California recorded 64 earthquakes in a single 24-hour period, more than any other state in the country, while the oil-producing regions of Texas registered 29 quakes during the same span. The contrast between the two states raises a pointed question: how much of the shaking in Texas traces back to the underground disposal of oilfield wastewater, and are regulators doing enough to reduce it? With California sitting atop the San Andreas Fault system and Texas sitting atop some of the most active injection wells in the nation, the daily earthquake tallies tell two very different stories about seismic risk.
Why 64 quakes in California and 29 in Texas demand different responses
California’s seismicity is driven by natural tectonic forces. The state straddles multiple active fault systems, and dozens of small quakes on any given day are routine. Texas, by contrast, was historically one of the quieter seismic states. The sharp rise in Texas earthquake activity over the past decade has been tied repeatedly to high-volume wastewater injection into deep disposal wells, a byproduct of oil and gas production. That connection is why the Railroad Commission of Texas, the state’s oil and gas regulator, now maintains designated seismic response areas where operators face restrictions or outright suspensions of injection permits when earthquakes occur near their wells.
The daily counts referenced in the headline come from the USGS Advanced National Seismic System Comprehensive Earthquake Catalog, known as ComCat, which compiles event parameters from contributing seismic networks across the country. ComCat applies preferred solutions after review, meaning reported counts can shift slightly as analysts refine location and magnitude data. The catalog is the standard federal reference for comparing seismic activity across states, but it does not distinguish between naturally occurring and human-triggered events in its raw tallies.
That distinction matters. A 29-quake day in Texas carries regulatory weight that a 64-quake day in California does not, precisely because many Texas events may be linked to industrial activity that state agencies have the authority to curtail. The Railroad Commission operates an underground injection program for Class II wells, requiring operators to file monthly reports of injection rates, volumes, and pressures. Those filings create a paper trail that, in theory, lets regulators correlate specific wells with nearby seismic clusters.
How Texas regulators changed their seismicity review process in 2024
The Railroad Commission updated its methodology for evaluating disposal permits against seismic data, with changes effective March 15, 2024, according to the commission’s seismicity review page. The update refined how regulators assess new and existing permits in areas with elevated earthquake risk. Before the update, critics argued that the commission’s review process lagged behind the pace of drilling and injection activity, leaving some wells operating at high volumes in seismically sensitive zones.
A reasonable hypothesis is that counties inside current Texas Seismic Response Areas should show a measurable drop in cataloged earthquakes per unit of injected volume after the March 2024 methodology update, compared with matched counties outside those areas. If the new review process is working as intended, the ratio of quakes to injection volume should decline where restrictions are tightest. Testing that hypothesis requires pairing the commission’s monthly injection data, available through its online reporting system, with ComCat event counts filtered by county and date range. The monthly reporting cadence means any signal would emerge over quarters, not days, and the publicly available data does not yet allow a clean before-and-after comparison at the individual well level.
Institutional monitoring adds another layer. The Bureau of Economic Geology at the University of Texas at Austin runs TexNet, a seismic monitoring network, and the Center for Injection and Seismicity Research, both of which supply data and analysis tied to oilfield operations. The state homeland security office also plays a coordination role in Texas’s seismic preparedness, particularly where earthquake risk intersects with critical infrastructure and emergency planning. Together, these agencies create a monitoring ecosystem that did not exist a decade ago, when Texas earthquake rates first began climbing.
Gaps in the data linking Texas quakes to specific wells
Several pieces of the puzzle are still missing. The daily earthquake counts that produced the 64-versus-29 comparison do not come with event-by-event UTC time bounds or focal mechanism details tied to individual Texas quakes. The USGS publishes focal mechanism data at the program level, but matching those solutions to specific disposal wells requires additional analysis that neither the USGS nor the Railroad Commission routinely publishes in real time.
The commission’s Seismic Response Areas list general restrictions, including volume reductions and permit suspensions, but the public-facing pages do not name specific wells or permit numbers suspended on any given date. Without that granularity, outside researchers can see that regulators are acting in broad zones but cannot easily quantify which operators are bearing the brunt of the limits, or how quickly those actions follow new seismic clusters. That opacity makes it harder to evaluate whether the state is targeting the highest-risk wells or spreading cuts more evenly across an area.
Another limitation is spatial resolution. ComCat locations for small to moderate earthquakes can carry uncertainties of a few kilometers or more, especially in regions with sparse station coverage. Injection wells in the Permian Basin and other Texas plays are often tightly spaced, so an epicentral uncertainty ellipse can encompass dozens of potential culprits. TexNet’s denser array improves relative locations, but reconciling its catalogs with ComCat and with Railroad Commission permit data requires technical work that is not yet standardized in public reporting.
Temporal mismatches add complexity. Injection data are reported monthly, while earthquakes are logged to the second. A well might ramp up injection over the course of several weeks before a noticeable change in seismicity appears. Conversely, regulators may order a cutback that takes days to implement, during which earthquakes continue. Aggregating everything to monthly averages risks smoothing out the very spikes and drops that would reveal a causal link.
What the numbers can and cannot tell policymakers
Despite these gaps, the 64-versus-29 comparison still carries policy implications. California’s dozens of daily quakes are a reminder of an unavoidable geologic hazard that demands building codes, early warning systems, and public education. Texas’s smaller but rising counts point to a hazard that, at least in part, is industrially amplified and potentially reversible. That distinction should shape how each state invests in mitigation.
For Texas, the key question is not whether every earthquake can be traced to a specific well, but whether the overall pattern responds to regulatory pressure. If, over the next several years, seismic rates in Seismic Response Areas fall faster than in comparable regions where injection continues largely unchanged, it would support the argument that targeted volume reductions work. If the rates do not budge, or if activity simply migrates to new zones as operators seek more permissive permits, regulators may need to reconsider the scope and speed of their interventions.
Policymakers weighing stricter limits also have to balance economic and safety considerations. Oil and gas production remains a major employer and revenue source in Texas, and disposal wells are integral to that system. Yet induced earthquakes pose risks to homes, pipelines, and other infrastructure, and they can erode public trust in both industry and government. Transparent, data-driven decisions-grounded in catalogs like ComCat, injection reports, and independent monitoring-offer the best chance of threading that needle.
Ultimately, the contrasting daily tallies in California and Texas underscore that earthquake counts alone are not a measure of how well a state is managing seismic risk. What matters is the mix of natural and human-driven forces behind those numbers, and whether regulators are willing and able to act when the ground starts shaking for reasons within their control.
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*This article was researched with the help of AI, with human editors creating the final content.
