{"id":5623,"date":"2026-07-13T10:06:45","date_gmt":"2026-07-13T17:06:45","guid":{"rendered":"https:\/\/tungsten2.gps.caltech.edu\/?p=5623"},"modified":"2026-08-06T13:31:01","modified_gmt":"2026-08-06T20:31:01","slug":"07-13-2026-m4-3-near-johannesburg","status":"publish","type":"post","link":"https:\/\/www.scsn.org\/index.php\/2026\/07\/13\/07-13-2026-m4-3-near-johannesburg\/","title":{"rendered":"07\/13\/2026, M4.3 near Johannesburg"},"content":{"rendered":"<p><b>Event<\/b><\/p>\n<ul>\n<li>13 Jul 2026 09:40:55 PDT, (35.312, -117.817), depth 7.0km.<\/li>\n<li>18km WSW  of Johannesburg, California<\/li>\n<\/ul>\n<p><b>Aftershocks<\/b><\/p>\n<ul>\n<li>As of 13 Jul 2026, 10:02AM PDT, there have been 5 aftershocks recorded.<\/li>\n<li>The largest was M2.3 (smallest M1.0).<\/li>\n<li>More aftershocks may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock.<\/li>\n<li>There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.<\/li>\n<\/ul>\n<p><b>Possible Foreshocks<\/b><\/p>\n<ul>\n<li>There were 12 events during the 3 days prior to the earthquake (within a 10 km radius).<\/li>\n<li>The largest was M2.1 (2026\/07\/11).<\/li>\n<\/ul>\n<p><b>Historical Seismicity<\/b><\/p>\n<ul>\n<li>Since our records began in 1932 we&#8217;ve had 5 events of M4 or greater within 10km of today&#8217;s event.<\/li>\n<li>The largest historic event was M4.6 on 1944\/07\/03.<\/li>\n<li>The most recent historic event was M4.1 on 01 Jun 2026.<\/li>\n<\/ul>\n<p><b>ShakeAlert Response<\/b><\/p>\n<ul>\n<li>The ShakeAlert system was activated. It had a maximum magnitude estimate of M4.6, so alerts could have been issued to the public via cell phone apps. This event did not meet the threshold for alerts via the Wireless Emergency Alert system.<\/li>\n<\/ul>\n<p><b>Relocated Sequence Model<\/b><br \/>\n<div class=\"scsn-html-iframe-embed\"><iframe src=\"https:\/\/www.scsn.org\/wp-content\/uploads\/html-iframe-embeds\/596f8453-fbd9-47b4-a36d-2611ed0dff9b\/index.html\" title=\"2026 Johannesburg v2\" loading=\"lazy\" sandbox=\"allow-scripts allow-forms allow-popups allow-downloads\" referrerpolicy=\"strict-origin-when-cross-origin\" style=\"display:block;width:100%;height:700px;border:0;\" width=\"100%\" height=\"700\"><\/iframe><p style=\"margin:8px 0 0;text-align:right;\"><a href=\"https:\/\/www.scsn.org\/wp-content\/uploads\/html-iframe-embeds\/596f8453-fbd9-47b4-a36d-2611ed0dff9b\/index.html\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open 2026 Johannesburg v2 in a new tab\" style=\"display:inline-block;padding:7px 12px;border:1px solid #767676;border-radius:3px;background:#f6f7f7;color:#1d2327;text-decoration:none;font-size:14px;line-height:1.4;\">Open in a new tab<\/a><\/p><\/div><br \/>\n<span style=\"display:block; height:0.25em;\"><\/span><br \/>\n<img decoding=\"async\" src=\"https:\/\/tungsten2.gps.caltech.edu\/wp-content\/uploads\/johannesburg_map-scaled.png\" alt=\"2026 Johannesburg Map\"style=\"width:100%; height:auto; align:center; display:block;\"\/><\/p>\n<p>This map, and 3d model above, shows the locations of earthquakes in the 2025-26 Johannesburg swarm, in Kern County in Southern California\u2019s High Desert. They were generated using a refined technique called HypoDD (Hypocenter Double-Difference) relocation, which determines earthquake locations by comparing pairs of nearby earthquakes recorded at the same station, rather than relying solely on the absolute travel time of waves through the Earth\u2019s crust. The result is a much more accurate picture of where the earthquakes are actually occurring. Each circle represents one earthquake, with the size scaled to its magnitude and the color indicating when it happened, letting you see how the seismicity evolved over time. The largest red circle (red diamond in 3d model) marks the largest event in this sequence so far, the M4.3 on 2026\/07\/13. The two smaller panels along the bottom and right side show depth cross-sections, which help reveal the geometry of the fault system at depth. The map includes events from the beginning of 2025 and is current as of 2026\/07\/17, 19:53:31UTC. 3d model as of 2026\/08\/06.\n<\/p>\n<p><b>Faults<\/b><\/p>\n<ul>\n<li>CFM fault associations: most likely . Alternates: Garlock fault-east (18%), Other CFM faults (4%).<span>&#42;<\/span><\/li>\n<li>Nearby faults: Garlock fault zone, central Garlock section (2.1 km), Garlock fault zone, central Garlock section (Garlock fault) (5.5 km), Garlock fault zone, western Garlock section (5.9 km), Garlock fault zone, central Garlock section (El Paso fault) (8.5 km) and Lenwood-Lockhart fault zone, Lenwood section (Lockhart fault) (10.0 km).<span>&#42;&#42;<\/span><\/li>\n<\/ul>\n<p><b>Additional Information<\/b><\/p>\n<ul>\n<li>Links for: <a href=\"https:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/ci41292687#executive\">USGS earthquake page<\/a>, <a href=\"https:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/ci41292687\/shakemap\/intensity\">ShakeMap<\/a>, <a href=\"https:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/ci41292687\/dyfi\/intensity\">DYFI<\/a>, <a href=\"http:\/\/pasadena.wr.usgs.gov\/eqview\/cgi-bin\/makePublicView.php?EVID=41292687\">waveforms<\/a>.<\/li>\n<li>Visit our <a href=\"\/index.php\/earthquakes\/speqrep\/\">special reports page<\/a> for further information on local notable earthquakes.<\/li>\n<li>Visit <a href=\"https:\/\/scedc.caltech.edu\/\">scedc.caltech.edu<\/a> to access any data recorded by the SCSN.<\/li>\n<\/ul>\n<p><\/br><\/p>\n<p>Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.<\/p>\n<p><iframe loading=\"lazy\" title=\"07\/13\/2026, M4.1 near Johannesburg, Local Event\" width=\"605\" height=\"340\" src=\"https:\/\/www.youtube.com\/embed\/MITBSMkU7x0?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><br \/>\n<b>Energy Propgation<\/b><br \/>\n<iframe loading=\"lazy\" title=\"M4.3 Johannesburg 2026\/07\/13 Energy Propogation\" width=\"605\" height=\"340\" src=\"https:\/\/www.youtube.com\/embed\/voVSDcpP4gw?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>Seismic energy propagating across the Southern California Seismic Network following this earthquake. Each circle represents an SCSN station, with warmer colors indicating stronger energy at a four-second period. The close-up highlights how seismic waves can become trapped within the Los Angeles Basin, causing the warmer colors to linger.<\/p>\n<p><b>Ridgecrest DAS array<\/b><br \/>\n<iframe loading=\"lazy\" title=\"M4.3 Johannesburg 2026\/07\/13 DAS\" width=\"605\" height=\"340\" src=\"https:\/\/www.youtube.com\/embed\/edEHusijgBk?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>A magnitude 4.3 earthquake near Johannesburg, CA, recorded by the Ridgecrest DAS Array. Darker colors indicate greater strain along the fiber-optic cable and stronger seismic energy. Distinct P and S waves, along with later reflections and smaller aftershocks, can be seen traveling across the array.<\/p>\n<p><small><\/p>\n<p><span>&#42;<\/span>Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the <a href=\"https:\/\/www.scec.org\/research\/cfm\" target=\"_blank\">Community Fault Model (CFM)<\/a> provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.<\/p>\n<p>CFM Fault: SCEC CFM 7.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth &#038; Planetary Sciences.<\/p>\n<p>Probability: The probability in percent the earthquake is associated with this fault.<\/p>\n<p>SCSN: Caltech\/USGS Southern California Seismic Network<\/p>\n<p><span>&#42;&#42;<\/span>U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: <a href=\"https:\/\/earthquake.usgs.gov\/hazards\/qfaults\/\">https:\/\/earthquake.usgs.gov\/hazards\/qfaults\/<\/a><\/p>\n<p><\/p>\n<p>This information is subject to change as more up-to-date data become available.<\/p>\n<p><\/small><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Event 13 Jul 2026 09:40:55 PDT, (35.312, -117.817), depth 7.0km. 18km WSW of Johannesburg, California Aftershocks As of 13 Jul 2026, 10:02AM PDT, there have been 5 aftershocks recorded. The largest was M2.3 (smallest M1.0). More aftershocks may be expected<span class=\"ellipsis\">&hellip;<\/span><\/p>\n<div class=\"read-more\"><a href=\"https:\/\/www.scsn.org\/index.php\/2026\/07\/13\/07-13-2026-m4-3-near-johannesburg\/\">Read more &#8250;<\/a><\/div>\n<p><!-- end of .read-more --><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,15],"tags":[825,824,70,94],"class_list":["post-5623","post","type-post","status-publish","format-standard","hentry","category-zack","category-local_earthquake","tag-07-13-2026","tag-824","tag-johannesburg","tag-m4-1"],"_links":{"self":[{"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/posts\/5623","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/comments?post=5623"}],"version-history":[{"count":13,"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/posts\/5623\/revisions"}],"predecessor-version":[{"id":5672,"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/posts\/5623\/revisions\/5672"}],"wp:attachment":[{"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/media?parent=5623"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/categories?post=5623"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.scsn.org\/index.php\/wp-json\/wp\/v2\/tags?post=5623"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}