WEBVTT Kind: captions Language: en 00:00:02.400 --> 00:00:06.880 strong that's enough to knock things  over really give you a rattle you'd   00:00:06.880 --> 00:00:10.400 hear lots of sounds and get  pretty uh may get alarmed by that.    00:00:11.600 --> 00:00:17.840 Shaking was felt quite widely from san  Francisco to east of Carson City in Nevada   00:00:17.840 --> 00:00:24.160 and as far south as Visalia California. Um shaking  related effects that we've heard of so far   00:00:24.160 --> 00:00:29.840 include rockfall along highway 395 near Coalville  that's right near the epicenter of the earthquake. 00:00:32.400 --> 00:00:38.400 The earthquake is the result of normal faulting  uh it's a pretty well understood and expected   00:00:38.400 --> 00:00:42.320 mechanism for an earthquake at the eastern  boundary of the Sierra Nevada mountains 00:00:43.200 --> 00:00:50.320 in the region that it in in which it happened. The  uh our Earthquake Early Warning system ShakeAlert 00:00:50.320 --> 00:00:56.960 detected the earthquake 25.6 seconds after  its origin uh the system underestimated the   00:00:56.960 --> 00:01:02.080 original magnitude of that event and an  estimated a location that was slightly   00:01:02.080 --> 00:01:07.520 off from the true location. That meant that  as the waves propagated across the state   00:01:08.480 --> 00:01:13.600 other stations misregistered the event so  several different shake alerts were sent out   00:01:13.600 --> 00:01:17.600 for earthquakes in different areas and  people who joined and visited our site upon   00:01:17.600 --> 00:01:24.000 feeling it really early will have seen multiple  different events show up sort of simultaneously.   00:01:24.000 --> 00:01:28.160 This is a fairly common thing that happens  at the beginning as our instruments are just   00:01:28.160 --> 00:01:32.800 detecting and automatically sending signals  from these earthquakes and so it's something   00:01:32.800 --> 00:01:37.920 that's somewhat to be expected. Uh it's worth  noting that this earthquake just like the large   00:01:37.920 --> 00:01:43.760 one that happened near Lake Tahoe a few weeks  ago happened at the border of the ShakeAlert 00:01:44.880 --> 00:01:52.560 region and so as we build out the system  further and develop install more instruments   00:01:52.560 --> 00:01:58.240 in the remote locations at the margins of  our of our state and the state that covers it   00:01:58.960 --> 00:02:03.200 that's covered by ShakeAlert these sorts  of errors will become less and less common.   00:02:04.240 --> 00:02:09.760 Um we have produced an aftershock forecast  for this event it shows that there's a six   00:02:09.760 --> 00:02:16.400 percent chance of one or more aftershocks larger  than the initial earthquake. I'll emphasize that   00:02:16.400 --> 00:02:25.600 a six percent chance is far less likely it's  it's uh the particularly unlikely scenario. Um   00:02:26.320 --> 00:02:32.640 more likely and as we've seen so far there have  been about 40 or 40 or more aftershocks so far   00:02:32.640 --> 00:02:37.040 smaller ones than the main event. Uh  the largest one so far was a magnitude   00:02:37.040 --> 00:02:46.720 4.5 and i believe there was just another 4.4  maybe 10 minutes ago. All this information you   00:02:46.720 --> 00:02:52.000 can sort of keep track along with the incoming  information on our website as many of us are doing. 00:02:56.560 --> 00:03:03.600 So this earthquake is not particularly uncommon  for the region it's a region with known active   00:03:03.600 --> 00:03:13.600 faults this happened uh along the trace of a  mapped fault and um it is the largest in the   00:03:13.600 --> 00:03:21.440 region since the magnitude 6.1 Double Spring Flat  earthquake which was about 36 kilometers to the   00:03:21.440 --> 00:03:29.120 northwest in 1994, but there have been other  earthquakes over the decades in this region.   00:03:29.120 --> 00:03:34.560 There have been about a couple dozen earthquakes  larger than magnitude 5 in the last 50 years here.   00:03:35.920 --> 00:03:42.160 The instrumentally recorded ground motions  across uh in our recorded by our sensors across   00:03:42.160 --> 00:03:49.040 the state are typical for this size of earthquake,  so reports of shaking that we've had at large   00:03:49.040 --> 00:03:56.320 distances in San Francisco, in Las Vegas, are what  we would expect for this event and there was   00:03:56.320 --> 00:04:03.120 likely some amplification in places that  are built on basin sediments and flat soils. 00:04:05.280 --> 00:04:08.720 That's the overview of the  earthquake that we've all um   00:04:08.720 --> 00:04:12.400 that we just experienced here  and the aftershocks that continue,   00:04:14.160 --> 00:04:20.560 as i said it's within the realm of possibility  that a larger earthquake will follow this one   00:04:20.560 --> 00:04:26.400 as is the case with any earthquake and is is  ultimately the case with even when earthquakes   00:04:26.400 --> 00:04:32.480 don't occur as we live in earthquake countries  so take this event especially if it whether it   00:04:32.480 --> 00:04:37.840 shook you hard or not take it as a reminder to  get yourself prepared for future earthquakes   00:04:39.520 --> 00:04:46.320 and visit the USGS website for up-to-date  information. I'm happy to take any questions that   00:04:46.320 --> 00:04:51.520 you have at the moment on any of this information  or other information you'd like to know.   00:04:53.440 --> 00:04:59.360 Okay thank you very much Austin this is Paul  Laustsen, again, um in the chat um there was a   00:04:59.360 --> 00:05:03.724 question from Tim Sheehan uh does the fault  have a name? 00:05:03.724 --> 00:05:10.480 [Austin] Yeah this is the Antelope Valley fault um and that's tentatively the name that we've given the earthquake the Antelope Valley   00:05:10.480 --> 00:05:17.120 earthquake although we recognize that the Antelope  Valley that's on the California/Nevada border is   00:05:17.120 --> 00:05:24.720 a very sparsely populated area and there is an  Antelope Valley in southern California that's much   00:05:24.720 --> 00:05:30.240 more populous nonetheless this is the fault  is the Antelope Valley fault um and so for now   00:05:31.040 --> 00:05:36.080 that's the relevant information. [Paul] Great thank  you very much Austin i'm going to unmute   00:05:36.880 --> 00:05:41.840 Ron Lin here in just a second i just wanted to  make sure you guys are looking at the chat um in   00:05:41.840 --> 00:05:48.320 the chat you will find uh a link to the earthquake  event page that has tons of information on it   00:05:48.320 --> 00:05:54.560 um including that aftershock forecast that Austin  uh spoke about so without further ado let me on   00:05:54.560 --> 00:06:00.160 you up Ron you're unmuted so go for it. [Ron] Hey this  is Ron Lin with the LA Times thanks for taking   00:06:00.160 --> 00:06:05.280 our questions. Two questions for you today, can  you talk about what you felt and where were you   00:06:05.280 --> 00:06:09.680 and assuming you're in the Bay Area can you  explain you know why some parts of the Bay Area   00:06:09.680 --> 00:06:15.840 felt it and other parts didn't like me in millbrae  and uh can you also talk more about the seismicity   00:06:15.840 --> 00:06:21.280 of the Walkerland System how often does it have  big quakes what's the maximum magnitude a quake   00:06:21.280 --> 00:06:26.240 can can hit there and is it a threat to places  like Mammoth Mountain and Lake Tahoe thanks so   00:06:26.240 --> 00:06:34.000 much. [Austin] Absolutely thanks for the questions Ron um  yeah i uh i felt the earthquake fairly strongly   00:06:34.000 --> 00:06:39.920 i'm in downtown San Francisco essentially  on a relatively high floor and i think that   00:06:39.920 --> 00:06:45.920 that may have um that certainly amplified  the experience compared to neighbors and   00:06:45.920 --> 00:06:50.000 other friends around me who did not feel the  earthquake. So there are a lot of reports of   00:06:51.600 --> 00:06:56.400 the earthquake being felt around the Bay  Area but it's probably not as widely felt as   00:06:57.200 --> 00:07:02.320 even one of the more local earthquakes that we  had for example last week on the Hayward Fault um   00:07:02.320 --> 00:07:09.440 which will be you know sharper and stronger  to people living near the epicenter. So this   00:07:09.440 --> 00:07:16.000 one because of its distance was probably more  perceptible in places that really amplify the   00:07:16.000 --> 00:07:20.080 the sort of slow distant waves and  so like the high building that i'm in.   00:07:21.360 --> 00:07:28.160 Um as with any earthquake there's also  amplification in soft soils, basin sediments,   00:07:28.160 --> 00:07:34.480 so if um if you're living on a bedrock hillside  or a ridge somewhere you're less likely to feel   00:07:34.480 --> 00:07:41.840 this same strength of shaking as people who are  uh living or working on in the flatlands basically.   00:07:42.560 --> 00:07:51.280 Um you're uh so that was the experience in the Bay  Area um certainly if you're in Reno, Carson City,   00:07:51.280 --> 00:07:55.440 uh some of the bigger places in Nevada, this  was a much stronger jolt um for you there   00:07:55.440 --> 00:08:00.880 and it but more than a jolt it's probably  a fairly good shake it was pretty alarming   00:08:02.880 --> 00:08:08.880 understandably so. Uh your second question was  basically how frequently how commonly earthquakes   00:08:08.880 --> 00:08:14.960 happen along here, and you know just in the last  year we've seen a fair number of earthquakes   00:08:14.960 --> 00:08:20.400 around this region and I think it's not  particularly uncommon, they're pretty   00:08:20.400 --> 00:08:25.520 representative, this is a classic place that  geologists go to study uh the active faults   00:08:25.520 --> 00:08:31.280 that we know formed the pretty dramatic topography  when you go east of the Sierra Nevada mountain   00:08:31.280 --> 00:08:40.560 range and through Nevada. So this is just  the latest among those there was another one   00:08:40.560 --> 00:08:45.920 last year you may remember the 5.9 Lone Pine  earthquake which happened farther to the south   00:08:46.560 --> 00:08:51.760 um in may last year there was amenities  6.5 a fair bit farther east in Nevada um   00:08:53.200 --> 00:08:57.680 there are quite a few examples spanning the  decades of these kind of magnitude five to six   00:08:57.680 --> 00:09:03.840 earthquakes uh happening in the eastern Sierra.  Certainly um so the fault that this happened   00:09:03.840 --> 00:09:11.840 on is essentially a small portion of the Sierra  Nevada frontal bounding fault system so it's what   00:09:13.120 --> 00:09:18.400 constitutes that massive majestic scarp  that you see if you drive up Highway 395   00:09:19.120 --> 00:09:27.680 um visiting places like Owens Valley, Bishop,  Mammoth Lakes, June Lake, all the way to Reno um and   00:09:28.800 --> 00:09:33.840 so this fault this was a small earthquake along  essentially that whole fault system and that's a   00:09:33.840 --> 00:09:38.640 very active structure it forms one of the highest  relief mountain fronts in the United States. 00:09:41.840 --> 00:09:46.640 [Paul] great thank you for the crescent question  Ron and just a reminder if you guys have   00:09:46.640 --> 00:09:49.200 had your questions answered then  just go ahead and lower your   00:09:49.200 --> 00:09:53.200 hand appropriately next uh Dale and  Dale can you please also let us know   00:09:55.120 --> 00:10:01.280 of course. hi uh Dale Castler Sacramento Bee  and sorry about the video I just like to   00:10:01.280 --> 00:10:07.280 call attention to myself i guess um and you  sort of touched on this a few minutes ago but   00:10:07.280 --> 00:10:14.400 I mean we're 200 miles away here in Sacramento we  usually don't feel earthquakes at all around here   00:10:14.400 --> 00:10:19.760 and everybody it's as if everyone around here felt  it. Was there something about this earthquake that   00:10:21.600 --> 00:10:24.800 for some reason it just  spread and spread and spread?   00:10:26.240 --> 00:10:32.080 [Austin] Yeah based on the measure well based on the  measurements that we have this is not out of   00:10:32.080 --> 00:10:37.200 the ordinary earthquake in terms of the shaking  intensities uh either instrumentally recorded   00:10:37.200 --> 00:10:43.360 or reported to our "Did You Feel It?" system based  on people's eyewitness shaking experiences.   00:10:44.080 --> 00:10:50.080 Um i think some things that may make this notable  it was a a fairly large earthquake and it's worth   00:10:51.040 --> 00:10:58.560 remembering that the magnitude scale is  logarithmic and every unit increase in magnitude   00:10:58.560 --> 00:11:07.680 is a 10 times an increase in the size of the  earthquake, um which ultimately means that a   00:11:07.680 --> 00:11:13.440 magnitude 5.9 earthquake shakes much more strongly  and has a much wider reach than many others.   00:11:13.440 --> 00:11:19.920 So other comparable examples to this one would  be things like the Monte Cristo earthquake last   00:11:20.480 --> 00:11:26.480 May um so a year and a couple months ago and I  think that was pretty widely felt although it   00:11:26.480 --> 00:11:31.760 was in the middle of the night so another factor  here maybe that it was at 3:30 in the afternoon   00:11:31.760 --> 00:11:39.040 a time when probably people are sitting around  awake attentive um a lot of people just at work   00:11:39.040 --> 00:11:46.160 basically um and were awake to perceive the  the way the waves from this large earthquake. 00:11:48.480 --> 00:11:56.800 [Dale] Okay thank you uh and if i could follow up in the  the Farmington quake that wasn't that was because   00:11:57.520 --> 00:12:02.720 in the initial ripple or the original initial  waves it was just misregistered as its own quake?   00:12:04.160 --> 00:12:12.480 [Austin] yeah essentially yes the um the ShakeAlert system  our instrumentation is sparse away from the large   00:12:12.480 --> 00:12:18.240 population centers and as you go farther into  Nevada and the ShakeAlert Early Warning system 00:12:20.560 --> 00:12:26.240 is structured to function for California so  this is on the mar this earthquake really   00:12:26.240 --> 00:12:34.800 occurred right at the margin of the operational  earthquake warning system uh and in an area with   00:12:34.800 --> 00:12:40.560 relatively sparse seismic instrumentation. So  what that means is that the initial magnitude   00:12:40.560 --> 00:12:44.480 takes a little bit longer to calculate may have  some greater uncertainty to it because there just   00:12:44.480 --> 00:12:50.240 aren't as many instruments there recording  it. What that means is that if an earthquake   00:12:51.200 --> 00:12:54.080 it's always a balance of speed if we're  trying to get early warnings out we want   00:12:54.080 --> 00:12:57.440 to determine the magnitude and location  of an earthquake as quickly as possible,   00:12:58.080 --> 00:13:03.440 but if you only have one or two stations uh  reporting you're going to have some on some   00:13:03.440 --> 00:13:08.480 rather large uncertainty in where exactly that  earthquake happened. So in this case the initial   00:13:08.480 --> 00:13:15.120 estimate of the location of the earthquake was a  few tens of kilometers off and that meant that as   00:13:15.760 --> 00:13:21.920 other stations registered the seismic  waves they actually registered them as   00:13:21.920 --> 00:13:26.240 a separate earthquake because they arrived  at an unexpected time compared to what our   00:13:26.240 --> 00:13:33.840 systems forecast the wave arrivals to how they  forecast the wave arrivals to reach the stations.   00:13:35.520 --> 00:13:40.800 [Dale] Thank you thanks very much. [Paul] Great thanks  Dale thanks Austin okay um next we have   00:13:40.800 --> 00:13:47.840 um Tim Sheehan uh and you please state your  affiliation uh let me make sure you're unmuted.   00:13:49.600 --> 00:13:56.640 [Tim] can you hear me okay? [Paul] Yep. [Tim].okay great yeah i'm with  the Fresno Bee uh one of Dale's colleagues uh   00:13:56.640 --> 00:14:03.840 with the company what I wanted to find  out is geologically is this area prone to   00:14:04.480 --> 00:14:07.280 you mentioned that this area is  not uncommon to see earthquakes   00:14:08.240 --> 00:14:13.520 I think in in way past history we're looking  at volcanic activity is there any reason for   00:14:13.520 --> 00:14:20.240 anybody to get worked up about you know the the  say the Long Valley Caldera as a result of this uh   00:14:20.240 --> 00:14:27.200 quake or is this just uh circumstance? [Austin] It's a great  question and we're talking about an area that in   00:14:27.200 --> 00:14:34.400 um the eastern Sierra the eastern California  is full of tectonic and volcanic features   00:14:34.400 --> 00:14:38.880 and activity. Uh the Long Valley Caldera,  Mammoth Mountain and the Ineo craters   00:14:38.880 --> 00:14:46.080 are a fair way south of where this earthquake  happened and so they're likely unrelated um   00:14:46.080 --> 00:14:52.960 to the to the event that we had this afternoon.  Furthermore what we saw this afternoon has a 00:14:55.200 --> 00:15:00.960 source mechanism that is consistent with motion  on a tectonic fault rather than having a volcanic   00:15:00.960 --> 00:15:08.400 source and so um in in that regard we have no  reason to expect that it has anything to do with   00:15:08.400 --> 00:15:16.800 the volcanoes that are a fair bit farther south of  it. Um and i i yeah i don't believe that there are   00:15:16.800 --> 00:15:24.720 any uh volcanoes or any volcanic activity that's  commonly registered anywhere north of that so this   00:15:24.720 --> 00:15:29.520 is quite reliably a tectonic earthquake and a fair  bit away from the active volcanoes that do exist.   00:15:30.640 --> 00:15:37.200 [Tim] Alright thank you very much. [Paul] Great thank  you very much Tim, um Amanda del Castillo   00:15:37.200 --> 00:15:41.520 could you please state your organization's  name and feel free to ask your question   00:15:42.480 --> 00:15:47.840 [Amanda] okay hello yeah i'm Amanda del Castillo with ABC  7 news here in the Bay Area wanting to know   00:15:47.840 --> 00:15:55.120 historically does the USGS in California report  more earthquakes during drought years? Thank you. 00:15:58.320 --> 00:16:01.760 [Austin] Thanks for the question Amanda that's  uh an interesting question and obviously   00:16:01.760 --> 00:16:07.040 one that will be on people's minds  considering the the confluence of   00:16:07.040 --> 00:16:15.920 the dramatic natural events that are going  on around us. I think it's unlikely that   00:16:16.880 --> 00:16:24.400 drought has any impact on the production of  tectonic earthquakes and we have not detected   00:16:24.400 --> 00:16:32.000 any substantial changes in the overall rates  of earthquakes uh in in recent years uh or   00:16:32.000 --> 00:16:37.520 any fluctuations over the decades so it's unlikely  that there's an observable effect at this point. 00:16:43.600 --> 00:16:49.840 [Paul] Okay thank you very much uh Austin. Are there  any other questions from the group here? 00:16:53.200 --> 00:16:59.360 Okay we will have a USGS feature story that will  go up on the main USGS website here pretty soon   00:16:59.360 --> 00:17:02.880 and we will keep our information  information updated there.   00:17:02.880 --> 00:17:09.840 I will try to post a recording of this call as  well for uh reference for your uh for stories   00:17:09.840 --> 00:17:17.360 um unless there's a larger unless there's a larger  event um we will not plan on taking more media   00:17:17.360 --> 00:17:24.240 inquiries uh this evening but you can go ahead  and send those to myself or Elizabeth Goldbaum,   00:17:25.760 --> 00:17:31.280 we can get those emails posted in the chat but if  you're looking for updates on the story we will do   00:17:31.280 --> 00:17:38.720 that in um on the USGS main page. Okay this is  your last chance to ask a question. [Austin] I may jump   00:17:38.720 --> 00:17:42.640 in and just make one little addendum which  i noticed just as i was beginning the press   00:17:42.640 --> 00:17:50.320 conference here the magnitude has of the main shock  at 3:30 this afternoon has been upgraded to a 6.0.   00:17:50.880 --> 00:17:54.960 Um that's nothing unusual nothing  to be worried about this happens   00:17:54.960 --> 00:17:59.520 as information comes in in the first minutes  and hours following an earthquake, magnitudes   00:17:59.520 --> 00:18:05.120 get refined and recalculated as more and more  seismometers report um and data is processed so   00:18:05.680 --> 00:18:10.240 uh in reporting for the stories that's the latest  magnitude you can always keep track on the USGS   00:18:10.800 --> 00:18:17.040 website um i just want to add that. [Paul] Yeah  that's huge, uh thank you very much Austin.   00:18:18.160 --> 00:18:24.800 Okay well thank you for everyone's um time and uh  we hope we won't be speaking to you anytime soon.   00:18:25.600 --> 00:18:30.400 Um well i'm, just in jest, you're always welcome  to call and reach out to us if you need   00:18:30.400 --> 00:18:39.142 something thank you very much for your time this  afternoon and thank you Austin. 00:18:39.142 --> 00:18:41.840 [Austin] Thanks everyone.