You can get more that you bargain for doing a Geology PhD – a story of earthquakes and volcanoes

Cora McKenna is doing a PhD on basaltic lava flows and magma intrusions: a fascination that led her to contemplate a hike up Mt. Rinjani, the central valcono on Lombok, Indonesia. Things didn’t go according to plan, here is her story….

In June my mother and I travelled to Indonesia to visit my brother and his wife and meet my new-born nephew for the first time. As part of the trip we decided to abandon the bustling city capital, Jakarta, and travel to the picturesque island of Lombok for a week’s holiday. We stayed in the coastal resort of Senggigi, about 20 minutes from the capital of Lombok, Mataram. Senggigi is a known for its west facing beaches (both white and black sand to suit all tastes) and as the gateway to the idyllic Gili Islands.

What was missed. the summit caldera of Mt Rinjani at 3,700 m with the new emerging cinder cone from the last significant eruption (Source: http://griyasari.com)

What was missed. the summit caldera of Mt Rinjani at 3,700 m with the new emerging cinder cone from the last significant eruption (Source: http://griyasari.com)

My brother and I had more adventure than relaxation in mind when picking the island of Lombok as we intended to trek to the caldera lake of the 3,700 m stratovolcano that dominates the landscape of Lombok, Mount Rinjani. After 3 days of discussions with local guides, however, sensibility overcame adventure and we reluctantly considered that perhaps a 3-day trek with camping through dense jungle, high altitudes and a 30 degree temperature drop was not overly suitable for a new born baby. On June 22nd we told our small group of our decision to stay on the coast as a family for the time being over a fantastic lunch in Senggigi, all the while looking forlornly at the clouds hiding the spectacular volcano from view. At 13:40 (CIT) we announced we could not visit one of nature’s greatest spectacles. At 13:42 one came to us.

We were standing to pay for our lunch and admire the works of local artists displayed on the walls of the restaurant when suddenly the world became to shake violently. I was reminded of being on research vessels during storms as my vision went from ground to ceiling to ground again against my will and in the three seconds it look my brain to connect the dots that this was an earthquake, it was already over. The thing that surprised me the most was the noise: the sound of rocks grinding against each other or perhaps concrete moving. It was like being inside a large pebble mill. Having watched many videos of earthquakes I knew what to expect from the ground and furniture moving but the noise took me by complete surprise, it really does not come across on film.

Lombok Island, with the distinctive Mt. Rinjani to the north, and Senggigi (blue star). The original epicentre reported on the 20 June (yellow star) and revised epicentre (red star marked)

Lombok Island, with the distinctive Mt. Rinjani to the north, and Senggigi (blue star). The original epicentre reported on the 20 June (yellow star) and revised epicentre (red star marked)

Once the shaking had stopped everyone rushed outside into the courtyard for the safety of open space. The locals explained to us that it was the biggest they had felt in two years and their fear was more of incoming tsunami than falling buildings; a rule of thumb in the region is that magnitude 6 or above off the coast will create the devastating waves. This is the real fear the people of Indonesia face in the wake of the 2004 disaster. To their experienced eyes this quake felt big enough. Luckily however it was quickly reported as a being magnitude 5.2 earthquake (or 5.4 by some sources) and the only thing to follow were a few tiny aftershocks.

That afternoon, the epicentre was pinpointed to the coast off of the Gili islands, a revised epicentre in the following day’s shows that it was in fact just off the west coast of Lombok, a few kilometre from where we were enjoying our lazy lunch in the sun. The earthquake originated at a 10 km depth.

Thankfully there was no loss of life as a result of this earthquake, however at least 5,289 houses were damaged, and 49 people have been reported injured (5 seriously) as a result of falling buildings. 27 houses of worship, consisting of 15 mosques, 10 temples and two monasteries were damaged at various extents. At least 6 villages were affected in total. Many people in the affected area lost all of their belongings and all of their food supplies are buried beneath the rubble. This area is mainly farmland or soft soil. One has to understand also that this area of the island is very rarely hit by such strong earthquakes, which means that the (mostly brick) older houses and infrastructure have not been constructed to withstand strong earthquakes.

The Local Lombok Regional Disaster Management Agency, West Nusa Tenggara, are working hard with local people in the affected villages but they need all the support they can get. As is sadly often the case with natural disasters, it is the poorest people in the region that have been most affected, many of whom have lost everything. Lombok relies heavily on tourism, and I would urge anyone reading this that if you cannot give to the RDMA, then consider Lombok as a future holiday destination. Events like this are rare but it is a beautiful tropical island, filled with kind and generous people 365 days of the year.

Geofon seismogram of the main quake and some minor aftershocks, and extent of affected area from earthquake-report.com

Geofon seismogram of the main quake and some minor aftershocks, and extent of affected area from earthquake-report.com

I asked the non-geologists in our group to describe the experience from their perspective:

“A deep rumbling sound and feeling. After a second obviously from the ground. Sank in it was an earthquake. People stood still. Locals knew what it was, had experienced it before. When it was finished everyone walked outside, but locals more distressed afterwards. Had been 2 years since they experienced one near this level and they were worried tsunami would follow as they know that a magnitude 6 could form tsunami and this felt about that big in their experience. A visiting geologist said a tsunami would have arrived by this stage. She seemed delighted by the experience…..”

Rina McKenna, of Athlone, Ireland

“The ground shook and there was a big roar, locals ran before we figured out what was going on. There was a certain amount of creaking in the restaurant we were in. Before running I shielded the baby’s buggy by closing the cover – in retrospect probably not the most useful thing against a falling building!”

Ian McKenna, 30, of Jakarta, Java

“very, very scary”

Kartika Sari, 30, of Jakarta, Java

“meh, it was no singing kettle” (translated courtesy of Ian and Tika)

James Javas Nararya McKenna, 4 months, of Jakarta, Java

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