Omaha’s Pacific Street sinkhole became an internet event after a patch of the roadway collapsed in February, swallowing a silver Ram pickup truck and a maroon Jeep Cherokee. Video of the moment spread quickly from around the world, but officials and geologists said the widely seen failure was the kind of dramatic outlier that stands out only because most cave-ins are much smaller and draw little attention.
City and geology experts traced the larger collapses not to the deep, natural karst landscapes seen elsewhere, but to the interaction between Omaha’s soil and water moving through city infrastructure. In explaining the conditions that make the problem possible, they pointed to fine-grained sediment called loess—material that can be carried away by water—along with an urban environment shaped by pipes, sewers and storm systems that can leak over time.
Harmon Maher, a retired geology professor who walked near the Keystone Trail in central Omaha in February, said he noticed something odd before the public incident. He reported that the creek next to the path, normally a gray-green color, ran bright orange; he reasoned it was sediment likely washed in from construction upstream. Maher did not connect it immediately to the later collapse, until his son alerted him as a section of Pacific Street began failing.
Austin Rowser, Omaha’s city engineer, said the Pacific Street collapse began months earlier as a small leak in a Metropolitan Utilities District water main. Rowser said the leak found its way into the storm sewer, creating a small void that went undetected until the buildup of water-transported dirt eventually produced a cavity large enough to collapse under two vehicles on Feb. 24.
The explanation is part of a dispute that Rowser said has left the city and MUD in a “chicken-and-egg” argument over which infrastructure failure came first. MUD challenged the city’s account, contending that damage to the storm sewer caused the sinkhole and that the water main broke after the collapse. Both sides have filed claims against each other for repair costs.
Geologists said Omaha’s sinkholes also differ from the large collapses that can be associated with dissolvable bedrock. Joeckel, Nebraska’s state geologist, said the state has little karst topography compared with places such as the Missouri Ozarks and Florida’s “Sinkhole Alley,” where dissolvable bedrock can create more massive sinkhole conditions. He said Omaha’s collapses are typically shallower and often linked to how human-made infrastructure affects the loess blanket under eastern Nebraska.
Rowser said loess supports farming but poses challenges for roadbuilding and infrastructure because it can be carried away underground. “It’s great for growing corn, but terrible for building roads,” he said. In addition, he said Omaha’s hilly topography can aid the movement of water through the subsurface, helping move sediment and contributing to void formation.
Even with the rarity of dramatic viral collapses, officials described cave-ins as a recurring issue in the city. Over the last five years, city work crews reported more than 2,100 cave-ins—ranging from small dips in pavement to larger chasms like Pacific Street—according to analysis cited in the report. Rowser said many of Omaha’s cave-ins show up as minor surface defects, and that the city ordered barricades for about 40% of cave-ins that indicated a hazard at the surface.
Rowser also said the pattern changes with the seasons. He said Omaha sees far more sinkholes in warmer months because frozen soil doesn’t erode as easily. He contrasted that with potholes, which he said typically form during freeze-thaw cycles when moisture seeps into cracks in pavement in late winter and early spring.
UNO geology professor Ashlee Dere said Omaha’s frequency of cave-ins is not surprising given the city’s soil type, human-altered topography and aging infrastructure. “It’s surprising in that it doesn’t cause more problems,” Dere said. She and others referenced past Omaha sinkhole events, including a 2014 collapse on St. Mary’s Avenue that swallowed a car and injured its driver, and a downtown sinkhole last year that sucked half of a garbage truck into 16th Street and was still being repaired after a dispute involving a property owner.
For residents, officials said the odds of personal harm remain low, even if the risk of underground voids persists. Rowser said Omaha drivers should not worry about falling into a sinkhole because the chance is low, noting that the two drivers in the Pacific Street collapse emerged unharmed. Still, Joeckel said local engineers need to build and maintain on soil that can erode rapidly.
The city’s response focuses on identifying why a pavement collapse happened and stopping the underlying leak or void from expanding. Rowser said Public Works investigates every cave-in report to find the root cause. He said workers often start by injecting colored dye into a hole or crack in the pavement; if workers see the dye in sewer water downstream, it indicates water and sediment are likely leaking into the sewer. From there, teams can send cameras downstream to trace where the water enters so that repairs can stop the leak.
If dye does not appear in the sewer, Rowser said the cause may instead involve an animal burrow or dead tree roots, and workers use a special concrete to fill the gap. In recent years, reported cave-ins have decreased from more than 500 in 2021 to about 340 last year, the report said, while geologists warned that aging underground systems could raise the city’s risk if leaks accumulate.
Rowser said the city has also been exploring additional diagnostic approaches in recent weeks, including using fiber optic cables to detect leaks in water lines and alert the city sooner. Joeckel said certain geological surveys could help identify where water is concentrated and where future trouble spots may develop. He said it would be “great if you could see what was going on below the surface before something happened,” emphasizing the limits of detecting underground issues before they break through.
After Pacific Street reopened about nine days later, Maher said the incident’s fame came from how people react to the unexpected: it showed solid ground giving way. He said he suspected the attention reflected “psychology” around being intrigued by surprises, adding that it was unexpected that the ground could suddenly collapse. Rowser, citing an UNO security camera that recorded the incident, said the viral clip captured something that still matters even if the online spread cannot change what the city must do next—investigate, repair, and keep watch for the next small warning sign.