RENO — Reno faces a “small increase” in the chance of a major earthquake after a swarm of temblors caused high-rise casinos to sway and put visitors and residents on edge, scientists said Friday.
More than 125 mostly minor temblors rattled the Reno area over a 24-hour period ending Friday afternoon, the strongest a magnitude 4.2 quake that struck shortly before 4 p.m. Thursday.
No major damage or injuries were reported.
Hundreds of other quakes, all magnitude 3.5 or lower, have occurred since Feb. 28 in the same sequence centered around the community of Mogul, just west of Reno.
“The persistence of this particular earthquake sequence slightly increases the probability for a significant earthquake in west Reno,” said a statement issued by the Nevada Seismological Laboratory at the University of Nevada, Reno.
“However, the occurrence of additional earthquake activity in the Mogul area cannot be predicted or forecast,” it added.
Chances of a temblor with a magnitude of 6 or greater striking somewhere around Reno within the next 50 years is 34 percent to 98 percent, according to a study released in 2006 by the Nevada Bureau of Mines and Geology.
Ken Smith, a seismologist at the university lab, said the recent activity around Reno is unusual in that the quakes started out small and continue to build in strength. The normal pattern is for a main quake followed by smaller aftershocks, such as the Feb. 21 quake in the northern Nevada town of Wells.
The magnitude 6 temblor in Wells, 350 miles east of Reno, has been followed by hundreds of smaller aftershocks. The quake caused an estimated $778,000 in damage to homes, schools and historic downtown buildings there.
“If the pattern continues we may be looking at a larger event” in the Reno area, Smith said Friday. “We wouldn’t be surprised to see it (swarm) end at any time and it also wouldn’t be surprising to see a large earthquake. The bottom line is we don’t know what will happen.”
More than 70 aftershocks were reported Friday, including separate magnitude 3.3 quakes that struck shortly after 1:30 a.m. and 10:30 a.m.