<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<div class="cal_8bf"></div>
<div class="cal_8bf">
<div>
<div class="x_cal_8476"></div>
<div class="x_cal_8476">
<div>
<div class="x_x_cal_e5f3"></div>
<div class="x_x_cal_e5f3">
<div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><b>Join us in person or online for tomorrow's seminar!</b></span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><br>
</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><b>Speaker:
</b>Chengrui Chang</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"> Department of Biomaterial Sciences</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"> University of Tokyo</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><b>Location: HYBRID (online and in-person at 1711 Illinois St, Golden, CO, Rm 204)</b></span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><b>Date/Time:
</b>Tuesday, December 20, 2022 10-11am MST</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><br>
</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px">Professor Chengrui Chang (U. Tokyo) will present the following two ~20 minute talks on the frictional behavior of an experimental fault zone and landslide movements.</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><br>
</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span class="x_ContentPasted0" style="font-size:16px"><b>Title #1: Frictional Properties and Structural Evolution of A Growing Experimental Fault Zone of NaCl Medium</b><br>
</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><br>
</span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:16px"><span class="x_ContentPasted1"><b>Abstract #1: </b>A key motivation of this study is to better understand the frictional behavior of a growing fault zone that develops
in granular medium. To this end, we employ a unique ring-shear configuration (Figure a) that has a large shear box (18 cm and 12 cm for outer and inner diameters, 10.9 cm for maximum sample height) to test a large volume of grains. Halite has been frequently
used as an analogue for fault gouge (e.g., Shimamoto, 1986; Noda and Shimamoto, 2010; Buijze et al., 2017). We use halite (NaCl) grains to simulate grain comminution. We vary the total normal stress from 0.2 to 1.0 MPa and keep the constant slip rate at 0.05
cm/s. We used two types of granular halite (NaCl) with different initial sizes. The coarse-grained halite was characterized by a particle size of ~2-5 mm while the fine-grained halite was of ~0.25-2 mm. It should be emphasized that a large experimental fault
zone is developed within the granular medium (Figures b-e).
<div class="x_ContentPasted1" style=""> <b><img data-imagetype="AttachmentByCid" explicitlogon="gs-ghsc-seminars@doimspp.onmicrosoft.com" data-custom="AAMkADUyYjhhNDdjLTM2ZjItNDU1YS04MzJiLTZiMzk5YzA1ZWQ3ZAFRAAgI2uIdI0UAAEYAAAAA%2BtEuMRRToUiWJiHM%2BXZQbAcA%2BNwATNGyGUiyQJkf%2FkWmOgAAAAABDQAA%2BNwATNGyGUiyQJkf%2FkWmOgACjvVf4QAAEAESABAAgWt3Y6S47UyBo2Lx6Aq4bw%3D%3D" naturalheight="0" naturalwidth="0" class="x_ContentPasted2 x_w-842 x_h-471" width="475" height="266" id="x_imageSelected0" size="322335" style="max-width:initial; width:475px; height:266px" src="cid:343c2f57-9c5c-43de-8b93-87f672ff7790"></b></div>
<div class="x_ContentPasted1" style="">The sheared medium is characterized by drastic grain fragmentation, which exhibits a higher friction coefficient over a slip followed by a substantial frictional weakening. We use a piecewise mechanical model to scale
the lengths of both the frictional stable and frictional weakening regimes and an exponential decay model to scale the length of compaction of the sheared medium. We find that all lengths are dependent on normal stress but only the scaling differs for compaction
length upon grain size. We propose that comminuted fines may serve as a frictional fluid and the weakening starts until shear zone is saturated by fines.</div>
<div class="x_ContentPasted1" style=""><br>
</div>
<div class="x_ContentPasted1" style=""><b class="x_ContentPasted3">Title #2: On the Slow-to-fast Transition of Landslide Movements and the Rate- and State-dependent Frictional Behavior in It</b></div>
<div class="x_ContentPasted1" style=""><b class="x_ContentPasted3"><br>
</b></div>
<div class="x_ContentPasted1" style=""><span class="x_ContentPasted3 x_ContentPasted4"><b>Abstract #2: </b>Slow moving landslides can sometimes accelerate to catastrophic failure (e.g., Lacroix et al., 2020). A series of phenomenological creep-failure models
have been established to describe the pre-failure acceleration that is commonly observed in landslide events and to achieve the goal of failure-time forecast of landslide, including Saito (1965, 1969), Fukuzono (1985), and Voight (1988) models. Among them,
the Voight model (Ω ̈=AΩ ̇^α) is more generalized for various forms of failure and natural phenomena, where Ω denotes an appropriate measurable quantity (e.g., surface displacement, titling angle), the dot refers to time derivative, and α and A are two empirical
parameters. It is, however, purely empirical and the relation between the parameters and underlying processes remains to be investigated. Particularly, the value of α is equal to 2 in the most landslides (e.g., Segalini te al., 2018), but it can be significantly
smaller (Bozzano et al., 2014). In addition, α can be different for different acceleration events in the same place (e.g., Crosta and Agliardi, 2003).
<div class="x_ContentPasted4" style="">Behavior of a tectonic fault is often modeled by a rate- and state-dependent friction law (RSF), which similarly shows diverse range of slip behavior. Here we investigate whether and how the RSF impact on the accelerations
that universally arise from the pre-failure stage of landslides. Helmstetter et al. (2014) applied RSF in a form of the aging law to a creep behavior of an underlying shear zone of landslides and showed α=2.</div>
<div class="x_ContentPasted4" style=""><br>
</div>
<div class="x_ContentPasted4" style="">We conduct creep tests on clayey soils in ring-shear configuration to reproduce the pre-failure accelerating movement. We suggest that the parameters in the Voight model change when shear localization sharpens acceleration
(Chang and Wang, 2022). We then establish interpretation of the creep behavior from the viewpoint of the RSF. We have mathematically shown that α = 2 naturally arise in many standard versions of RSFs, and α ≠ 2 and the change in α may be caused by time-dependent
loading conditions.</div>
</span></div>
<div class="x_ContentPasted1" style="font-weight:bold"> </div>
</span></span></font></div>
<div style=""><font color="#201f1e" face="Calibri, sans-serif"><span style="font-size:12pt; color:rgb(153,153,153)">For questions, comments, or speaker suggestions, please contact the </span></font><b style="color:inherit; font-family:inherit; font-size:12pt; font-style:inherit; font-variant-ligatures:inherit; font-variant-caps:inherit"><span style="font-weight:400"><span style="font-size:12pt; font-family:Calibri,sans-serif; color:rgb(153,153,153)">GHSC
Seminar Committee: Andrea Llenos <allenos@usgs.gov>, Benjamin Murphy <bmurphy@usgs.gov>, Lauren Schaefer <lschaefer@usgs.gov></span></span></b></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<span style="font-size:12pt"><b><br>
</b></span></div>
<br>
<div style="width:100%; height:20px"><span style="white-space:nowrap; color:#5F5F5F; opacity:.36">________________________________________________________________________________</span>
</div>
<div class="x_x_x_me-email-text" lang="en-US" style="color:#252424; font-family:'Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif">
<div style="margin-top:24px; margin-bottom:20px"><span style="font-size:24px; color:#252424">Microsoft Teams meeting</span>
</div>
<div style="margin-bottom:20px">
<div style="margin-top:0px; margin-bottom:0px; font-weight:bold"><span style="font-size:14px; color:#252424">Join on your computer or mobile app</span>
</div>
<a href="https://gcc02.safelinks.protection.outlook.com/ap/t-59584e83/?url=https%3A%2F%2Fteams.microsoft.com%2Fl%2Fmeetup-join%2F19%253ameeting_ZWI3OWFlOTQtZTVkZS00OGIzLTg3MzUtMThkMTgwMDI0Zjc5%2540thread.v2%2F0%3Fcontext%3D%257b%2522Tid%2522%253a%25220693b5ba-4b18-4d7b-9341-f32f400a5494%2522%252c%2522Oid%2522%253a%252250f012ff-efbf-4efc-b34b-d5361c4364e5%2522%257d&data=05%7C01%7Cghsc-seminars%40geohazards.usgs.gov%7C35b7193daa4e459646d408dae1dc8835%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638070634533467228%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=nHo8WlBlKOHL%2BH9ahYkeli8WkdhNunU5IxwbXooNMx8%3D&reserved=0" originalsrc="https://teams.microsoft.com/l/meetup-join/19%3ameeting_ZWI3OWFlOTQtZTVkZS00OGIzLTg3MzUtMThkMTgwMDI0Zjc5%40thread.v2/0?context=%7b%22Tid%22%3a%220693b5ba-4b18-4d7b-9341-f32f400a5494%22%2c%22Oid%22%3a%2250f012ff-efbf-4efc-b34b-d5361c4364e5%22%7d" shash="pm5gNQlQ09F+THLCT1r+FsHDuRwc9ubwuU8mZojqLqJPPepSN22+fqdVmRpRc6YTIuhp4jJzy32YiGk57ofpAuBlGVKL9VPhyv3SOVG5smfdFnYIWf3ho/Lr6UorxLRBZ/JGtKLBnLzkCkia6JjB+ki6LbsSZOy7FDbeKwmUnxw=" target="_blank" rel="noreferrer noopener" data-auth="NotApplicable" class="x_x_x_me-email-headline" style="font-size:14px; font-family:'Segoe UI Semibold','Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif; text-decoration:underline; color:#6264a7">Click
here to join the meeting</a> </div>
<div style="margin-bottom:20px; margin-top:20px">
<div style="margin-bottom:4px"><span style="font-size:14px; color:#252424">Meeting ID:
<span style="font-size:16px; color:#252424">276 852 793 971</span> </span><br>
<span style="font-size:14px; color:#252424">Passcode: </span><span style="font-size:16px; color:#252424">F6GHjw
</span>
<div style="font-size:14px"><a href="https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.microsoft.com%2Fen-us%2Fmicrosoft-teams%2Fdownload-app&data=05%7C01%7Cghsc-seminars%40geohazards.usgs.gov%7C35b7193daa4e459646d408dae1dc8835%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638070634533467228%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=Gqs25HEq%2BaxvQrKWEVdKvbWXqThUSzX3Uc396V%2FTOFg%3D&reserved=0" originalsrc="https://www.microsoft.com/en-us/microsoft-teams/download-app" shash="erwV/Y+kIHpATXElysqRUi3MQGIvA+SgT8WMZmIkVw2YVYQ8wq6KbK8A2z296yiVt+czkDXxxS6RPzHwtGAqjnT1aqV39U/01Qs1tEzjDjxireuvgxqyAdm0Lz0mHpnBsnGjZcdLEY+39k+SHSILshsz1c8exPyMHDYDIDB+piU=" target="_blank" rel="noreferrer noopener" data-auth="NotApplicable" class="x_x_x_me-email-link" style="font-size:14px; text-decoration:underline; color:#6264a7; font-family:'Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif">Download
Teams</a> | <a href="https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.microsoft.com%2Fmicrosoft-teams%2Fjoin-a-meeting&data=05%7C01%7Cghsc-seminars%40geohazards.usgs.gov%7C35b7193daa4e459646d408dae1dc8835%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638070634533467228%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=NEGnXL6z6MQzloVQ6YsbqED%2BvD0VuARq3zFFSopcLTM%3D&reserved=0" originalsrc="https://www.microsoft.com/microsoft-teams/join-a-meeting" shash="FLJATLTXuoCeAdK5fU7T6jG66hGEBLVhc5VcPL++9OfaV7O+1jI48ykgatgLaKSTbTuNsMae3CIL6y3NuLYLwSSiYOomywM8XpH97oa7nqz55HDOi+vpDNHx7cXP8mLrjrsmCkJ42odKHYjBF95xB99bEuuBntKN3OaYP6wtaU0=" target="_blank" rel="noreferrer noopener" data-auth="NotApplicable" class="x_x_x_me-email-link" style="font-size:14px; text-decoration:underline; color:#6264a7; font-family:'Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif">
Join on the web</a></div>
</div>
</div>
<div style="margin-bottom:24px; margin-top:20px"><a href="https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Faka.ms%2FJoinTeamsMeeting&data=05%7C01%7Cghsc-seminars%40geohazards.usgs.gov%7C35b7193daa4e459646d408dae1dc8835%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638070634533467228%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=muNl6YAFTfavtePagCpaoJGNdFoFYlKxkypkJClBoGM%3D&reserved=0" originalsrc="https://aka.ms/JoinTeamsMeeting" shash="PNYGl5G7lUok4pY26WiIJbT9hv41nuM3x7iCWEzIxKbGRPCBs27YyvxZ+KHhYRCXqti0jHQEoHKcFBw1j1NHxkcS2OLgHzGmzCrEHO0AmjmBAwGr/WZVAT0AIcP90UJqJ4v8FlzRrhLyrFWIy4K1cjs9EDD7w+qdyGXBOJElGgk=" target="_blank" rel="noreferrer noopener" data-auth="NotApplicable" class="x_x_x_me-email-link" style="font-size:14px; text-decoration:underline; color:#6264a7; font-family:'Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif">Learn
More</a> | <a href="https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fteams.microsoft.com%2FmeetingOptions%2F%3ForganizerId%3D50f012ff-efbf-4efc-b34b-d5361c4364e5%26tenantId%3D0693b5ba-4b18-4d7b-9341-f32f400a5494%26threadId%3D19_meeting_ZWI3OWFlOTQtZTVkZS00OGIzLTg3MzUtMThkMTgwMDI0Zjc5%40thread.v2%26messageId%3D0%26language%3Den-US&data=05%7C01%7Cghsc-seminars%40geohazards.usgs.gov%7C35b7193daa4e459646d408dae1dc8835%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638070634533467228%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=mSltenRvqUbPusyCcKgwO%2FF4GBiboFM4nkF36ovNhCo%3D&reserved=0" originalsrc="https://teams.microsoft.com/meetingOptions/?organizerId=50f012ff-efbf-4efc-b34b-d5361c4364e5&tenantId=0693b5ba-4b18-4d7b-9341-f32f400a5494&threadId=19_meeting_ZWI3OWFlOTQtZTVkZS00OGIzLTg3MzUtMThkMTgwMDI0Zjc5@thread.v2&messageId=0&language=en-US" shash="QO8lflMNCx5RyGxcP7M+aoXudelJI1lWcYfEf6ynnw3npfMuwudKrbmhN/lgz7D+uZ0LnmWT9Z4wtisgZYZuHCYdUFMug/GJSlSC6RO98y8h/1ViPkJqVsDqCFEfJgxpX87S8PsMdN76lnnL+PXtV7aIasVpN4stfFNjh1mtlW0=" target="_blank" rel="noreferrer noopener" data-auth="NotApplicable" class="x_x_x_me-email-link" style="font-size:14px; text-decoration:underline; color:#6264a7; font-family:'Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif">
Meeting options</a> </div>
</div>
<div style="font-size:14px; margin-bottom:4px; font-family:'Segoe UI','Helvetica Neue',Helvetica,Arial,sans-serif">
</div>
<div style="font-size:12px"></div>
<div></div>
<div style="width:100%; height:20px"><span style="white-space:nowrap; color:#5F5F5F; opacity:.36">________________________________________________________________________________</span>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>