Climbing and Trekking Semeru in East Java

Note: limitation of 600 trekkers/day in the national park. To find out more about the number of places still available for Semeru hike, click here.

Semeru, also called Mahameru, is a volcano that erupts since 1967 with the altitude of 3676m above sea level (highest point of Java island).

But you have some questions: how to climb Mount Semeru and reach its summit? From where should I start? How can I go to Semeru? When to go? How much will it cost? Where can I find the guides and porters? Where can I find camping equipment? What are the mistakes that I should avoid?

How is the climb? What are the stages of the hike?

Many questions without answers! And lots of time and efforts to do research and read the forums, blogs, and sometimes you find that the advises and commentaries are contradictory.

The purpose of this article is to give you the necessary information to climb Mt. Semeru and the mistakes you should avoid. Then, for those who don’t want some headache and want to delegate the organization and logistical tasks to Go Volcano, you’ll find the program and related price.

Finally, for the curious minds, at the end of this article we will talk about Mt Semeru, and the believes and the legends that surround this mountain. We will also talk about eruptions and volcanic activity of Mt. Semeru.

But before, here is a jaw-dropping video about Mt. Semeru :

9 things to know before hiking Mt. Semeru

How to go to Mt. Semeru?

The easiest way to go to Mt. Semeru is by passing through Malang (a city in East Java province) to Tumpang. Then from Tumpang ( 20 km eastward of Malang), you can take a jeep to high altitude village, Ranupani, in the foot of Semeru and from which the hike and climb will start.

Surabaya is the big city where Juanda international airport is located, from which the access to East Java will start. Then from this city you will go to Malang.

How to go to Tumpang and how much the transportation will cost?

From Surabaya

You can go to Malang by train, plane, bus, and of course taxi.

Taxi is the easiest option to go from Juanda airport in Surabaya to Malang.

• There are few shared taxi companies that will take you from the airport to Malang, and that will cost you about IDR 120.000,-/person. The only inconvenience is that you will have to wait for other passengers until the car is full. Please note that the final destination for most of the shared taxi companies is Malang city center. Thus, you will have to take another mean of transportation or taxi to go to Tumpang.
• Another option is by taking private taxi that will cost you about IDR 550.000,- to IDR 600.000,- per car for one way trip. The advantage is that the taxi can take you directly to Tumpang where you will take the jeep to Ranupani and Mt. Bromo.

By bus :

• You will find Bungurasih bus station in the south of Surabaya city, which is reachable by DAMRI bus from Juanda international airport for IDR 25.000,-/person. From Bungurasih, take an intercity bus to Arjosari bus station in Malang.
• To go to Tumpang, take a white minibus from Arjosari bus station. This minibus is locally called “angkot” or “mikrolet“. Let the driver know that you want to take TA (this is the direction code of the minibus), which stands for Tumpang – Arjosari. You will go until the last stop, which is a market, locally known as Pasar Tumpang. For accommodation and jeep reservation, you can go to Rani Homestay, located about 1.5 km from the market, or about 15 minutes of walk.

The land transport will take you about 3 hours (by private taxi) to 4 hours (by public transportations).

By train : it will take you about 2 hours to go to Malang, with limited service on economy class train, and you will have to add up the time to and from train station.

• From Surabaya you can take the train from Gubeng train station in the city center, Surabaya Pasar Turi in the north of the city, or Wonokromo in the south of the city. There is a small station called Waru that is located within short drive by taxi from Juanda airport. Then you can stop at Blimbing train station, walk for 300m towards Perempatan Blimbing (a big intersection), and take TA (the white minibus) to Tumpang. You can also stop at Malang train station and take a taxi for IDR 70.000,- to IDR 100.000,- to go to Tumpang.

From other cities :

By train : There are some trains that connect Yogyakarta and Malang that will take about 7 to 8 hours journey. The train is preferable than a bus since it’s faster, more reliable, and better in term of service. If you want to go to Malang city center, stop at Malang train station. You can check www.tiket.com or www.traveloka.com to check the train schedule and buy ticket online.

By plane: There are direct flights to Malang from Denpasar (Bali), Bandung, and Jakarta

Remark : If you have occasions to go to Malang directly either by train or plane, do it. The flight ticket is higher than the one to Surabaya, but you will save time on the road between Surabaya and Malang. You will be fresh and ready for the hike. And if you book the jeep in advance, they will be willing to pick you up from the airport in Malang to either Bromo or Ranupani.

How to go to Ranupani?

From Malang :

The jeeps are prohibited to pick up passengers from the train station. Thus, you’ll have to take a taxi from the train station to Tumpang (IDR 70.000,- to IDR 100.000,- per taxi)

• If you stay in a hotel in Malang, we can pick you up from your hotel for IDR 750.000,-/jeep/one way to Ranupani.
• We can also pick you up from the airport of Malang for IDR 750.000,-/jeep/one way to Ranupani.

From Tumpang :

• Jeep : IDR 650.000,-/jeep/one way (fits for up to 5 persons)
• Ojek / motorbike taxi IDR 200.000,-/motorbike taxi/one way
• Shared jeep for IDR 75.000,-/person. This option is only available on the high season (July-August), but you’ll have to wait until the jeep is full (10 to 15 people)

When to go to Mt. Semeru ?

Mt. Semeru is open between April to December or early January each year. There is no exact opening dates each year, thus we have to wait for further notice from the national park about the beginning of the hiking season.

How much does it cost the access to the national park?

Update on 2018 : The national park authority has applied the quota of 600 trekkers per day to enter the national park. Thus, there is high possibility that certain dates are fully booked. We suggest you to book the hiking permit quota in advance.

The entrance ticket is IDR 210.000,-/person/day during the week days, and IDR 310.000,-/person/day during the weekend. These tariffs for foreigners are 10 times more expensive than for locals!

Where to sleep?

• Malang offers every type of accommodations, ranging from a bed in dormitories to five stars hotels.
• Tumpang has limited offers. The best is Rani Homestay (1.5 km away from the market) where you can arrange transportation to Ranupani. They also offer hiking packages to Mt. Semeru and Mt. Bromo. Not to mention that the staffs speak English and French.
• Ranupani has limited offers of basic accommodations, ranging from dormitories to basic homestay.

Hiking Mt. Semeru : with or without guide?

Having a guide is not mandatory, but it is highly recommended. The beginning of the trails until the campsite is very clear. However, once you reach the pines forest right after the Kalimati base camp, things get more complicated. The summit attack is done at night, and it makes it harder to distinguish between the right and wrong path, as the path changes frequently due to erosion during rainy season. During high season, we might be able to meet many trekkers and hike with them. However, if you want to climb in peace and in your pace, having a guide is the best option.

Please also note that some people were lost and some have never been found. The luckiest ones were found several days after they got lost.

Where to find guide and porters?

The porters mostly are the farmers who live in the surrounding area of Mt. Semeru, thus Ranupani is the ideal place to find them. For the guide, it’s better to arrange in advance or find them from a homestay in Ranupani.

• Please note that they only speak local language and Indonesian language sometimes.
• The fee for an English-speaking guide start from IDR 500.000,-/day

Prices are there to give you information about the budget. It can be less than that, but it can be more as well. If you want to have experienced guides and porters, do not hesitate to contact us. We have some guides and porters who have been working with us since the beginning of our journey, so their experience and competence are proven.

Where to find camping equipment (tent, sleeping bag)?

There are several rental companies in Malang. However, the closest one is at Rani Homestay in Tumpang. Their tent and sleeping bags are in good condition and will cost you IDR 50.000,- per day for a set of tent, mattress and sleeping bag for 1 person. This option is preferable when you travel light. Don’t forget to book in advance as usually they are fully booked during high season.

Where to obtain the compulsory health certificate?

You have two options for that: You can go to a small hospital (Rumah Sakit Sumber Sentosa, Jl. Raya Kebonsari No. 221 Tumpang), or in a small clinic on the way between Tumpang and Ranupani.

The medical check-up will consist of measuring your weight, height, and blood pressure. It will cost you IDR 15.000,-/person, or about 1 USD.

Since 2018, there is a small clinic in Ranupani that can deliver health certificate for IDR 25.000,-/person. However, since it’s located in a relatively remote area, there is a chance that it is closed without precaution.

5 mistakes to avoid before and during the hike and climb of Mt. Semeru

1. Not to book the entrance ticket in advance
2. Coming without health certificate (your access to the hike will be refused)
3. Do the hike alone and not well informed
4. Coming during the period when the national park is closed (January to April)
5. Doing the hike without proper equipment. There were cases of hypothermia, and do not forget that Semeru is over 3500m high.

We have talked about the preparation before climbing Mt. Semeru. Now let’s talk about the hike itself!

Hiking and Climbing Semeru

First of all, is it dangerous to climb Mt. Semeru? Considering that it is an active volcano and in constant eruption.

After you read about the eruptions and activities of Mt. Semeru (in the last part of this article), you might think that it is dangerous to climb Mt. Semeru.

It’s not!

Most of the time, Mt. Semeru is not dangerous, especially since you will climb Mt. Semeru from the north side. Hiking Mt. Semeru from the south, contrary, is extremely dangerous, as well as approaching too close to the crater.

In the case of increased volcanic activity of Mt. Semeru, the national park will simply close and no hiking and climbing activities will be allowed.

In this chapter, we will explain how the hike will be, but first, we will put a hiking map of Mt. Semeru.

Hiking Map of Mt. Semeru

Starting from Tumpang

The journey will start from Tumpang, where you will take a jeep. About ten minutes drive away, you will see the beautiful farmland and you will pass through agricultural land comprising sugar cane, apple tree, vegetables, and oranges.

The higher you go, the closer you get to the jungle and the cooler climate. In some places the precipices are vertiginous. Extremely steep slopes. On the road, you can make a stop at Coban Pelangi waterfall (15000IDR / person), a waterfall that is unfortunately often ignored by tourists, while it’s a marvel and it’s on your way. The whole round trip walk will take you 30 to 60 min but it’s worth it!    

A little further, there is also the possibility of doing white water rafting (250000IDR / person). It is just for a small pleasure that can be done with small children as young as 6 years old. It is not a river with high -level rapids and can be a little shallow during the dry season. But in the end …. a picture speaks better than 1000 words.

Ngadas village

After observing the jungle and making several steep turns on the volcanic slopes, suddenly you will see Ngadas, a village of breathtaking beauty! Finally, you will see the fields of potatoes, cabbages, onions, and others on a vertiginous slope. It is really a magnificent sight and the photos never do justice on capturing how steep and deep the slopes are!

However, it is necessary to go early enough to have the best chance of seeing this beauty, because the haze and fog often come in the afternoon!

You will continue to Jemplang, from where you will have a magnificent view of the caldera of Tengger – Bromo.

Ranupani Village

From Jemplang, you will continue to the right to reach the village of Ranupani. Since 2018, the road has become rather good, and the Jeep is no longer necessary (But it is likely that you will take a jeep to get you to the village. A story of habit and security because there is not so long ago the road was in very bad condition).

Ranupani, a high altitude village from which one start the hike and climb to Semeru, is located at more than 2100m above sea level. With the company of a guide and the porters, you will cross a cloud forest for about 10km to the lake Ranu Kumbolo (about 3 hours).

Ranu Kumbolo Lake

Upon your arrival at Ranu Kumbolo lake, you will have a lunch break. Lunch will be prepared by guides and porters. You will only have to carry your clothes, your water for the day, and some snacks during the trip. The porters will take care of tents, sleeping bags, mattresses, water, and food.

After lunch at Ranu Kumbolo Lake, you will continue your route to an altitude savanna. This place is most beautiful at the end of the rainy season, between April and May (see when to go to Indonesia, JAVA). The savanna is full of life, green, and flowery. Later in the dry season the savanna takes on a silvery gold color.

Kalimati

To reach Kalimati (Located at the foot of Semeru at 2700m above sea level) from Ranu Kumbolo lake, you will walk about 5km (2h walk).

So far the hike is rather easy without big difficulties, unless when the weather is terrible.

As a flashback, during a previous climb, it had rained without stopping! The path in the cloud forest had become a field of mud. And some places had turned into small rivers. At other sloping places, it was almost impossible to neither go up nor down! It was a real toboggan and descents were done on the buttocks. We were wet from head to toe. In the savanna, the soil was better because it was sandy, but when the water did not fall above the sky, it came from plants and tall grass that wetted us even more!

Despite of this, those who arrived very early have had some luck, but also fear of hearing a big bang and seeing glowing reflections in the night from the lava. At sunrise, they had the chance to have a 10-minute break to see this breathtaking landscape from the summit. Not to mention that the explosions of the volcano this year were very impressive in term of level of the detonation, but less impressive in term of the level of the plume of smoke! And yes the volcano is alive and from year to year the eruptions are different!

I would say that the hike to Kalimati was rather simple. But it is from here that things can get challenging, especially in term of weather. And yes, it is over 2700m and it is very cold at night.

You can at least comfort yourself with a wonderful dinner prepared by the porters. Hot tea, soups, fruits, and real foods! What a luxury at this altitude at the foot of the volcano and in the middle of nowhere.

You can also see a beautiful starry sky or a bright moon if you are there at the time of the full moon.

As I said before, it is very cold but you will have to wake up at 1:00 in the morning. Turn on your head -lamp, take a hot tea, and hop! the real attack of the summit will begin!

The summit attack of Mt. Semeru

It is a steep hike! In only 3,5km you will have almost 1000m of elevation gain! These 3.5km will take you around 3h for the fastest.

But that’s not all. Once the pine forest has been passed, you will walk on a ground that is a mixture of ash, sand, gravel and volcanic rock. To make it short, for every 3 steps forward you will take 2 steps backward. You will have the impression that you don’t even move forward, especially as the cold, the wind, the dust, and the altitude will be your physical and mental enemies.

Semeru is not the highest volcano or the highest peak in Indonesia, as it is “only” 3676m asl, but it’s one of the most difficult ones.

If you are brave, full of perseverance, and when you finally reach the top … Wow! the reward is of sublime beauty. This volcano, these explosions, these plumes of ashes, this sunrise, this cloud sea, the summits, and the neighboring volcanoes are just breath-taking.

On sunny days when the atmosphere is clear and the clouds are low, you can see the Indian Ocean in the south and the Java Sea in the north. The mountains and volcanoes of Arjuno, Welirang, Kawi, Argopura, Raung, and even Bali and the island of Madura are visible from the top.

It should be known that this volcano starts from the sea at 0m altitude until 3676m. At the top, you will overlook the entire island of Java. You will see the Tengger Massif and Bromo. You can even see the red lava during explosions! (rather rare and only when it is still dark).

After all, this climb is really worth it and is not only to conquer oneself! It is the discovery and the experience of a raw beauty. Violent and beautiful at the same time.

It is a wonderful feeling. We feel the volcano, the mountain that is alive, growl, shake and finally explode in a plume of ash and smoke. We feel it all in our guts. It’s quite difficult to describe, but we must live it to understand. And then we will get hooked!

The Descent from Semeru to Ranupani

Now I’m talking to you about something nobody talks about! It is only after having savored this moment, this communion with the volcano, with this mountain, with this nature. After having felt very small and insignificant beside this giant of fire and sulfur. Well, we have to go back down to Ranupani!

It’s about 20km to go in the opposite direction and on the same road as on the way up.

And also a word about the local associations of students, Ikapala, the associations of nature protection, the Savers … They made a gigantic and remarkable work of cleaning the Semeru, raising awareness and awakening the consciousness to the nature protection.

Today, if Semeru is relatively clean, part of the credit is theirs.

Now you know almost everything about the hike and climb of Semeru. You probably want to do this hike but without the hassle! Below you will find the program and all the corresponding prices.

Hiking, Trekking and Climbing Semeru with “Go Volcano”

For those who want to climb and hike Semeru with us and delegate the management of logistics and organization, you can start here.

The highlights of the trip:

• Attend the regular eruption of an active volcano, Mt. Semeru (with the possibility of seeing lava)
• Panoramic view of East Java volcanoes
• Climb the highest volcano on the island of Java
• Hike to a beautiful volcanic lake

Prerequisites for Semeru hike

Age requirement: older than 10 years old (according to national park regulations) Good physical fitness and medical certificate (according to national park regulations)  

Semeru trekking and climbing trip 2 days 1 night

Duration: 2 days Price: from 125 € / 2,000,000 IDR Level: 4/5

Detailed Program and Itinerary

Day 1: Tumpang (600m above sea level) – Ranupani (2100m above sea level) Lake Ranu Kumbolo (2400m above sea level) – Kalimati (2700m above sea level)

You will have your breakfast at 6:30 am at your hotel, and you will go to a small clinic nearby to obtain a medical certificate (imposed by the authorities of the national park).

You will then go by jeep to Ranupani, the starting point of the hike. You will see the rainforest along the way and will cross the village of Ngadas, from where you can take a look at the top of the Semeru volcano. After this scenic drive, you will arrive at Ranupani. One of the highest villages in Java, at 2100m altitude.

From this village, you will take a path in the cloud forest for 3 hours to Lake Ranu Kumbolo (2400m above sea level), where you will have a lunch break.

After lunch, you will continue the hike for 2 hours to Kalimati base camp (2700m above sea level), where you will have dinner and camp for a night.

Accommodation: tent (1 tent for 2 persons) Meals included: Lunch, Dinner

Day 2: Kalimati (2700m above sea level) – Summit of Semeru (3676m above sea level) – Ranupani (2100m above sea level) – Tumpang (600m above sea level)

You will wake up at 00:30 to have coffee or tea and snacks before the summit attack of Semeru.

You will then walk on a very steep sand slope with almost 1000m altitude for about 4 hours for the fastest.

Once at the top of the volcano you will have a beautiful sunrise and a spectacular 360 degree view of East Java and of course the eruptions of the volcano at regular intervals.

Then you will go down to Kalimati (about 1.5 hours) or you will have a breakfast and a quick nap (in this part you have to be careful to follow the path, hikers and trekker have already lost!).

From there you will go to Ranu Kumbolo Lake for lunch (about 1.5h). After that, you will do the last 3 hours of walking to the village of Ranupani.

You will then reach the village of Tumpang by 4×4 jeep for an hour and a half.

Accommodation: – Meals Included: Breakfast, Lunch

Prices for hiking and trekking Semeru in 2 days 1 night

Do not hesitate to contact us should you have any questions, or to ask for quotes with chosen option, or to ask about departure date.

• For 7 people and more: from 2 000 000 IDR is 125 € / person
• For 4 to 6 people: from IDR 2 150 000 or 135 € / person
• For 3 people: from IDR 2,300,000 or 144 € / person
• For 2 people: from IDR 2,800,000 or 175 € / person

These rates include:

1. The services of an experienced English-speaking mountain guide all along the circuit.
2. Porters for camping equipment, water and food (1 porter / person).
3. Medical certificate.
4. Meals as indicated in the itinerary (4 meals).
5. Mineral water, snacks, and fruits during the days of hiking.
6. Non-conditioned 4WD jeep from Tumpang to Ranupani, round trip.
7. Camping equipment (1 tent / 2 people, sleeping bag, inflatable mattress, inflatable pillow, camping chair, toilet tent)

Not included :

1. Entrance ticket to the national park about IDR 230,000 (€ 14.50) / day/person on weekdays and IDR 330,000 (€ 20.50) / day / person on weekends and holidays (so count between € 29 and € 41 entrance fee to be added per person)
2. Hotel accommodation: We can book the following hotel rooms:
   • Rani Homestay (Tumpang): IDR 350,000 (€ 22) / room (2 persons per room) breakfast included (dinner or lunch on request: IDR 60,000 (€ 3.75) meal / person)
   • Hostel: price from € 5.50 in dormitories (several good addresses on Malang)
   • Luxury Hotel
3. Transport: We can book you the following transports:
   • Malang (station, airport, city center) – Tumpang: 6,25 € / vehicle (one way)
   • Surabaya (airport station, city center) – Tumpang: 47 € / vehicle (one way)
4. tips & personal expenses (drinks, souvenirs)
5. Air ticket
6. Travel insurance & assistance
7. Articles that are not mentioned in “included”

Prices for hiking and trekking Semeru in 2 days 1 night for solo travelers

For a solo traveler, we also offer the opportunity to climb the Semeru at a reasonable price from IDR 2,700,000 or € 169.

However, this trek will be done without a guide. But, you will have 2 porters speaking only the local languages.

It will also be your porters who will ensure your transport by motorcycle (as well as logistics).

Porters will take care of the logistics: food, water, gas and tools for the kitchen, tent, sleeping bag …

You will carry your clothes and your water of the day.

So this price includes:

1. 2 porters.
2. Medical certificate.
3. Meals as indicated in the itinerary (4 meals).
4. Mineral water, snacks, and fruits during the days of hiking.
5. Motorcycle from Tumpang to Ranupani, round trip.
6. Camping equipment (1 tent, sleeping bag, inflatable mattress)

Not included : Same as above

Semeru trekking and climbing trip 3 days 2 night

There is also the possibility of hiking semeru in 3 days and 2 nights.

Prices for hiking and trekking Semeru in 3 days 2 night

Do not hesitate to ask us your questions and to request price estimation with the options chosen and the dates by contacting us.

• For 8 people and more: from 2 800 000 IDR is 175 € / person
• For 4 to 7 people: from 3 000 000 IDR is 187 € / person
• For 3 people: from IDR 3,250,000 or 200 € / person
• For 2 people: from IDR 3 800 000 or 237 € / person

Go Volcano Tours including Semeru

Surabaya / Malang – Semeru – Bromo – Kawah Ijen – Banyuwangi / Bali => from 214 €, duration 4 to 5 days, Difficulty: 4/5.  

Other Go Volcano tours in East Java

Surabaya / Malang – Bromo – Kawah Ijen – Banyuwangi / Bali => from 105 €, duration 3 days, difficulty 1/5. Bali / Banyuwangi – Ijen – Raung  

Personal equipment that you should bring with you

Comfortable backpack with rain cover (25 to 30 liters). Sunglasses. Hat. Cap. Sunscreen or anything else that will protect you from the sun. Waterproof coat and/or windbreak. You will have to bring it to the top (it’s cold and windy). Headlamp. Hiking boots. Mask / scarf / multi-purpose mask. Hiking poles. Bottle of water

Clothing:

2 t-shirts 2 technical shirts 1 special hiking pants (especially no jeans) and 1 track-suit/tights for pajamas or overcoat. Warm clothes, a jacket, a fleece, a sweater. Gloves, hat and scarf. It can be very cold at the top socks (2 additional pairs)

Others:

Personal medications. We will provide a first aid kit, but please bring your own prescribed medication. Do not forget to bring your good mood ?

Note: This list is for reference only. You can add more equipment to suit your personal needs.

Special Requests for Event Planning in Tengger National Park Bromo Semeru

For all inquiries about the Semeru volcano and the activities you would like to organize (ie TV shooting, running, trail running and all other unusual requests, do not hesitate to contact us!)

We have already organized: the shooting of the Indonesian film 5 centimeter in 2012 – “Les Volcans de l’extreme“, an ultra trail on the 7 peaks of East Java in 2011, 2012, 2013 and 2014 – the shooting of the French program Echapées Belles in 2016 – and other being organized for the year 2018.

We will provide you with as much infromations as possible and we will contact the authorities of Tengger Bromo Semeru National Park and organize necessary permits.

In the near future, we will also list all the hikes and treks we offer around Semeru. (Off the beaten track but without climbing the volcano).

Now that all the practical aspects of the Semeru Climb have been mentioned. It’s time to talk about the Semeru volcano! so for the curious, below you will find a description of the Semeru, its volcanic activity, and its eruptions!

Mount Semeru or Gunung Semeru – Mahameru

The Semeru volcano is reputed to be a “safe bet” for volcanic activity in Indonesia. It produces a small volcanic eruption every 30 minutes or so. Indeed, the eruption that began in 1967 has been continuing uninterruptedly until today.

It is an explosive activity that is generally quite unimportant, oscillating between the Strombolian style and the Vulcanian style.

Mount Semeru, or Gunung Semeru in Bahasa Indonesia, is an Indonesian volcano, located in the province of East Java. It is the highest point of the Java island with 3,676 meters of altitude and 22 kilometers in diameter.

It is said to be the incarnation of the Hindu sacred mountain, Mahameru “The Highest Meru” (the other name of Semeru), sent to Java to appease the Indonesian islands that were suffering from instability. Its crater encloses the entire Hindu pantheon which also maintains links with other sacred volcanoes of Indonesian Hinduism: the nearby Bromo, the Agung in Bali, the Rinjani in Lombok.

The summit area consists of a plateau (Mahameru) which is the highest point, next to which is the active slag cone, Jonggring Seloko (the crater with a diameter of about 600 meters). these two points are separated by a valley oriented East-West, 50 meters deep. The crater of Jonggring Seloko is horseshoe-shaped open to the Southeast (we can see it in the video above).

Located south of the Tengger Caldera, Semeru is part of the largest volcanic complex in the East Java Province, grouped within the Bromo-Tengger-Semeru National Park and open to climbing between May and December (exact date to be confirmed for each year).

The eruptions of the Mt Semeru

Semeru is one of the 3 most active and dangerous volcanoes in the Indonesian archipelago. It is located in a densely inhabited area, Lumajang to the east, Pronojiwo, Tempeh, Pasirian to the South East and the big city of Malang (+1.5 million inhabitants) to the west.

In 1901, the city of Lumajang was destroyed!

The activity of the Semeru volcano can become paroxysmal, and generate imposing Vulcanian plumes, sometimes accompanied by pyroclastic flows and lahars.

Semeru eruptions in 1901, 1913, 1941, 1945, 1946, 1956 and 1967 were violent and projected eruptive material of more than 6000 meters high. Because of its altitude, we always are afraid of its lahars, which in 1981 caused 252 victims and destroyed 16 villages and 626 hectares of rice fields and plantations.

Since 1967 its explosive activity is regular and continuous. Medium-intensity explosions escape from one or the two of five mouths aligned in the bottom of the crater Jonggring Seloko, projecting eruptive material (blocks and ashes) at heights of 400 to 1000 meters, every 30 minutes or so. The bottom of the crater consists of a viscous lava dome that rises slowly.

A lava dome began a very active growth in 1967 until 1977. The lava dome completely filled the crater, then rose another 70 meters above the ridges. It is a period during which it was destabilized several times and generating pyroclastic flows which descend the South-East flank, as in 1974 when it traveled more than 7 km.

In 1977, a huge explosion shook the lava dome, projecting eruptive material between 6000 and 8000 meters high. The depth of the crater then drops down to about 300 meters.

In July 1990, the lava dome collapsed and formed a new crater about 700 meters deep, causing part of the volcano’s flank and creating a huge gap facing Southeast.

A new dome is installed. The volcano then resumes a typical activity with panache up to 1.5 km in height (August 1997), explosions, fiery clouds, avalanches of blocks and lahars. Gradually, following this regular activity, the bottom of the crater rises to be located in 2002 less than 200 meters from the edge of the crater.

On December 29, 2003, a pyroclastic flow took the Besuk Bang River and traveled more than 9 km until it stopped near the village of Supiturang, who was evacuated due to the risk of other pyroclastic flows.

The activity of Semeru is characterized by cycles of elevation followed by collapse and explosions that generate glowing avalanches, fiery clouds, and lahars. In 1990 the depth of the crater was about 700 meters, while in 1977, the altitude of Semeru went from 3676 to 3745 meters.

Map of risk prone areas of Semeru

The South-East flank is regularly subject to fiery clouds that sweep down the valleys of the Kembar and Kobokan rivers, during the rainy season, this ashy and unstable flank is also conducive to lahars (mudslides)

Eruption of Semeru in 1994

On 3 February 1994 observers from the Volcanological Institute of Indonesia (VSI) as well as people living near Semeru heard a thunderclap at 3:50 local time and then saw the fallout of ashes.

Lava avalanches and pyroclastic flows from the summit crater have descended the slope following the course of the Kembar and Kobokan rivers over a distance of 7.5 km and 11.5 km from the summit. Volcanic materials also affected the village of Sumberwuluh, located 8 km southeast of the volcano’s summit, between the two rivers.

Six people were killed, following lava avalanches and pyroclastic flows. 275 people were evacuated from Sumberwuluh, where many homes and 1.5 km² of plantations were destroyed.

The seismic station at VSI has also been destroyed.

The eruptive and seismic activity of the volcano increased at the end of 1993, with frequent collapses of the lava flow. Volcanic shocks had been recorded since October, with a peak on 25 December 1993. Permanent trenches of maximum amplitude 26 mm were recorded between 26 January and 3 February 1994.

Eruptive and seismic activity continued after February 23, but the intensity weakened. The daily number of explosive jerks reached 360 on February 5, 1994 and then dropped again, while remaining above 70 tremors a day in mid-February. Volcanic trenches were again recorded between 9 and 14 February with a range of 13mm.

The ash projections formed clouds that could rise up to 700 meters above the summit. Pyroclastic flows and avalanches of lava flowed for 3 km in the kembar and kobokan river beds. The lava extrusion from the crater overflowed the south lip to form a 750 meter long lobe, advancing on the south flank towards the Kembar River.

Conclusion

Semeru is a unique volcano, thanks to its regular eruptive explosions. Imagine yourself at the top, witnessing mini volcanic eruptions.

In addition, it is very accessible, even if the effort to do is far from negligible!

So what do you think of this article? Are there any questions I have not answered? Missing information?

I invite you to respond to this article in the comment section.

And to discover other active volcanoes!