Evidence From High‐Resolution Topography for Multiple Earthquakes on High Slip‐to‐Length Fault Scarps: The Bilila‐Mtakataka Fault, Malawi
Geomorphological features such as fault scarps and stream knickpoints are indicators of recent fault activity. Determining whether these features formed during a single earthquake or over multiple earthquakes cycles has important implications for the interpretation of the size and frequency of past...
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| Veröffentlicht in: | Tectonics (Washington, D.C.) D.C.), 2020-02, Vol.39 (2), p.n/a |
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| container_title | Tectonics (Washington, D.C.) |
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| creator | Hodge, M. Biggs, J. Fagereng, Å. Mdala, H. Wedmore, L. N. J. Williams, J. N. |
| description | Geomorphological features such as fault scarps and stream knickpoints are indicators of recent fault activity. Determining whether these features formed during a single earthquake or over multiple earthquakes cycles has important implications for the interpretation of the size and frequency of past events. Here, we focus on the Bilila‐Mtakataka fault, Malawi, where the 20 m high fault scarps exceed the height expected from a single earthquake rupture. We use a high‐resolution digital elevation model ( |
| doi_str_mv | 10.1029/2019TC005933 |
| format | Article |
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<1 m) to identify complexity in the fault scarp and knickpoints in river profiles. Of 39 selected scarp profiles, 20 showed evidence of either multiscarps or composite scarps, and of the seven selected river and stream profiles, five showed evidence for multiple knickpoints. A near‐uniform distribution of vertical offsets on the subscarps suggests they were formed by separate earthquakes. These independent methods agree that at least two earthquakes have occurred with an average vertical offset per event of 10 and 12 m. This contrasts earlier studies which proposed that this scarp formed during a single event and demonstrates the importance of high‐resolution topographic data for understanding tectonic geomorphology. We use a one‐dimensional diffusion model of scarp degradation to demonstrate how fault splays form multiscarps and estimate the diffusion age
κt of the Bilila‐Mtakataka fault scarp to be
48±25 m
2, corresponding to
6,400±4,000 years since formation. We calculate that a continuous rupture would equate to a M
W
7.8±0.3 earthquake, greater than the largest seismic event previously recorded in East Africa.
Key Points
We use satellite topography and a numerical model to analyze normal fault scarps and knickpoints potentially reflecting multiple earthquakes
The Bilila‐Mtakataka fault, Malawi, shows evidence for two previous ruptures with 10–12 m of vertical offset each
The degradation of the scarps suggests a diffusion age of 48
± 25 m
2 corresponding to 6.4
± 4.0 Kyr since formation</description><identifier>ISSN: 0278-7407</identifier><identifier>EISSN: 1944-9194</identifier><identifier>DOI: 10.1029/2019TC005933</identifier><language>eng</language><publisher>Washington: Blackwell Publishing Ltd</publisher><subject>Diffusion ; Earthquakes ; Escarpments ; Fault lines ; Fault scarps ; Geomorphology ; Profiles ; Resolution ; Rivers ; Seismic activity ; Stream profiles ; Tectonic geomorphology</subject><ispartof>Tectonics (Washington, D.C.), 2020-02, Vol.39 (2), p.n/a</ispartof><rights>2019. American Geophysical Union. All Rights Reserved.</rights><rights>2020. American Geophysical Union. All Rights Reserved.</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-a4115-f8d28783ef00d477128b65a00b047766c739a0d152f7757ff7911260ee848fd93</citedby><cites>FETCH-LOGICAL-a4115-f8d28783ef00d477128b65a00b047766c739a0d152f7757ff7911260ee848fd93</cites><orcidid>0000-0002-0754-4110 ; 0000-0001-6669-308X ; 0000-0001-6335-8534 ; 0000-0003-3654-1637 ; 0000-0002-4855-039X</orcidid></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://onlinelibrary.wiley.com/doi/pdf/10.1029%2F2019TC005933$$EPDF$$P50$$Gwiley$$H</linktopdf><linktohtml>$$Uhttps://onlinelibrary.wiley.com/doi/full/10.1029%2F2019TC005933$$EHTML$$P50$$Gwiley$$H</linktohtml><link.rule.ids>314,780,784,1417,1433,11514,27924,27925,45574,45575,46409,46468,46833,46892</link.rule.ids></links><search><creatorcontrib>Hodge, M.</creatorcontrib><creatorcontrib>Biggs, J.</creatorcontrib><creatorcontrib>Fagereng, Å.</creatorcontrib><creatorcontrib>Mdala, H.</creatorcontrib><creatorcontrib>Wedmore, L. N. J.</creatorcontrib><creatorcontrib>Williams, J. N.</creatorcontrib><title>Evidence From High‐Resolution Topography for Multiple Earthquakes on High Slip‐to‐Length Fault Scarps: The Bilila‐Mtakataka Fault, Malawi</title><title>Tectonics (Washington, D.C.)</title><description>Geomorphological features such as fault scarps and stream knickpoints are indicators of recent fault activity. Determining whether these features formed during a single earthquake or over multiple earthquakes cycles has important implications for the interpretation of the size and frequency of past events. Here, we focus on the Bilila‐Mtakataka fault, Malawi, where the 20 m high fault scarps exceed the height expected from a single earthquake rupture. We use a high‐resolution digital elevation model (
<1 m) to identify complexity in the fault scarp and knickpoints in river profiles. Of 39 selected scarp profiles, 20 showed evidence of either multiscarps or composite scarps, and of the seven selected river and stream profiles, five showed evidence for multiple knickpoints. A near‐uniform distribution of vertical offsets on the subscarps suggests they were formed by separate earthquakes. These independent methods agree that at least two earthquakes have occurred with an average vertical offset per event of 10 and 12 m. This contrasts earlier studies which proposed that this scarp formed during a single event and demonstrates the importance of high‐resolution topographic data for understanding tectonic geomorphology. We use a one‐dimensional diffusion model of scarp degradation to demonstrate how fault splays form multiscarps and estimate the diffusion age
κt of the Bilila‐Mtakataka fault scarp to be
48±25 m
2, corresponding to
6,400±4,000 years since formation. We calculate that a continuous rupture would equate to a M
W
7.8±0.3 earthquake, greater than the largest seismic event previously recorded in East Africa.
Key Points
We use satellite topography and a numerical model to analyze normal fault scarps and knickpoints potentially reflecting multiple earthquakes
The Bilila‐Mtakataka fault, Malawi, shows evidence for two previous ruptures with 10–12 m of vertical offset each
The degradation of the scarps suggests a diffusion age of 48
± 25 m
2 corresponding to 6.4
± 4.0 Kyr since formation</description><subject>Diffusion</subject><subject>Earthquakes</subject><subject>Escarpments</subject><subject>Fault lines</subject><subject>Fault scarps</subject><subject>Geomorphology</subject><subject>Profiles</subject><subject>Resolution</subject><subject>Rivers</subject><subject>Seismic activity</subject><subject>Stream profiles</subject><subject>Tectonic geomorphology</subject><issn>0278-7407</issn><issn>1944-9194</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2020</creationdate><recordtype>article</recordtype><recordid>eNp90EtOwzAQBmALgUR57DiAJbYExo_ECTuoWkBqhQRhHbmN3biYOtgJqDuOAFfkJLgqC1YsPNZI3z8jDUInBM4J0OKCAinKIUBaMLaDBqTgPCli3UUDoCJPBAexjw5CWAIQnmbZAH2N3kytVnOFx9694FuzaL4_Ph9UcLbvjFvh0rVu4WXbrLF2Hk9725nWKjySvmtee_msAo5sE8SP1rQx3blYJmq16Bo8ljGAH-fSt-ESl43C18YaK6OYdvJZbt4WneGptPLdHKE9LW1Qx7__IXoaj8rhbTK5v7kbXk0SyQlJE53XNBc5Uxqg5kIQms-yVALMIHZZNheskFCTlGohUqG1KAihGSiV81zXBTtEp9u5rXevvQpdtXS9X8WVFWUZ4wRSnkd1tlVz70LwSletNy_SrysC1ebo1d-jR862_N1Ytf7XVuVoWFJCWcp-ALpPhsI</recordid><startdate>202002</startdate><enddate>202002</enddate><creator>Hodge, M.</creator><creator>Biggs, J.</creator><creator>Fagereng, Å.</creator><creator>Mdala, H.</creator><creator>Wedmore, L. N. J.</creator><creator>Williams, J. N.</creator><general>Blackwell Publishing Ltd</general><scope>AAYXX</scope><scope>CITATION</scope><scope>7TG</scope><scope>7TN</scope><scope>F1W</scope><scope>H96</scope><scope>KL.</scope><scope>L.G</scope><orcidid>https://orcid.org/0000-0002-0754-4110</orcidid><orcidid>https://orcid.org/0000-0001-6669-308X</orcidid><orcidid>https://orcid.org/0000-0001-6335-8534</orcidid><orcidid>https://orcid.org/0000-0003-3654-1637</orcidid><orcidid>https://orcid.org/0000-0002-4855-039X</orcidid></search><sort><creationdate>202002</creationdate><title>Evidence From High‐Resolution Topography for Multiple Earthquakes on High Slip‐to‐Length Fault Scarps: The Bilila‐Mtakataka Fault, Malawi</title><author>Hodge, M. ; Biggs, J. ; Fagereng, Å. ; Mdala, H. ; Wedmore, L. N. J. ; Williams, J. N.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-a4115-f8d28783ef00d477128b65a00b047766c739a0d152f7757ff7911260ee848fd93</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2020</creationdate><topic>Diffusion</topic><topic>Earthquakes</topic><topic>Escarpments</topic><topic>Fault lines</topic><topic>Fault scarps</topic><topic>Geomorphology</topic><topic>Profiles</topic><topic>Resolution</topic><topic>Rivers</topic><topic>Seismic activity</topic><topic>Stream profiles</topic><topic>Tectonic geomorphology</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Hodge, M.</creatorcontrib><creatorcontrib>Biggs, J.</creatorcontrib><creatorcontrib>Fagereng, Å.</creatorcontrib><creatorcontrib>Mdala, H.</creatorcontrib><creatorcontrib>Wedmore, L. N. J.</creatorcontrib><creatorcontrib>Williams, J. N.</creatorcontrib><collection>CrossRef</collection><collection>Meteorological & Geoastrophysical Abstracts</collection><collection>Oceanic Abstracts</collection><collection>ASFA: Aquatic Sciences and Fisheries Abstracts</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) 2: Ocean Technology, Policy & Non-Living Resources</collection><collection>Meteorological & Geoastrophysical Abstracts - Academic</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) Professional</collection><jtitle>Tectonics (Washington, D.C.)</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Hodge, M.</au><au>Biggs, J.</au><au>Fagereng, Å.</au><au>Mdala, H.</au><au>Wedmore, L. N. J.</au><au>Williams, J. N.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Evidence From High‐Resolution Topography for Multiple Earthquakes on High Slip‐to‐Length Fault Scarps: The Bilila‐Mtakataka Fault, Malawi</atitle><jtitle>Tectonics (Washington, D.C.)</jtitle><date>2020-02</date><risdate>2020</risdate><volume>39</volume><issue>2</issue><epage>n/a</epage><issn>0278-7407</issn><eissn>1944-9194</eissn><abstract>Geomorphological features such as fault scarps and stream knickpoints are indicators of recent fault activity. Determining whether these features formed during a single earthquake or over multiple earthquakes cycles has important implications for the interpretation of the size and frequency of past events. Here, we focus on the Bilila‐Mtakataka fault, Malawi, where the 20 m high fault scarps exceed the height expected from a single earthquake rupture. We use a high‐resolution digital elevation model (
<1 m) to identify complexity in the fault scarp and knickpoints in river profiles. Of 39 selected scarp profiles, 20 showed evidence of either multiscarps or composite scarps, and of the seven selected river and stream profiles, five showed evidence for multiple knickpoints. A near‐uniform distribution of vertical offsets on the subscarps suggests they were formed by separate earthquakes. These independent methods agree that at least two earthquakes have occurred with an average vertical offset per event of 10 and 12 m. This contrasts earlier studies which proposed that this scarp formed during a single event and demonstrates the importance of high‐resolution topographic data for understanding tectonic geomorphology. We use a one‐dimensional diffusion model of scarp degradation to demonstrate how fault splays form multiscarps and estimate the diffusion age
κt of the Bilila‐Mtakataka fault scarp to be
48±25 m
2, corresponding to
6,400±4,000 years since formation. We calculate that a continuous rupture would equate to a M
W
7.8±0.3 earthquake, greater than the largest seismic event previously recorded in East Africa.
Key Points
We use satellite topography and a numerical model to analyze normal fault scarps and knickpoints potentially reflecting multiple earthquakes
The Bilila‐Mtakataka fault, Malawi, shows evidence for two previous ruptures with 10–12 m of vertical offset each
The degradation of the scarps suggests a diffusion age of 48
± 25 m
2 corresponding to 6.4
± 4.0 Kyr since formation</abstract><cop>Washington</cop><pub>Blackwell Publishing Ltd</pub><doi>10.1029/2019TC005933</doi><tpages>24</tpages><orcidid>https://orcid.org/0000-0002-0754-4110</orcidid><orcidid>https://orcid.org/0000-0001-6669-308X</orcidid><orcidid>https://orcid.org/0000-0001-6335-8534</orcidid><orcidid>https://orcid.org/0000-0003-3654-1637</orcidid><orcidid>https://orcid.org/0000-0002-4855-039X</orcidid><oa>free_for_read</oa></addata></record> |
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| ispartof | Tectonics (Washington, D.C.), 2020-02, Vol.39 (2), p.n/a |
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| source | Wiley Online Library Journals; Wiley-Blackwell AGU Digital Archive; EZB Electronic Journals Library |
| subjects | Diffusion Earthquakes Escarpments Fault lines Fault scarps Geomorphology Profiles Resolution Rivers Seismic activity Stream profiles Tectonic geomorphology |
| title | Evidence From High‐Resolution Topography for Multiple Earthquakes on High Slip‐to‐Length Fault Scarps: The Bilila‐Mtakataka Fault, Malawi |
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