There have been well over 1000 aftershocks with magnitudes M ≥ 0.5.

Last night there was the largest aftershock (so far) a magnitude M 5.4 earthquake.

It is clear that this sequence has involved at least 2 main faults. I interpret the mainshock (the M 6.4) to be on a northeast trending (striking) left-lateral strike-slip fault. This is largely because (1) the longer of the 2 aftershock trends is has this orientation and (2) the majority of field observations of surface rupture are along this orientation. The M 5.4 aftershock is located along the right-lateral northwest trending fault. The M 6.4 could be on the nw striking fault.

Lots of information about the regional tectonics is in my original report, so I won’t rehash that here.

https://earthquake.usgs.gov/earthquakes/eventpage/ci38457511/executive

USGS

Berkeley Seismology Lab

Social Media

Analog seismograph record from an instrument near the Grapevine. Mainshock and large aftershock are in view. Photo taken at CGS HQ in Sacramento. #RidgecrestEarthquake #SearlesValleyEarthquake pic.twitter.com/HmL5g0I8Yy — Nick Graehl (@nickgraehl) July 5, 2019

The fault also ruptured across Randsburg Wash Road (south of Hwy 178) and offset it approx 1.5 feet. The offset is more here because it’s focused on 2-3 fault strands instead of 5-6 strand at Hwy 178. #ridgecrest #earthquake pic.twitter.com/GSVbTd60Kw — Brian Olson (@mrbrianolson) July 5, 2019

I ran the coseismics through G-FAST and got the following slip model for the Searles Valley EQ. G-FAST adds some extra fault real-estate (i.e. to NE) to allow for bilateral rupture, but does a good job putting slip only where it should be. pic.twitter.com/EleHejDZez — Brendan Crowell (@bwcphd) July 5, 2019

Earthquake aftershocks could last months or even years, scientists say https://t.co/YMoq0pLMVX @r_valejandra — Ron Lin (@ronlin) July 5, 2019

Aftershocks are continuing and damage/injury reports are becoming more detailed after today's magnitude 6.4 between the Sierras and the Mojave Desert, near Ridgecrest, CA. See our recent web article for basic earthquake information and safety tips: https://t.co/y41yRoHZYP. pic.twitter.com/oCniHnRXry — SCEC (@SCEC) July 4, 2019

Ridgecrest earthquake video: Parents, kids scream as 6.4-magnitude quake rattles stage during July 4th performance https://t.co/OIcBHswdnf via @abc7 — CaliforniaDisasters (@CalDisasters) July 6, 2019

New surface rupture from latest earthquake. 35.64900, -117.48240 pic.twitter.com/xgBUOExshK — Rich Koehler (@faultcreeper) July 6, 2019

Preliminary finite fault model for today's California earthquake. ~50 km long, ~20 s duration, peak slip ~3m in this model. Deep slip at NW end of model probably not real. Updates will follow. pic.twitter.com/i5q4iFK0yF — Gavin Hayes (@gph_seismo) July 6, 2019

Earthquake batters Trona: Rockslides cut off town; water is scarce https://t.co/ugYcpujKiE — L.A. Times: L.A. Now (@LANow) July 6, 2019

#Video taken at Morongo Casino in Cabazon, California, at the moment 6.9 mag earthquake strikes in southern California minutes ago. pic.twitter.com/BLQxO0ZqBq — 1st Breaking News® 🇲🇽 (@1stBreakingNews) July 6, 2019

7.1 magnitude earthquake 150 miles away in Ridgecrest, Ca. This is in my 6th (very top) floor apartment in Glendale, Ca. Turn your volume on for the full effect! #earthquakes #earthquake #EarthquakeLA #earthquakecalifornia @earthquakeBot @USGSBigQuakes pic.twitter.com/ZCokTSHvgM — russell john (@russelljohnnn) July 6, 2019

7.1 magnitude earthquake 150 miles away in Ridgecrest, Ca. This is in my 6th (very top) floor apartment in Glendale, Ca. Turn your volume on for the full effect! #earthquakes #earthquake #EarthquakeLA #earthquakecalifornia @earthquakeBot @USGSBigQuakes pic.twitter.com/ZCokTSHvgM — russell john (@russelljohnnn) July 6, 2019

Aftershock activity comparison:

M7.1 succeeding aftershocks are 1.4x larger in numbers and, so far, released 6.5x more energy than aftershocks succeeding the M6.4 event two days ago (within ~4h) Largest expected aftershock M6.0-6.3 is still to come (or maybe not) pic.twitter.com/q2Bid6C6w0 — CATnews | Andreas M. Schäfer (@CATnewsDE) July 6, 2019

Too amped to sleep. https://t.co/B0y7x6xhwY — Tiegan Hobbs (@THobbsGeo) July 6, 2019

UPDATE: 2019.07.06

DOC's Acting State Geologist, Tim McCrink, on @kcranews showing the #RidgecrestQuake area seismic faults and explaining the aftershock sequence. https://t.co/44NWJUiDq2 @Cal_OES — DeptofConservation (@CalConservation) July 6, 2019

Second quake did not rupture 395 or any roads east of coso junction pic.twitter.com/HPz2DfRo0O — Ian Pierce (@neotectonic) July 6, 2019

Creating two pictures, one from the M6.4 to the M7.1 (top), and the second from the M7.1 onwards (bottom). This, to separate the two sequences (although that of the M6.4 continues to some extent after the M7.1). The green and blue lines materialize the M6.4 aftershock sequence. pic.twitter.com/atYSvNJvCp — Bertrand Delouis (@BertrandDelouis) July 6, 2019

Just ran the Ridgecrest slip model through G-FAST, M7.19, a bit over 3 m slip, still preliminary. pic.twitter.com/hmUD6uSRg4 — Brendan Crowell (@bwcphd) July 6, 2019

Today's large EQ in USA is a good example of how its not large earthquakes that kill people but poorly built/designed buildings and infrastructure. So far no reported fatalities. BBC News – California earthquake: Larger 7.1 magnitude quake hitshttps://t.co/PfVSqJPFQS — tectonictweets (@tectonictweets) July 6, 2019

Animation of the #SoCalEarthquake sequence made using the IRIS Interactive Earthquake Browser. This covers the time period 7/4-to 7/6 17:00 UTC and uses USGS #earthquake locations. https://t.co/o0PzvGOiJH pic.twitter.com/f12FJXhi13 — IRIS Earthquake Sci (@IRIS_EPO) July 6, 2019

View the #SoCalQuake sequence on the IRIS Interactive Earthquake Viewer. You can even view the #earthquake hypocenters in 3D (like in the black image below) and animate the aftershock sequence! https://t.co/Gs3ykBEp0y pic.twitter.com/RsK6kQ2T4v — IRIS Earthquake Sci (@IRIS_EPO) July 6, 2019

Earthquakes near Ridgecrest were clearly in an red zone in the Coulomb failure stress changes (ΔCFS) analysis by Verdecchia and Carena, Tectonics (2016) 10.1002/2015TC004091. Would be great to see an after-event update? and see the impact on Garlock Fault. pic.twitter.com/VWh6po02dg — Anne-Sophie Meriaux 🇪🇺 (@Tecto_Asm) July 6, 2019

This mornings findings in the Trona pinacles area along the #Ridgecrest surface rupture with @neotectonic Think we Found southern extent of rupture pic.twitter.com/YhkgQA2aUF — Rich Koehler (@faultcreeper) July 6, 2019

DOC California Geological Survey's Janis Hernandez measures an offset on Highway 178. She's 1 of 20 geologists deployed to survey the effects of #RidgecrestEarthquake #earthquakeresponse @USGS @Cal_OES #cgs pic.twitter.com/LY3vv0H9uR — DeptofConservation (@CalConservation) July 6, 2019

Chris was in the field this morning and saw an offset anthill with about ~ 1 ft RL displacement from M7.1. His pictures below: pic.twitter.com/WwqXq1giz6 — Danielle Madugo (@DanielleVerdugo) July 6, 2019

1m of right lateral displacement of tire tracks, a dirt road and a fence. Pretty amazing. And we are at the southern part of the rupture pic.twitter.com/Fl4cIKvyr1 — Colin Chupik (@ChupikColin) July 6, 2019

More from today. Tiny pull aparts, pressure ridges and wide zones of deformation… pic.twitter.com/TjJwCVOBOJ — Colin Chupik (@ChupikColin) July 6, 2019

Just got into cell range from the 7.1 rupture where it crosses the 178. Just south of there, it crosses a dirt road with 1 strand with ~2ish ft RL and some vertical and another strand with very minimal RL and diffuse vertical displacement. NBC is camped on the RL and main strand. pic.twitter.com/54qxfaEHrk — Danielle Madugo (@DanielleVerdugo) July 6, 2019

Latest view of aftershocks from the SoCal quakes + slip model of today's M7.1 rupture (projected on the surface+aligned along the fault). Looks like today's rupture went SE past the intersection of the two faults. SW-NE fault has been less active today in terms of aftershocks. pic.twitter.com/td2V75ukNS — Stephen Hicks 🇪🇺 (@seismo_steve) July 6, 2019

@Planetlabs satellite images shows complex and distributed rupture of the July 4th Mw 6.4 Ridgecrest #earthquake. You can make out subtle left-lateral motion in top left of image. pic.twitter.com/cFpI4wTz4m — Chris Milliner (@Geo_GIF) July 6, 2019

Nevada Geodetic Lab (next door to M6.4, M7.1 Searles Valley quakes) is analyzing their network and other data, more here https://t.co/mnJuhMXK53

Screenshot from NGL webpage pic.twitter.com/LFM5Mz3OLj — UNAVCO (@UNAVCO) July 6, 2019

Seismologists at Scripps created this plot of the #RidgecrestEarthquake sequences and magnitudes over time. There have been more than 2,400 aftershocks to date. pic.twitter.com/mOgXQzCyz4 — Scripps Oceanography (@Scripps_Ocean) July 6, 2019

Seismologists at Scripps created this plot of the #RidgecrestEarthquake sequences and magnitudes over time. There have been more than 2,400 aftershocks to date. pic.twitter.com/mOgXQzCyz4 — Scripps Oceanography (@Scripps_Ocean) July 6, 2019

UPDATE: 2019.07.07