Has That Oilfield Caused My Earthquake?

“Some six months have passed since the magnitude (Mw) 6.7 earthquake struck Los Angeles County, with an epicenter close to the coast in Long Beach. Total economic loss estimates are more than $30 billion.  Among the affected homeowners, the earthquake insurance take-up rates were pitifully low – around 14 percent. And even then, the punitive deductibles contained in their policies means that homeowners may only recover 20 percent of their repair bills.  So, there is a lot of uninsured loss looking for compensation. Now there are billboards with pictures of smiling lawyers inviting disgruntled homeowners to become part of class action lawsuits, directed at several oilfield operators located close to the fault. For there is enough of an argument to suggest that this earthquake was triggered by human activities.”   

This is not a wild hypothesis with little chance of establishing liability, or the lawyers would not be investing in the opportunity. There are currently three thousand active oil wells in Los Angeles County. There is even an oil derrick in the grounds of Beverly Hills High School. Los Angeles County is second only to its northerly neighbor Kern County in terms of current levels of oil production in California.  In 2013, the U.S. Geological Survey (USGS) estimated there were 900 million barrels of oil still to be extracted from the coastal Wilmington Field which extends for around six miles (10 km) around Long Beach, from Carson to the Belmont Shore.

Beverly Hills High School Picture Credit: Sarah Craig for Faces of Fracking / FLICKR

Beverly Hills High School   Picture Credit: Sarah Craig for Faces of Fracking / FLICKR

However, the Los Angeles oil boom was back in the 1920s when most of the large fields were first discovered. Two seismologists at the USGS have now searched back through the records of earthquakes and oil field production – and arrived at a startling conclusion. Many of the earthquakes during this period appear to have been triggered by neighboring oil field production.

The Mw4.9 earthquake of June 22, 1920 had a shallow source that caused significant damage in a small area just a mile to the west of Inglewood. Local exploration wells releasing oil and gas pressures had been drilled at this location in the months before the earthquake.

A Mw4.3 earthquake in July 1929 at Whittier, some four miles (6 km) southwest of downtown Los Angeles, had a source close to the Santa Fe Springs oil field; one of the top producers through the 1920s, a field which had been drilled deeper and had a production boom in the months leading up to the earthquake.

A Mw5 earthquake occurred close to Santa Monica on August 31, 1930, in the vicinity of the Playa del Rey oilfield at Venice, California, a field first identified in December 1929 with production ramping up to four million barrels over the second half of 1930.

The epicenter of the Mw6.4 1933 Long Beach earthquake, on the Newport-Inglewood Fault was in the footprint of the Huntingdon Beach oilfield at the southern end of this 47 mile-long (75 km) fault.

As for a mechanism – the Groningen gas field in the Netherlands, shows how earthquakes can be triggered simply by the extraction of oil and gas, as reductions in load and compaction cause faults to break.

More Deep Waste Water Disposal Wells in California than Oklahoma

Today many of the Los Angeles oilfields are being managed through secondary recovery – pumping water into the reservoir to flush out the oil. In which case, we have an additional potential mechanism to generate earthquakes – raising deep fluid pressures – as currently experienced in Oklahoma. And Oklahoma is not even the number one U.S. state for deep waste water disposal. Between 2010 and 2013 there were 9,900 active deep waste water disposal wells in California relative to 8,600 in Oklahoma. And the California wells tend to be deeper.

More than 75 percent of the state’s oil production and more than 80 percent of all injection wells are in Kern County, central California, which happens to be close to the largest earthquake in the region over the past century on the White Wolf Fault: Mw7.3 in 1952. In 2005, there was an abrupt increase in the rates of waste water injection close to the White Wolf Fault, which was followed by an unprecedented swarm of four earthquakes over Magnitude 4 on the same day in September 2005. The injection and the seismicity have been linked in a research paper by Caltech and University of Southern California seismologists published in 2016. One neighboring well, delivering 57,000 cubic meters of waste water each month, was started just five months before the earthquake swarm broke out. The seismologists found a smoking gun, a pattern of smaller shocks migrating from the site of the well to the location of the earthquake cluster.

To summarize – we know that raising fluid pressures at depth can cause earthquakes, as is the case in Oklahoma, and also in Kern County, CA. We know there is circumstantial evidence for a connection between specific damaging earthquakes and oil extraction in southern California in the 1920s and 1930s. According to the location of the next major earthquake in southern or central California, there is a reasonable probability there will be an actively managed oilfield or waste water well in the vicinity.

Whoever is holding the liability cover for that operator may need some deep pockets.

Chief Research Officer, RMS
Robert Muir-Wood works to enhance approaches to natural catastrophe modeling, identify models for new areas of risk, and explore expanded applications for catastrophe modeling. Recently, he has been focusing on identifying the potential locations and consequences of magnitude 9 earthquakes worldwide. In 2012, as part of Mexico's presidency of the G20, he helped promote government usage of catastrophe models for managing national disaster risks. Robert has more than 20 years of experience developing probabilistic catastrophe models. He was lead author for the 2007 IPCC 4th Assessment Report and 2011 IPCC Special Report on Extremes, is a member of the Climate Risk and Insurance Working Group for the Geneva Association, and is vice-chair of the OECD panel on the Financial Consequences of Large Scale Catastrophes. He is the author of six books, as well as numerous papers and articles in scientific and industry publications. He holds a degree in natural sciences and a PhD in Earth sciences, both from Cambridge University.

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