Chapter 11 — 2.4 Anak Krakatoa

Introduction to the islands and names:
Krakatoa was once a large volcanic island noted for a terrible eruption in 1883. Later, volcanic activity in the same area produced a new island that people named Anak Krakatoa, which means ‘child of Krakatoa’. The new island grew as lava and volcanic material built up over many small eruptions.

Where it is and how it looks:
Anak Krakatoa lies in the Sunda Strait, the sea between the larger islands of Java and Sumatra in Indonesia. It is smaller than many islands and has steep sides made of dark volcanic rock and sand. The top is a crater where steam, ash and sometimes lava can come out. Vegetation may grow on parts of the island between eruptions, but the surface keeps changing when the volcano is active.

How nature built the island:
Undersea eruptions bring up molten rock that cools and hardens. Over time, repeated eruptions add more material, layer upon layer. This process slowly raises the seafloor until an island appears above the water. Anak Krakatoa is an example of this slow building process happening after the 1883 destruction of the original Krakatoa island.

People and the island:
Fishermen, sailors and scientists all know the island. Local communities watch from nearby coasts because the volcano can be beautiful yet dangerous. The island is important for learning about how the Earth changes and for reminders about safety near seas and volcanoes.

Simple definition:
A volcano is a place on Earth’s surface where molten rock, gases and ash come out. Molten rock under the ground is called magma; when it reaches the surface it is called lava. Many volcanoes are found where Earth’s plates meet or where hot material rises from deep inside the Earth.

Parts of a volcano:
At the top is a crater, a bowl-like opening. A vent is a passage through which material moves to the surface. Below the ground there is a magma chamber, a store of melted rock. Channels join the chamber to the crater. When pressure builds in the chamber, the volcano may erupt.

Kinds of eruptions and effects:
Some eruptions are gentle, producing flowing lava that moves slowly and creates wide, low slopes. Others are explosive, sending ash and rock high into the sky and causing strong blasts. Explosive eruptions can be sudden and dangerous because they throw many hot rocks and ash that can bury places far away.

Underwater volcanoes:
When volcanoes erupt under the sea, hot material meets water and cools quickly, making new rock. If eruptions continue, the seafloor can rise and an island may appear. Anak Krakatoa formed this way over years of submarine eruptions that built up a cone until it reached above sea level.

Why scientists watch volcanoes:
Experts measure small earthquakes, gas, ground movement and temperature to know when an eruption may come. These signs help warn people. For volcanoes near the sea, a collapse or underwater explosion can make a tsunami, so monitoring is important to protect lives and homes.

What happened in 1883:
The 1883 Krakatoa eruption was one of the most powerful volcanic events in modern history. Over several days the island produced loud explosions and thick ash columns. The force of the explosions destroyed much of the original island and sent dust high into the atmosphere.

Immediate effects:
The eruption produced very large waves — tsunamis — that struck coastal villages on nearby islands. Many homes, boats and people were swept away. Sound from the explosions was heard hundreds of kilometres away. Ash fell over wide regions, darkening the sky and covering crops and houses.

Wider consequences:
The ash and dust reached the upper atmosphere and spread around the globe, affecting sunlight. This caused short-term changes in temperature and colourful sunsets for months. Shipping and trade in the region were disrupted, and many communities lost livelihoods for a time.

Formation of a new island later:
Because so much of the original Krakatoa was destroyed or submerged, volcanic activity continued under the sea in the same area. Over years, new eruptions built up material that formed a new volcanic cone above the sea surface. This new cone eventually became Anak Krakatoa.

Lessons from history:
The 1883 eruption shows how sudden natural forces can have local and global effects. It taught governments and scientists about the need to study volcanoes and to prepare warning systems for coastal communities.

Summary of the event:
In December 2018 Anak Krakatoa had a strong eruptive phase. Small to moderate eruptions occurred over days. Then part of the volcano’s flank (its side) collapsed into the sea. This sudden collapse displaced a large amount of seawater and caused a local tsunami that reached nearby shores quickly.

How it affected people:
The tsunami struck at night in some places, when people were asleep or on beaches. Many people were injured, and a number lost their lives. Boats, houses and tourist facilities on beaches suffered damage. Rescue teams from nearby towns worked to reach survivors and to recover those who died.

Why warnings were limited:
Although volcano monitors had noticed activity and local authorities issued warnings about volcanic danger, the specific hazard of a fast flank collapse producing a tsunami was not widely expected. Tsunami-warning systems often rely on sea-floor sensors and earthquake detection; a sudden volcanic collapse can happen too fast for some systems to give effective local alerts.

Response and investigation:
After the disaster, scientists used satellite images, tide records and eyewitness reports to study how the collapse produced waves. Governments reviewed their monitoring systems to include better local alerts linking volcanic activity with possible tsunamis. The event underlined the need for clear local evacuation plans and public education about all signs of danger, such as water receding or loud noises from the sea.

Basic explanation:
Tsunamis are large water waves caused by sudden movement of a large volume of water. While many tsunamis begin with earthquakes, volcanic events can also cause them. The key idea is sudden displacement: something changes quickly under or near the sea and pushes water out of its normal position.

Common volcanic causes:
1) Undersea eruptions: When a volcano erupts beneath the sea, explosive force can push water upwards. If the eruption is strong and rapid, the water column above the eruption can form waves. 2) Volcanic landslides or flank collapse: Part of a volcanic island can break off and fall into the water. This rapid mass movement forces water away and creates waves. 3) Pyroclastic flows entering water: Hot ash and debris moving quickly into the sea can displace water and form waves.

How wave size and speed change:
Near the source, waves may be very high and energy is concentrated. As waves travel, the energy spreads across a larger area and wave height usually decreases, but the waves can still be dangerous far from the source. Tsunami waves can travel fast in deep water and slow down and grow taller as they approach shallow coastal areas.

Local versus distant tsunamis:
A local tsunami — one caused close to shore — can arrive within minutes, leaving little time to evacuate. Distant tsunamis travel across oceans and may give higher warning time. Volcano-related tsunamis at places like Anak Krakatoa are often local, so quick local action and evacuation to high ground are essential.

Prevention and warnings:
Monitoring volcanoes, sea-level sensors and public education about natural warning signs (strong shaking, loud sea noises, sudden sea retreat) help reduce harm. Combining volcanic monitoring with local tsunami alert systems improves readiness.

What is an eyewitness report?
An eyewitness report is a short account told by someone who saw or felt an event. In stories about Anak Krakatoa, fishermen, residents and rescue workers often give such reports. These reports describe sounds, times, visible signs like smoke or waves, and actions people took.

Why eyewitness reports are useful:
Reports give immediate detail that instruments may not capture. They help build a picture of what happened, especially when events are quick. Scientists and rescuers use these accounts together with records from instruments and satellite images to make a complete story of the event.

How to read them carefully:
First, find facts in the report: words that tell what, when and where (for example, 'I heard a loud bang at night' or 'The water pulled back'). Second, note feelings and opinions separately: words like 'scared' or 'terrible' show emotion but are not facts about timing or size. Third, compare different reports: if many people say the same fact, it is likely accurate.

Activities to practise:
Given two short eyewitness reports, list the facts from each and mark common points. Ask: Who said it? Where were they? What did they describe first? Next, rewrite a report in three clear fact-sentences using past tense. This helps students move from reading to accurate writing.

Using reports in class and tests:
When asked to summarise an eyewitness account, keep the facts in order: what happened, where and when, and one sentence on impact. This teaches careful reading and clear expression, important skills for exams and real-life understanding.

Why vocabulary matters:
Knowing the right words helps you read stories, answer questions, and speak clearly about events like the Anak Krakatoa eruption. Each word carries a specific meaning; using it correctly makes your writing and speaking stronger.

Key words and simple meanings:

• Volcano — an opening in the Earth's surface that can let out lava, ash and gases.
• Eruption — when a volcano releases lava, ash or gases.
• Crater — the bowl-shaped top of a volcano.
• Tsunami — a series of large sea waves caused by sudden movement of water, often from earthquakes or volcanoes.
• Collapse — when part of something falls in or breaks down quickly, such as a volcano’s side.
• Ash — fine particles of rock thrown into the air during an eruption.
• Magma — molten rock under the ground; becomes lava when it flows out.
• Lava — magma that reaches the surface and flows as hot liquid rock.
• Eyewitness — a person who saw an event happen and tells about it.

How to learn and use these words:
Make short sentences with each word, then try to use them in a short paragraph about the 2018 event: for example, 'The eruption threw ash into the air. The collapse caused a local tsunami.' Use the words when answering questions and in class talks. Practice matching words to meanings and filling blanks in sentences to build confidence.

Classroom activity idea:
Make a two-column table: left column words, right column meanings. Cover the right side and test yourself by writing meanings from memory. Then swap and write example sentences for each word.

What is the main idea?
The main idea is the central point that the writer wants you to know. In a short passage about Anak Krakatoa the main idea may be that a volcanic collapse caused a tsunami, or that volcanoes can be both interesting and dangerous. Finding the main idea helps you answer questions correctly.

Steps to find the main idea:
1. Read the whole paragraph once for a general sense. 2. Look for repeated words or phrases — these are clues. 3. Ask, 'What is the paragraph mostly about?' Try to say that idea in one simple sentence. 4. Underline one or two sentences that give important facts supporting the main idea. These are supporting details.

Types of supporting details:
Supporting details can be numbers (dates, counts), descriptions (sounds, colours), examples (eyewitness comments) or results (damage, rescue). Good readers separate the central point from these supporting items and then combine them into a short answer or summary.

Practice method:
Take a short paragraph and cover the last sentence. Ask students to write what they think the main idea is, then compare to the author’s closing. Another method is to make a two-column note: left side the main idea in one sentence; right side three supporting facts. This trains clear thinking and prepares students to write short answers in exams.

Exam tip:
When a question asks for the main idea, keep your answer short—one sentence. To show you understand, add one or two supporting details but do not copy long parts of the passage.

What is a summary and why write one?
A summary is a short, clear version of a longer text. It keeps the main idea and the most important supporting points but leaves out small details, examples and personal feelings. Writing a summary shows you can understand and express the central facts of a passage.

Steps to write a good summary:
1. Read the passage carefully and find the main idea. 2. Underline the key supporting facts such as dates, places and results. 3. Write a first sentence that gives the main idea (what happened). 4. Add one or two short sentences with the most important support (where, when, who was affected). 5. Finish with a short consequence or lesson (for example, need for warnings).

How to keep it short and clear:
Use simple language and avoid copying long parts of the text. Stick to three to five sentences for a short summary. Use past tense when you write about past events: 'The volcano erupted. The collapse caused a tsunami.'

Practice exercise:
Take a short eyewitness paragraph and try to write a two-sentence summary aloud. Then write it down and compare with a partner. Swap summaries and see if your partner can tell the main events from your writing. This helps you practise clarity and correct tense use for tests.

Exam tip:
When asked to summarise in an exam, plan quickly: find the main idea in one minute, note two key facts, then write. Keep sentences short and check verb tenses before handing in your paper.

Why we use the past tense:
Events like the 1883 and 2018 eruptions happened in the past, so we use past tense verbs to tell about them. Using the correct past tense shows the time of action and makes stories clear to listeners and readers.

Simple past forms:
For regular verbs, add -ed to make the past form: talk → talked, watch → watched. Many common verbs are irregular and must be learned: go → went, see → saw, have → had. In sentences about Anak Krakatoa you will often use simple past: 'The volcano erupted.' 'Waves hit the shore.'

Past continuous for background actions:
Past continuous (was/were + verb+ing) describes actions that were happening when another event occurred. Example: 'People were sleeping when the waves arrived.' The past continuous gives the scene and the simple past gives the main event that happened in that scene.

Questions and negatives in the past:
For questions use did + base verb: 'Did they hear the sound?' For negatives use did not (didn't) + base verb: 'They did not expect a tsunami.' Note that the main verb stays in base form when you use did.

Practice tasks:
Change present-tense sentences to simple past: 'The island grows' → 'The island grew.' Make past-continuous sentences: 'They run to safety' → 'They were running to safety when the water arrived.' These exercises help you write clear event descriptions for exams and classwork.

Purpose of oral practice:
Speaking about Anak Krakatoa helps students organise thoughts, practise vocabulary and communicate facts clearly. It is useful for class presentations, group discussions and answering oral questions in exams.

Structure for a short talk (about one minute):
1. Opening sentence: say the when and where (for example, 'In December 2018, Anak Krakatoa erupted in the Sunda Strait'). 2. Cause sentence: give the main cause or action (for example, 'Part of the volcano fell into the sea'). 3. Event sentence: describe what happened next (for example, 'The collapse caused a tsunami that hit nearby coasts'). 4. Effect and safety sentence: state the result and a safety point (for example, 'Many were injured; we must move to higher ground when such danger appears').

Useful linking phrases:
Use connectors to make your speech flow: 'because', 'then', 'after that', 'as a result', 'therefore'. For example: 'Because the volcano collapsed, waves formed and hit the shore.' These simple connectors help listeners follow the sequence of events.

Practice tips:
Speak slowly and clearly. Use short sentences and the vocabulary learned in this unit. Practice with a partner and time your talk. Ask friends to give one short suggestion: speak louder, slow down, or use one more detail. Try to include one eyewitness fact to make your story real, such as 'people heard a loud bang'.

Class activity:
Prepare a one-minute talk and present it to the class. Then answer one question from the teacher. This exercise builds confidence and listening skills for others.

Connecting facts with feelings:
When we read about disasters like the Anak Krakatoa tsunami, we learn facts and also meet real people who felt fear, loss and hope. Understanding these feelings helps us respond kindly and to think about how communities can recover. Empathy means paying attention to other people’s emotions and offering helpful support.

Recognising emotions in reports:
Eyewitness accounts often mix facts and feelings. A sentence like 'I was terrified' tells how someone felt. Other sentences describe actions caused by feelings, such as 'We ran to higher ground.' Learning to name emotions — scared, sad, relieved, thankful — helps students discuss the human side of disasters clearly.

How to show care in small ways:
Simple acts can help survivors: giving warm clothes, helping carry water, or listening kindly are meaningful. In class, students can write a short letter of sympathy or prepare a list of things a family might need after losing a home. These activities teach practical compassion and teamwork.

Classroom role-play and discussion:
Role-play helps students practise polite questions and offers of help: one student acts as a survivor and another as a volunteer. Practice phrases like 'I am sorry for your loss' or 'Can I help you with water?' After role-play, discuss what actions were most helpful and why. This builds language and social skills together.

Long-term community help:
Empathy also means thinking how a community can rebuild. Discuss simple ideas: planting trees, helping rebuild homes, sharing food, and teaching safety. These conversations make students aware of real civic responsibilities and encourage them to act with kindness when disasters happen.

Purpose of practice exercises:
Exercises test reading, vocabulary and grammar learned in this unit. Regular practice improves speed and accuracy for school tests. Exercises also help students form clear, short answers under time limits and build confidence for oral questions.

Types of exercises and how to do them:
1) True/False with correction: Read a sentence and decide if it is true; if false, write the correct version. This trains careful reading and attention to detail. 2) Matching words with meanings: Match vocabulary like 'eruption', 'ash' and 'crater' to simple meanings; this helps memory. 3) Fill-in-the-blanks with past tense: Use the correct past form to complete sentences about the 2018 event, for example 'The volcano _____ (collapse) into the sea.' 4) Short answer questions: Answer 'What happened?' or 'Why did the tsunami occur?' in one or two sentences to practise concise replies. 5) Summary writing: Write a three-sentence summary of a short paragraph to practise choosing main points and using past tense.

Sample exercise sheet and timing:
Part A: Read a short passage (5 minutes). Part B: True/False (5 minutes). Part C: Match words (5 minutes). Part D: Fill in the blanks (7 minutes). Part E: Two short answers and a two-sentence summary (8–10 minutes). This totals about 30–35 minutes and imitates classroom test conditions.

Peer review and marking tips:
Work in pairs to check answers. For True/False corrections, partners should explain why a statement is false. For summaries, swap papers and highlight the main idea to see if it matches. Teachers can use simple marks: + for correct, √ for good use of vocabulary, and a short note on tense errors to help revision.

Extra practice at home:
Read a short news paragraph about a natural event and do the same exercise routine. Keep a small vocabulary notebook with five new words from each lesson and write one sentence for each word every day. Regular short practice is more useful than long last-minute study.

Project purpose and choices:
For this project students choose between making a safety poster or writing a short report about Anak Krakatoa and tsunami safety. The aim is to combine facts from the unit with clear language and simple design so others can learn and act safely.

How to make a poster:
Use a large sheet and plan the layout: title at top, a central drawing of the sea and island, arrows showing movement to higher ground, and three short safety rules at the bottom. Choose a clear headline like 'Move to Higher Ground' or 'If the Sea Withdraws, Run Upwards'. Keep text short and use bright colours for visibility. Add one short sentence explaining why the action is important, for example, 'Waves can come quickly after a volcanic collapse.'

How to write the short report (120–150 words):
Start with one sentence saying what Anak Krakatoa is and when the 2018 event happened. Add two sentences describing the cause (eruption and collapse) and the immediate result (tsunami and damage). End with three short safety rules in bullet form or as separate sentences and a closing sentence about helping survivors. Use the past tense for the event and vocabulary from the unit.

Assessment and teamwork:
Teachers will look for correct facts, use of vocabulary, clear past tense for events, and overall neatness. Groups of two or three can work together: one student draws, another writes, and the third prepares a one-minute oral explanation to present in class. This helps weaker students and builds team skills.

Presentation tips:
Practice a one-minute explanation of the poster or report. Speak clearly, use at least two vocabulary words from the unit, and end with one safety advice sentence. Display posters around the classroom or school to raise awareness.