# Blogs

## Not So Fast! Types of earthquakes at the Sumatra Seismogenic Zone

Several different types of earthquakes and fault-slip events happen at the Sunda subduction zone and other subduction zones around the world. Typical earthquakes usually last a few seconds to a few minutes, if they have very large magnitude. But not all fault slip results in typical earthquakes.

## Core description on land vs. core description at sea

The Chicxulub K-Pg Impact Crater expedition 364 scientists are in Bremen, Germany right now. They are describing the cores they drilled last spring in the Chicxulub Crater.

## The Sunda/Sumatra subduction zone- how does it compare to other subduction zones around the world?

What is a subduction zone?

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## Incoming! Oblique Subduction at the Sunda Subduction Zone

The Indian and Australian Plates plow northeast into the Sumatra subduction zone, part of the larger Sunda subduction zone, at a speed of 45 mm/yr. The angle between the direction these two plates move relative to each other is not always at a right angle (90°) to the subduction zone itself--here it is about 50°. Sliding under the Sunda Plate at an angle is not easy, so several large strike-slip fault systems help to accommodate some of this movement. If you thought learning vectors in high school was pointless—think again. This is a perfect vector component problem!

## The Earthquake that Triggered Expedition 362

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.

## Family portrait

We have 4 micropaleontologists on board during Expedition 362 who are working together to track the age of the core.

Meet our micropaleontology team! From left to right: Freya for Diatoms, Wen-Huang for Foraminifers, Jan for Nannofossils and Sarah for Radiolarians.

Why are we using microfossils?

## Daily Science Report Explained

Each day, our Staff Scientist/Expedition Project Manager sends out an update to the ship and to our colleagues on shore. The daily report summarizes the scientific findings from the day before. Here's an example of a daily report, explained with photos!

## How we drill and core in hard sediments and rocks

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When we want to drill into hard sediments and rocks, we have to change the drill bit. In the deeper part of Site U1480, we used an RCB (Rotary Core Barel) drill bit rather than the APC/XCB we used before for coring the younger, softer sediments.*