1928 – Helena, MT – M 5½ ±

Intermountain Seismic Belt Historical Earthquake Project

February 29, 1928 – Helena, MT – M 5½ ±

The 1928 Helena, Montana earthquake had no reported injuries or damage. The shaking startled people throughout the city of Helena and was more noticeable on upper floors of buildings with two or more stories above ground. The shaking was severe enough to disrupt a trial in one city courthouse. Without taking time to formally adjourn the proceedings, the judge and others fled the courtroom as the shaking began.

The earthquake was reported felt in areas southeast of Helena including: Trident, Three Forks, Manhattan, Logan, Lombard, and Sixteen-Mile Canyon. White Sulphur Springs, to the east of Helena, also reported earthquake shaking.

There were reports of shaken buildings, windows rattling, furniture moving, and goods being shaken from shelves.

 

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1947 – Virginia City, MT – M 6¼

Intermountain Seismic Belt Historical Earthquake Project

November 23, 1947 – Virginia City, MT – M 6¼

The Virginia City earthquake was reported felt in several communities in Montana, including: Billings, Missoula, Lewistown, Livingston, Helena, Harlowton, Malta, Havre, Glasgow, Kalispell, and Bozeman; and as far south as Idaho Falls, Idaho.

In most areas, the earthquake rocked buildings with, what was described in Helena as, a “long and easy” motion. There were widespread reports of swaying light fixtures, stopped clocks, dishes rattling, and window blinds and curtains moving back and forth. Cracks in plaster were observed and a plaster ceiling fell in a café in Hamilton.

Near the epicenter, in Virginia City, bricks and plaster were shaken loose from buildings, windowpanes were shattered, walls were cracked, and chimneys damaged. There were also reports of pictures being shaken off walls and dishes falling from cupboards.

In some locations sleeping residents were awakened as the shaking dislodged icicles from rooftops. Strange noises were reportedly heard during the shaking, and some residents fled their homes in fear. However, there were no reports of injuries or significant damage resulting from the earthquake.

 

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1988 – San Rafael Swell, UT – M 5.3

Intermountain Seismic Belt Historical Earthquake Project

August 14, 1988 – San Rafael Swell, UT – M 5.3

This earthquake was located approximately 10 miles ESE of Castle Dale, Utah in Emery County.

There were no reports of injuries or serious damage resulting from the earthquake. Reports indicate that the earthquake was felt as far east as Golden, Colorado, as far south as Albuquerque, New Mexico, as far west as Delta, Utah, and as far north as Brigham City, Utah. The earthquake was reportedly felt particularly in valleys, while less noticed in mountain areas.

Minor damage in Emery County consisted of cracks in foundations, chimneys, and old buildings. Dishes and store goods fell from shelves and pictures were dislodged from wall hooks. Cracks and plaster damage were also observed in ceilings and walls.

Calls about the earthquake were received from several coal mines in the area, but there were no reports of injury or damage. Local dams were examined and found to be sound.

Rock falls were a notable feature of this earthquake. Fallen boulders impeded travel on some roadways. In many locations, falling rocks sent up clouds of dust that were visible for many miles.

Near the epicenter, north of Ferron, Utah a resident reported seeing dust clouds on the western ridge that partially obscured Ferron Mountain and the cliffs around the Wilberg Mine. “You couldn’t see the mountain up around Wilberg for five to 10 minutes because of the dust. Same on the desert [to the east]. Just a big string of dust from as far south to as far north as you could see.”

 

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1934 – Hansel Valley, UT – M 6.6

Intermountain Seismic Belt Historical Earthquake Project

March 12, 1934 – Hansel Valley, UT – M 6.6

Believed to be the most severe earthquake in Utah’s recorded history, the 1934 Hansel Valley earthquake was reportedly felt as far west as Elko, Nevada and as far east as Rawlins, Wyoming. Felt reports were also issued from as far north as Boise, Idaho and as far south as Richfield, Utah.

The main shock occurred approximately 30 miles north of the Great Salt Lake at 8:05 a.m. local time. Five significant aftershocks were recorded over a nearly eight-week period from March 12 to May 6, 1934.

Some of the most severe damage was reported in Logan, Utah and surrounding communities. At least two public buildings in the area had to be abandoned. A three-story brick building on the campus of the Utah State Agricultural College was, reportedly, split from top to bottom. In Preston, Idaho, the shaking dislodged a 150-pound capstone from the top of the local high school building, separating the west wall from the rest of the building.

Other reports of damage included falling chimneys, broken windows, cracked walls and falling plaster. Swinging light fixtures were observed during the earthquake. Furniture rocked back and forth or rolled across floors. Dishes and goods fell from shelves and clocks stopped. Near the epicenter, in Snowville, Utah, the water main was broken and out of service for 10 hours. In some locations schools were evacuated and closed, particularly following the first aftershock.

Near the epicenter of the earthquake the appearance of several fissures or cracks in the ground surface were observed. Witnesses reported hearing loud roars as the fissures ruptured. A geologist who later examined the area reported one of the fissures to be about eight miles in length. He found a maximum fissure width of 14 inches, with a maximum drop of the ground on one side measuring 19 inches. Other reports noted a downward displacement of the ground on the east of the larger, predominantly north-south trending fissures.

Phenomena described as sand or mud cones were observed near the epicenter. There were also sightings of new springs and streams changing course. Artesian wells that had been long dry began flowing with water. Other wells, active prior to the earthquake, ceased to flow for several hours.

In many locations, shaking from the earthquake sent people running out of doors. There were also reports of people fainting from fright. In areas of intense shaking, people were unable to stand during the earthquake.

Two deaths were attributed to the earthquake. Ida Atkinson died instantly from a heart attack upon hearing that the shaking she felt was due to an earthquake. Salt Lake City waterworks employee Charles Bithel was injured when a six-foot trench in which he was working at the time of the earthquake caved in. Bithel died from his injuries the following day in a local hospital.

 

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1959 – Kanab, UT – M 5.7

Intermountain Seismic Belt Historical Earthquake Project

July 21, 1959 – Kanab, UT – M 5.7

This earthquake was felt over an area of 21,000 square kilometers, primarily in southern Utah and northern Arizona, according to newspaper accounts. Dishes and canned goods were knocked to the floor, cars were jostled on roads, and minor rockslides occurred. Felt reports were received from as far south as Flagstaff, Arizona–approximately 195 miles from the epicenter.

Near the epicenter, in the Kanab-Fredonia area, there were also reports of windows and dishes breaking, as well as canned goods tumbling from market shelves. In Kanab, the police chief reported bricks falling from at least one chimney. And plaster in the county courthouse was shaken from the walls. A truck driver traveling through the area at the time of the earthquake related that he “thought his steering had gone haywire.”

The earthquake, which occurred at 10:39 am local time, sent frightened Kanab residents scurrying from their homes–but no injuries or significant damage was reported.

 

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1915 – Provo, UT – M 5.0

Intermountain Seismic Belt Historical Earthquake Project

July 15, 1915 – Provo, UT – M 5.0

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According to newspaper accounts this earthquake was felt throughout the Utah, Salt Lake, and Bear River Valleys, and also in Provo Canyon, Tooele, Parley’s Canyon, and Park City, Utah.  The felt area measured 13,000 square kilometers.

In parts of Utah Valley buildings swayed, chimneys toppled, building walls were cracked, and individuals were knocked from chairs and couches. Wallpaper was split over doors and plaster was cracked and shaken loose. Dishes and pans rattled. In Provo Canyon shaking from the earthquake caused rockslides which blocked at least one road. At Utah Lake an upheaval of water, like a small tidal wave, was sighted.

In the Salt Lake Valley clocks stopped, windows and dishes rattled, and furniture was knocked over. Cans and packages were shaken from grocery store shelves.

Shaking appeared to be more pronounced in the upper floors of taller buildings both in Provo and Salt Lake City. In some locations both in the Utah and Salt Lake Valleys, the shaking caused individuals to rush out of buildings. This was the case throughout Provo where people hurried into the streets wondering what had happened. It was reported that more than an hour passed before the city resumed normal activities.

There were no reports of injuries or significant damage from the earthquake.

 

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1975 – Yellowstone National Park, WY – M 6.1

Intermountain Seismic Belt Historical Earthquake Project

June 30, 1975 – Yellowstone National Park, WY – M 6.1

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This earthquake was located approximately 5 miles ESE of Norris Junction, in Yellowstone National Park. According to newspaper accounts, no casualties resulted from the earthquake and damage was minor. Near the epicenter, telephone service was temporarily knocked out. The earthquake also dislodged boulders that temporarily blocked a road between Norris and Madison Junction – however, campgrounds and park facilities remained open.

A park service employee reported, “There wasn’t any noise; no dishes rattled. There was just a gentle rolling of the floor.”

The earthquake shook buildings and rattled windows 200 miles away from the epicenter, and was reported felt both in Great Falls and Billings, Montana. The total felt area of the earthquake was 50,000 square kilometers.

A significant aftershock (magnitude 5.5) occurred just over 17 months later on December 8, 1976, approximately 5 miles W of Norris Junction. This earthquake was the largest since the June 30, 1975 main shock, and was felt over an area of 5,000 square kilometers.

Park officials noted that the aftershock shook buildings, but no damage was reported. One park official believed that damage to the terrain would likely be limited to rockslides. The earthquake occurred after the close of the summer tourist season – the park service received no inquiries about the earthquake from individuals inside park boundaries.

 

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