2019 Ridgecrest earthquakes

2019 Ridgecrest earthquakes
2019 Ridgecrest earthquakes is located in California
Ridgecrest
Ridgecrest
Los Angeles
Los Angeles
Bakersfield
Bakersfield
Las Vegas
Las Vegas
Sacramento
Sacramento
San Diego
San Diego
Tijuana
Tijuana
2019 Ridgecrest earthquakes
UTC time 
 A: 2019-07-04 17:33:49
 B: 2019-07-05 11:07:53
 C: 2019-07-06 03:19:52
 D: 2020-06-04 01:32:11
ISC event 
 A: 616217956
 B: 616043696
 C: 616203758
USGS-ANSS 
 A: ComCat
 B: ComCat
 C: ComCat
 D: ComCat
Local date 
 A: July 4, 2019 (2019-07-04)
 B: July 5, 2019 (2019-07-05)
 C: July 5, 2019 (2019-07-05)
 D: June 3, 2020 (2020-06-03)
Local time 
 A: 10:33 a.m. PDT
 B: 4:08 a.m. PDT
 C: 8:19 p.m. PDT
 D: 6:32 p.m. PDT
Magnitude 
 A: Mw6.4[1]
 B: Mw5.4[2]
 C: Mw7.1[3]
 D: Mw5.5[4]
Depth 
 A: 10.7 km (6.6 mi)
 B: 7.0 km (4.3 mi)
 C: 8.0 km (5.0 mi)
 D: 6.8 km (4.2 mi)
Epicenter35°45′58″N 117°36′18″W / 35.766°N 117.605°W / 35.766; -117.605
TypeStrike-slip
Areas affectedCalifornia, Nevada, Arizona
Total damage$5.3 billion[5][6]
Max. intensityMMI IX (Violent)
Peak acceleration0.48 g[7]
Foreshocks2 (≥2.5 Mw )
(including before main foreshock)
Aftershocks4,000
~1,200 (≥2.5 Mw )
(including after main foreshock)
Casualties1 death, 25 injured (20 on July 4, 5 on July 5)

The 2019 Ridgecrest earthquakes (more commonly referred to in scientific literature as the 2019 Ridgecrest earthquake sequence) of July 4 and 5 occurred north and northeast of the town of Ridgecrest, California located in Kern County and west of Searles Valley (approximately 200 km [122 mi] north-northeast of Los Angeles). They included three initial main shocks of Mw magnitudes 6.4, 5.4, and 7.1,[8] and many perceptible aftershocks, mainly within the area of the Naval Air Weapons Station China Lake. Eleven months later, a Mw  5.5 aftershock took place (the largest aftershock of the sequence) to the east of Ridgecrest. The first main shock (now deemed to be a foreshock) occurred on Thursday, July 4 at 10:33 a.m. PDT, approximately 18 km (11.2 mi) ENE of Ridgecrest, and 13 km (8.1 mi) WSW of Trona,[9] on a previously unnoticed NE-SW trending fault where it intersects the NW-SE trending Little Lake Fault Zone.[10] This quake was preceded by several smaller earthquakes, and was followed by more than 1,400 detected aftershocks. The M 5.4 and M 7.1 quakes struck on Friday, July 5 at 4:08 a.m. and 8:19 p.m. PDT approximately 10 km (6 miles) to the northwest. The latter, now considered the mainshock, was the most powerful earthquake to occur in the state in 20 years (after the 1999 Hector Mine earthquake).[11] Subsequent aftershocks extended approximately 50 km (~30 miles) along the Little Lake Fault Zone.

Relatively minor damage resulted from the initial foreshock, though some building fires were reported in Ridgecrest near the epicenter. The main quake on July 5 cut power to at least 3,000 residents in Ridgecrest.[12][11] Effects were felt across much of Southern California, parts of Arizona and Nevada,[13] as far north as the San Francisco Bay Area and Sacramento, and as far south as Baja California, Mexico. An estimated 20 million people experienced the foreshock, and approximately 30 million people experienced the mainshock.[14]

  1. ^ ANSS: Ridgecrest 2019a .
  2. ^ ANSS: Ridgecrest 2019b .
  3. ^ ANSS: Ridgecrest 2019c .
  4. ^ ANSS: Ridgecrest 2019d .
  5. ^ Cite error: The named reference KTLA_0710 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference KTLA_0814 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference StEER was invoked but never defined (see the help page).
  8. ^ ANSS: Ridgecrest 2019a . ANSS: Ridgecrest 2019b . ANSS: Ridgecrest 2019c .
  9. ^ ANSS: Ridgecrest 2019a, "Regional Information" .
  10. ^ ANSS: Ridgecrest 2019c . "Tectonic Summary".
  11. ^ a b "7.1-Magnitude Earthquake Hits Southern California; Experts Say More Strong Aftershocks Possible". The Weather Company. July 6, 2019. Retrieved July 6, 2019.
  12. ^ Cite error: The named reference Stronger quake LATimes was invoked but never defined (see the help page).
  13. ^ "Northern Ireland pair shaken by quake on 30th floor of Las Vegas hotel". Belfast Telegraph. ISSN 0307-1235. Retrieved May 15, 2020.
  14. ^ Byrd, Doborah (July 6, 2019). "California shakes from 2nd big quake in 2 days". EarthSky. Retrieved July 7, 2019.