As I started digging into the ludicrous idea that HAARP can be used to create Earthquakes, I found the rabbit hole runs very deep, and a good researcher who relishes finding interconnected scientific history will absolutely have a riot digging into these holes. Here are some miscellaneous findings so far:

Some research papers that are pertinent to the possibility of using HAARP and other means that utilize high-power high-frequency transmitters to "excite the ionosphere" for the ostensible purpose of "understanding what happens due to natural stimulation by sun" (I mean, you would just study the natural stimulation of son, wouldn't you?)

This 1996 paper titled Ionospheric precursors to earthquakes has this introduction:

For the last decade in a number of satellite experiments new
phenomena which occur prior to earthquakes were discovered in the ionosphere and the magnetosphere.

...

The processes listed above were observed from space or
with ground-based instruments before earthquakes, preceding them by hours, days, or weeks depending on the type of
the phenomena. 

Another team lead by Pulinets has also published extensively on the correlation between changes in Ionosphere and Earthquakes.

Correlation analysis technique revealing ionospheric precursors of earthquakes

Ionospheric precursors of earthquakes and Global Electric Circuit

There was a calculation done in a prior dig post where we calculated that the 3.6 Megawatt HAARP facility in Alaska can generate enough power equal to the power of the Turkey Earthquake (6000 Tsar Bombs) in 36 hours! The Alaskan HAARP is, apparently, just a toy factory. There are other similar facilities around the world, some with wattage thats hundred times that of the Alaskan one.

There is evidence that this technology was being developed long back and was originally intended for mass mind control. Here is an excerpt from a book Between Two Ages written in 1969 by none other than the architect of forever wars Zbigniew Brzezinski

In addition, it may be possible—and tempting—to exploit for strategic­political purposes the fruits of research on the brain and on human behavior. Gordon J. F. MacDonald, a geophysicist specializing in problems of warfare, has written that accurately timed, artificially excited electronic strokes "could lead to a pattern of 
oscillations that produce relatively high power levels over certain regions of the earth. ... 

In this way, one could develop a system that would seriously impair the brain performance of very large populations in selected regions over an extended period. . . . No matter how deeply disturbing the thought of using the environment to 
manipulate behavior for national advantages to some, the technology permitting such use will very probably develop within the next few decades."

Now you might ask, who is this Gordon MacDonald that ZB referenced, and why is a geophysicist talking about using "artificially excited electronic strokes" to mass control minds of people. This is where the story gets interesting. MacDonald did extensive research into Plate Tectonics when the theory of continental drift started becoming popular amongst the scientists.

His memoirs by Walter Munk, the guy he worked on Tectonics with

Here is the interesting part - he actually argued that geophysical constraints based on the finite strength of elastic material makes it hard to believe the Plate Tectonics theory and eventually quit the field when he was shunned by the rest of the scientists.

In the early 1960s, new observations and interpretations of the sea floor data led to the theory of plate tectonics. According to this theory, low-intensity long-term stresses
drive the horizontal motion of the plates. I argued in two
papers that the large-scale difference between continents
and oceans . . . extended to several hundred miles’ depth
. . . and that the mantle possesses a finite strength, as argued by Harold Jeffreys. . . . My insistence that geophysical
constraints must be discussed led many participants . . . to
dismiss me as a troglodyte who was slowing the convergence
of thought that was later to be labeled either as a revolution or a paradigm shift.”

So the geophysist who is an expert in the Plate Tectonics and argued against the popular theory now attributed to earthquakes, was also working on high energy oscillations similar to HAARP, that could be used for mass mind control!

Incidentally, the same Walter Munk who worked with MacDonald on plate tectonics, had an idea to bore into the earth all the way to the Mantle, as reported in this Nature Article

The idea came primarily from Harry Hess, one of the founding fathers of the theory of plate tectonics, and Walter Munk, who pioneered studies of how winds drive ocean currents and explained why one side of the Moon is locked towards Earth. Frustrated by what they saw as a stream of worthy yet pedestrian research proposals in their field, they sought to undertake something more ambitious and innovative.

At a wine breakfast at Munk's home in La Jolla, California, on a Saturday morning in April 1957, they came up with Project Mohole, a scheme to drill, for the first time, right through Earth's crust and into the upper mantle.