earth's crust typically contains water; she could be referring to erosion, which is one cause of subsidence and even sinkholes, a concern to homeowners, but it soon becomes clear that she has different effects in mind.
Upon further investigation, Ponytail discovers that Cueball's home is near a subduction zone — a place where two tectonic plates meet, with one pushing beneath the other and descending deep into the Earth. This leads to the formation of magma as the descending plate heats up. The subducted material includes water in the form of hydrated minerals as well as liquid water, originally from seawater and seabed sediments drawn into the subducting fault. This moisture is forced out of the medium it is transported in and acts to lower the melting point of the adjacent rock, relative to what it would otherwise be, allowing magma to form more easily above the subduction interface. The magma can then force its way to the surface to form volcanoes, as Ponytail alludes to. However, there is nothing that Cueball can actually do about this supposed problem.[citation needed]
The solution given is similarly colossal in scale. Ponytail suggests "lithospheric dehumidifiers" as a solution, which would presumably dry out the Earth's crust, but this is not realistically possible. In waterlogged ground, continuous flight augering or the injection of grouting can assist in isolating the foundations from the surrounding water table. However, this has little use below the pedosphere and near-surface rock, such as down to the base of the upper plate involved in the subduction (well below the Mohorovičić discontinuity, tens of kilometers down). In addition, by drying out the crust, they might cause further subsidence and present additional hazards to the home. Massive lithospheric dehumidifiers would probably make the HOA upset, and possibly local governments. Like in 3037: Radon, this treats the Earth itself as if it is part of Cueball's property.
An example of an area with many volcanoes caused by subduction is the Ring of Fire along the coasts of the Pacific Ocean. In the contiguous 48 states, the Cascade Volcanoes of the Pacific Northwest are the result of this type of subduction. Subduction has been the topic of a few comics, see other examples in the explanation for the recent comic 3021: Seismologists that mentions it in the title text.
The title text is a pun making a portmanteau of subduction, explained above, and the deductible, the amount an insurance policy requires you to pay before it starts to contribute to the cost of the losses or expenses it covers. The title text may also be a critique of the homeowners insurance crisis in the United States at the time of the comic's posting.