1921 Sevier Valley earthquake
38°41′N 112°09′W / 38.68°N 112.15°W / 38.68; -112.15
The 1921 Sevier Valley earthquake was a series of three earthquakes. The primary quake was a magnitude Mw6.3 earthquake that occurred on Thursday, 29 September 1921 at approximately 7:12 AM MT in Elsinore, Utah, United States. The first aftershock occurred in the evening on the same day, and a second aftershock occurred two days later on 1 October. No people were killed in the quake or in the subsequent aftershocks.
Earthquake
The primary earthquake struck on Thursday 29 September 1921 at approximately 7:12 AM MT in Elsinore, Utah, United States, lasting for 7–10 seconds.[1][2][3] This quake was preceded by several weeks of smaller quakes.[3] A major aftershock occurred on the same day at approximately 7:30 PM MT, and a second major aftershock occurred on Saturday, 1 October at approximately 8:32 AM MT.[3]
Magnitude and intensity
The initial quake was a Mw6.3 and an intensity of VIII ("Severe").[1][3][4] The official USGS report in their historical earthquakes list stated a magnitude of Mw5.2 and an intensity of VIII ("Severe").[2][5][6] An official USGS report published in 1988 assigned the modified magnitude of Mw6.3.[3] It was felt in an area of between 2,500 square kilometers (970 sq mi) and 5,100 square kilometers (2,000 sq mi), which is considered a small area for a quake of this size.[2][3] The farthest distance from the epicenter for the felt area was 25 miles (40 km). The quake lasted several seconds.[7]
The first major aftershock was a Mw5.7 and an intensity of VII ("Very Strong").[3] The epicenter was at the same location as the initial quake, and the felt area was similar.[3] The second major aftershock was the same magnitude and intensity as the initial quake, was in the same location, and felt in a similarly sized area.[3] This quake was reported as "quick and short as the detonation of a cannon".[3] The quakes were felt as far north as Salina and as far south as Marysvale.[1]
Destruction
Damage to chimneys and brick walls from the initial quake was "considerable".[3] Over US$100,000 in damage were caused (over US$1.44 million in 2020) by the primary quake.[8][9]
The town of Elsinore, reported sunken foundations, damaged roofs from collapsing chimneys and brick walls, and brick, adobe, and stone buildings were significantly damaged.[4] More than half of the residences in the town were seriously damaged, a dozen were damaged enough to be condemned, and most residences received some cracking and plaster damage.[3] The newly built schoolhouse had walls collapse and a damaged roof, causing it to have to be rebuilt.[7][8] Damage in Monroe included collapsed pipe trenches, cracked buildings, and the hot springs at the town turned "blood red" from iron oxide.[1][3] Large boulders were dislodged and some landslides were reported in canyons near Monroe.[1]
The first major aftershock—in the evening on the same day—did further damage to structures, especially those already affected by the primary quake.[1][3] Structures in Monroe received significantly more damage from this aftershock.[3] Damage was also reported in Richfield.[1]
On 1 October, the second major aftershock destroyed many of the damaged buildings, including a paint store in Elsinore. It also caused new damage to undamaged buildings, and caused previously-damaged buildings to be completely destroyed.[1][3] More large boulders were dislodged and additional landslides were caused in various canyons near the affected towns.[1] Monroe was especially hard hit, with almost all chimneys being destroyed and many buildings being damaged beyond repair.[1] A man seated high on a bank of a river was thrown down to the edge of the river, the hot springs were discolored by iron oxide again, and the Monroe City Hall was "shattered".[3]
No people were killed in the quake, though at least two were injured by falling bricks or plaster.[3]
References
- ^ a b c d e f g h i j Peterson, Sheryl (10 January 2020). "1921 – Elsinore, UT (series) – M 6 ±". University of Utah. Archived from the original on 20 April 2020. Retrieved 4 May 2020.
- ^ a b c "M 5.2 - Utah - Utah Overview". United States Geological Survey. Retrieved 4 May 2020.
- ^ a b c d e f g h i j k l m n o p q r Hopper, Margaret G. (4 April 1988). "Large Earthquakes in Sevier County, Utah, in 1901 and 1921" (PDF). United States Geological Survey. Open-File Report 88-404. Archived (PDF) from the original on 12 February 2017. Retrieved 4 May 2020.
- ^ a b Dunn, Scott (9 October 2012). "5 biggest earthquakes ever to happen in Utah". KSL.com. Archived from the original on 18 March 2020. Retrieved 1 May 2020.
- ^ "M 5.2 - Utah Impact Summary". United States Geological Survey. Retrieved 4 May 2020.
- ^ "M 5.2 - Utah - Utah Technical Summary". United States Geological Survey. Retrieved 4 May 2020.
- ^ a b "Utah is shaken by earthquake" (PDF). The Lehi Sun. 6 October 1921. p. 7. Retrieved 4 May 2020.
- ^ a b "Summary of Newspaper Articles" (PDF). University of Utah. Archived (PDF) from the original on 21 April 2020. Retrieved 4 May 2020.
- ^ "$100,000 in 1921 → $1,441,983.24 today". Official Data Foundation. Archived from the original on 4 May 2020. Retrieved 4 May 2020.
- v
- t
- e
- Veracruz (6.4, Jan 3) †
- Gori (6.2, Feb 20) †
- Garfagnana (6.5, Sep 7) †
- Haiyuan (7.8, Dec 16) †‡
- Mendoza (6.0, Dec 17)
- Massawa (6.1, August 14)† ‡
- Sevier Valley (6.3/5.7/6.3, Sep 29/Oct 1)
- 1st Kamchatka (8.4, February 3)
- Renda (7.0, March 24)†
- 2nd Kamchatka (8.2, Apr 13)†
- Torbat-e Heydarieh (6.0, May 25)†
- Great Kantō (8.1, September 1)† ‡
- Charlevoix–Kamouraska (6.2, Feb 28)
- Dali (7.0, Mar 16) †‡
- Montana (6.9, June 27)
- Santa Barbara (6.8, June 29)
- Chirpan–Plovdiv (7.1/7.1, Apr 14/Apr 18) †
- Chachapoyas (7.2, May 14)
- Talca (7.6, Dec 1) †‡
- Cumaná (6.9, Jan 17) †
- Arthur's Pass (7.1, Mar 9)
- Kopet Dag (7.2, May 1) †‡
- Suşehri (6.3, May 18) †
- Murchison (7.8, June 17)
- Grand Banks (7.2, Nov 18)
‡ indicates the deadliest earthquake of the year