Man-made earthquakes are on the rise in the United States, but who is at fault? Some will blame climate change (also arguably induced by humans) while others will say human activity is responsible.

Regardless of the cause, there is no denying that earthquakes have made more of a rumble than usual in recent years. For example, from 1978 to 2008, Oklahoma averaged only two earthquakes over magnitude 3.0 per year, Nature World News previously reported. But midway through 2014, the state has already registered 230 quakes of that strength, surpassing California's record.

People are increasingly looking to hydraulic fracturing - or "fracking" as it's commonly called - as the culprit. Fracking is a technique designed to obtain gas and oil from shale rock, according to BBC News. The process involves drilling down into the earth's surface followed by injecting water, sand and chemicals at high pressure to release gas from the rocks. The wastewater is then injected into subsurface wells to avoid contaminating water sources.

In addition to Oklahoma, Texas, Arkansas and Ohio have also recently seen spikes in earthquakes near wastewater injection wells. It seems that the evidence is piling up and pointing to fracking more and more, although some remain skeptical.

"The Earth, and the science of how everything works, is so big," Oklahoma state representative Lewis Moore told Newsweek. "We are so minute. For us to think that we have so much to do with these things is almost ludicrous."

The History of Evading Blame

Trying to pin the blame on someone other than ourselves is nothing new. Humans used to believe good weather was a sign that the Gods were happy, while their disapproval resulted in natural phenomena like droughts, fires, or earthquakes.

In the second century AD, the Roman emperor Trajan and his people found themselves trying to dodge crumbling buildings as an earthquake shook the ancient city of Antioch. Trajan believed the spread of Christianity angered the Roman gods and so they sent the quake to retaliate against the townsfolk.

Fast forward to 1755 when a devastating quake hit Lisbon, Portugal - a disaster also blamed on religious differences between Christianity and Protestantism.

Even today, religion seems to be the easy scapegoat. According to The Advocate, Pat Robertson, a Southern Baptist minister, cited the 1994 San Fernando Valley earthquake - which killed 72 people - as God's way of showing his displeasure with gays and pro-choice activists.

Whether it's an act of God or forces of nature, earthquakes seem larger-than-life, so the prospect that we might play a role in them is difficult to comprehend.

"When you start thinking about it, you think, 'How can we as puny little humans do that?'" seismologist Cliff Frohlick of the University of Texas at Austin told Newsweek.

The Fracking Boom

A few years ago, many people thought the idea of fracking playing a role in increased incidents of earthquakes was laughable. After all, of the 10,000 injection wells in Texas, "only 20 or so have caused quakes," Frohlick said.

However, with global warming on the brain, experts are looking towards other renewable means of accessing fuels so as to reduce our carbon footprint. As a result, the fracking boom has soared to new heights.

According to a report by Environment America, as of 2013 fracking is ongoing in 17 states, with more than 80,000 wells drilled or permitted since 2005. And the oil and gas industry is continuing to expand, looking to build fracking sites in states like New York, California, and North Carolina, as well as in areas that provide drinking water to millions of Americans.

The intense drilling involved in such practices can lead to tremors, sparking earthquakes that are caused by a shift in Earth's tectonic plates at what is called the fault line.

"Induced seismicity is one of the primary challenges for expanded shale gas and unconventional hydrocarbon development. Our results provide insight into the process by which the earthquakes are induced and suggest that adherence to standard best practices may substantially reduce the risk of inducing seismicity," Katie Keranen at Cornell University, who was behind a recent study published in the journal Science, said in a press release.

"The best practices include avoiding wastewater disposal near major faults and the use of appropriate monitoring and mitigation strategies."

According to researchers, around 20 percent of the earthquakes in the central United States can be triggered by water disposal at just four of highest-volume disposal wells in Oklahoma. What's more, these disposal wells don't even have to be close by to induce an earthquake. Earthquakes can happen at distances over 30 kilometers (19 miles) from these wells - far behind existing criteria of five kilometers (3.1 miles) from the well to be diagnosed as a man-made earthquake.

Fracking does not just pose a risk of an earthquake, but has other environmental and public health implications, too. Environmental America's report says that the enormous volumes of wastewater produced by fracking - some 280 billion gallons in 2012 alone - often contains cancer-causing and even radioactive materials, and has contaminated drinking water in several states. In New Mexico alone, waste pits from oil and gas drilling has contaminated groundwater on more than 400 occasions.

The US Geological Survey (USGS), Nature World News reported, is now looking to include wastewater injection to estimate earthquake hazards given the rise in earthquake incidents.

Researchers cite two earthquakes from 2011 as examples: one in southern Colorado, at magnitude 5.3, and another in Oklahoma, at magnitude 5.7, both supposedly caused by wastewater injection from fracking. Although, lead researcher Justin Rubinstein and his team claim they aren't trying to determine whether recent earthquakes are natural or human-made, but are mainly trying to find ways to tell the difference.

"To some degree, it doesn't actually matter whether or not these earthquakes are induced," Rubinstein told The Christian Science Monitor. "The increased rate indicates there is an increase in hazard."

Scientists have yet to fully understand the mechanisms behind earthquakes, let alone how fracking plays a role, if indeed it does.

"We don't have a comprehensive understanding of what causes these quakes - near one well it happens, near another it doesn't," USGS seismologist Susan Hough admitted to Newsweek. "There's a lot more uncertainty with earthquakes and we're trying to communicate with imperfect knowledge."