It was only a matter of time: yesterday morning CENAPRED (Mexico's National Centre for the Prevention of Disasters) raised the alert level on Popo from yellow phase 2 to 3. This is the third highest warning on the seven step scale.

The Mexican newspaper, La Jornada reported almost a week of 'high amplitude tremors, with persistent emission of ash and gas that reached over 3.5m above the crater.' Incandescent fragments rising up to a kilometre high issue from Popo at present, where our team stood 5,000m up back in February. I ponder this as I type to you from the safety of the terracotta 'womb' of our beloved Museum.

Popo during quieter times in February. Dave, Chiara and Hugo survey their impending climb.

Who best to contact than Chiara, who knows more than most about the psychology of this restless giant? Following the recent activity of volcanic tremors and earthquakes she explained that, 'In the last couple of weeks, the dome has been destroyed. The caldera [a cauldron like feature, formed by the land collapsing after an eruption] is full to the brim and the fear is that lava may begin to flow outside the rim.'

There are currently no plans to evacuate but she said, ' The area within which you cannot go has been extended. At least until we know which of the two scenarios will now happen.'  By this, Chiara refers to Popo returning to a normal level of activity or continuing this temptestuous episode.

A letter to Popo. If you're going to erupt, don't do it without me. 

'It's very hard to tell what will happen at the moment. Popo is a very dangerous volcano.' It's here that despite being on the telephone in another part of the Museum, I sense that smile crossing her lips. The one I remember from our fieldwork in Mexico in February. ' I sent an article about this to Dave last week,' she continues, 'I told him what we need to do right now. Is to go back ...'

Watch this space to see how things develop!

Day five and we see a split in the team. The public engagement crew are town-bound due to our scientists traversing dangerous terrain at heights they've never been to before. I see the logic but I miss the buzz of the hike and reporting back first-hand. We travel as far as Tlamacas wth them at 06:00, me in the jeep asking them questions from UK students that are being relayed to me via phone, and all the while I'm eating a cheese and chilli sandwich. We're all tired but Dave and Chiara's day will push this exhaustion to its limit.

Still, it's vital to record their day for your good selves so I instruct Dave to take many photos, which you'll discover he was rather good at.

Popo, you never take a bad picture.

Rocky V: The return of the rugged outcrop. Actually, kinda like Stallone's face these days.

Chiara, Dave and Hugo cross a steep section of rocks roughly 30cm x 2m across, zig-zagging all the way. This in itself is tough going, those lungs in constant need of oxygen. But they're faced with an even steeper incline of pumice and loose ash after that and Dave gently laughs at the prospect. Slipping their way up, they are rewarded with reaching the snowline. A small patch of what once covered Popo to a greater degree, only to be reduced dramatically by the change in climate.

I'm fairly convinced this isn't a water stop. Hugo only stops to collect rocks.

The altitude sickness has lost it's bite for now and both Dave and Chiara are doing well. At least Dave can see straight away when he gazes up without the second or two delay he's been experiencing. Through his renewed vision, he spots a bread-crust bomb and as he photographs they hear a muffled, loud BOOM! The first explosion from Popo and I'm not there [shakes fist at sky]... A plume of gas drifts over the ridge and Dave remembers this isn't a mountain, this is an active volcano. And he's close enough to the crater to feel fear for the first time since being here.

The bread-crust bomb. Explain what it is or it'll break granny's teeth.

Meanwhile, I'd arranged to visit a local middle school in nearby San Pedro Nexapa to find out how the kids feel about living next door to Popocatepetl. The generous Gabriela and Gisela from the national park office had made this possible and as we turn into the gates I thank them. A sea of curious faces turn our way and I know from how they react we are in for a warm and funny visit.

Elsa, Marianna and Ana Paola had been chosen to speak with us and after shy introductions and a briefing that hopefully set them at ease, we set up camera. I didn't know what to expect as sometimes kids can be ambivalent to such real fears but the girls all showed it. They were more than aware from family members, the past dangers of Popo and, although very friendly, they were solemn on the subject. Marianna was particularly eloquent and agreed to appear with us on the live-link to the Museum's Attenborough Studio at 14:30 on Saturday (so check back with this blog as we hope that a recording of the event will be uploaded soon after).

Back to Popo and our scientists continue their climb ... the pumice under foot is 'Like standing on marbles' says Dave. Without poles? 'Nearly impossible.'

Two more BOOMS makes eight in the trek so far. Chiara, Dave and Hugo reach as far as they are going to climb today - 4,630m - where they'll take their first sample. They can see the stratification (arranging of layers) of the lava flows as they dip down into the valley.

Look at the strat on that.

The descent begins, back down to the snowline and Dave describes his footing as 'surfing the scree.' Much easier to slide down keeping the body stable than to scramble up it as he did earlier. He's keen to meet Chiara who's a little way off and make their way to the jeep after a 'cracking day.' Three or four more BOOMS in quick succession. Popo's really picking up the pace.

They descend further to 4,215m and feel the chill as the clouds descend. At an outcrop, they discover something new. A dark rock with really nice pink and white crystals of feldspar. Quite big crystals. They'd describe this as porphyritic and are both 'anxiously excited to find out why this rock is here and why it's different.'

The team made it back to base, safe and sound, despiite the frequent booms and rumbles that Popo made during their trek. Lee and I met them for dinner after a brilliantly guided visit by Gabriela to The Hacienda de Panoaya; home to a zoo, the international museum of the volcanoes, and a museum honoring Sor Juana Ines de la Cruz (Mexican nun and writer), who lived here during her childhood. Lee finished our visit in style with a post-lunch zipwire, crying out the word for 'mud' in Spanish to impress Gabriela with his learning.

It's Tuesday and Chiara's much better this morning as we live-link to host Ivvet and scientist Epi at the Museum for our first public Nature Live of the trip. Tamales (corn-based-dough steamed in a leaf wrapper) are on the way and we're all delighting in the semi-precious-looking hailstones that scatter the ground at the foot of Popo and it's neighbouring volcano Iztaccihuatl. Let's call it Izta, its less fun but easier.

Jealous of our Popo climb, another team prepare for Izta. The dogs wear neckerchiefs. A nice touch.

Today we explore a canyon and our hire car (no four wheel drives available) can only make it so far. We stop and jump in the jeep for a kidney pounding ride to where our hike will begin. Like the day before the terrain is rough. We follow a river and climb boulders, fallen trees, loose rocks and wet, shoe-swallowing sand.

Tamales. Don't hike for hours without one.

Midway to the end point of the canyon, I hear an almighty splash. A woman down. A hand outstretches toward me as I'm catching up fast. It's clutching a black object which is thrust into my hand. It's Chiara, having taken a tumble, choosing first to save her fieldwork notebook. Next is the smartphone and finally it's Chiara. Laughing, unhurt and undeterred she continues.

Chiara resists the urge to shower a la I'm a Celebrity.

I can see a change in the expressions of Dave and Chiara. These are good rocks. Really good rocks. We stop and the equipment comes out. Hugo and Dave explore the furthest part of what now appears to be a dyke.

You shin up that wet slippery trunk, I'll shoot.

A beautiful outcrop of lava. Chiara examines and collects.

Bright fungi nestle in fallen trunks.

Ever increasing his altitude, Hugo jumps down to join in the rock collecting. He agrees it's a fine bed of rock and grabs an appropriate hammer.

He'd make a mess of your Christmas nutbowl but Hugo can crack you a terrific rock sample.

As I stumble around attempting to look agile I spot our first insect of the trip. Entomologists please assist with this brightly coloured and handsome individual.

The team collect at many points back toward the jeep. A tiring hike but a very fruitful one. Silica-rich Dacite of a lovely quality. Also, on these cliff faces, where the river cuts-in, is a portion that interests them greatly.

Dave tells me it's where volcanic breccia meets andacite. For those of you new to geology what's exciting about these two rocks is how they've met. At some point after the magma has risen the breccia has been thrown out of the top and spilled out over the edge. Once they point this out, it's clear to see. You begin to feel the movement and energy of a now still material and see these different areas within one rock face. It's really very cool.

Breccia and andacite meet (just next to Hugo's foot)

We return to the jeep, picking thistles from our behinds like characters in a Warner Bros cartoon. There's discussion about an even more challenging day tomorrow.

Looming large is the 10 hour hike to our last outcrop on Friday. But tomorrow's not Friday and I put it to the back of my mind. We're a few days in and I'm keen to go through the samples with Chiara and Dave to find out how they are linked and what their first thoughts are of what they've found. How do they tell you about Popo's past? And how long before science can predict eruptions? Stay tuned.

By the time you read this I will be well on the way to the Popocatepetl, perhaps even there already... so while I and the rest of the team start preparing for the real work on the most active volcano in Mexico, here's the who's who of the Museum staff on this Field work with Nature Live trip. Let's start with the people here to do the fun stuff, the scientists:

Chiara Maria Petrone is Research Leader in Petrology, a branch of geology that studies the origin, composition, distribution and structure of rocks. In this role she leads the Museum research on active volcanoes and the generation of igneous rocks. What drives this research is to understand how active volcanoes work and to study the rocks to gain insight into their future activity. Likening her work to psychology, she strives to discover the hidden history of the volcano, from the initial magma formation and mineral crystallization till the final eruption.

She has a PhD in Igneous Petrology from the University of Florence, studied Mexican volcanic rocks as a post-doc fellow at the University of Kyoto (Japan) and at the Carnegie Institute of Washington DC (U.S.A) Since studying her PhD, Chiara has developed a wide knowledge of the volcanism of the Trans-Mexican Volcanic Belt, where Popocatepetl is situated.

Her C.V. is positively strewn with active volcanoes including Stromboli (Italy), Santorini (Greece), Vesuvius (Italy) and the Mexican Volcanic arc and she bravely giggles when one highlights the dangers of a volcano like Popo. It’s new to Chiara and she’s keen to climb and study it. Hers is a truly exciting journey to follow.

David Smith has a Masters in Geology and joined the Museum nearly 20 years ago. His official title is Petrology Collections Manager and he is responsible for the care and preservation of approximately 200,000 rocks and ocean sediments. Want access to material in the collection? Dave’s your man. The Museum’s Collections are in incredible order due to Dave’s deft curation but the work required on these vast numbers could keep Dave busy for another twenty years. And STILL not be completed.

Occasionally Dave appears on television showing specimens from historical expeditions and how they are used to enhance scientific knowledge today. The interest in the collection is not only from research scientists but artists too. Whenever he gets a chance, Dave likes to take photographs.

His subject interest is wide but he but prefers graphic architecture and abstract imagery. The latter I know because he first provided me with a blog photo you couldn’t see his face in. Once a year he teams up with three friends to form a rowing crew called 'The Muppets' for a Berkshire Regatta. Wearing the appropriate wig, Dave is 'Animal.' I cannot wait to see his fieldwork outfit.

And now your intrepid reporters:

Lee Quinn has been part of the special effects team at the Museum for seven years with an applied arts degree from Camberwell College and a BA in special effects from South Bank Uni. Specialising in audio, he provides the most entertaining of his own on work assignments with his animated chat and if you've ever visited exhibitions such as our Wildlife Photographer of the Year, you'll have heard the soundscapes he's composed too.

He'll not deny the idea of climbing an active volcano appeals to him, 'I bungeed off a crane in Orlando when they were first invented, so this is a natural progression for me!’

Lastly, I’m Jo Kessler your devoted blogger, camera-shy reporter and member of the Nature Live team at the Museum, blessed with the role of developing events with scientists and presenting them to public and school audiences. Whilst having a lifelong love of the natural world, I spent my first working decade in the music industry, representing hugely talented and inspiring role models. So, little has changed in that respect.

When volunteering at the Museum in 2005 (do it if you can, the rewards are endless) I completed a BA in furniture and product design but soon felt ‘the call of the wild’ and made natural science my career intead. I’m so excited by the science at the Museum my drive is to share it. So, bombard me with your thoughts and burning questions and they’ll be answered (volcano jokes notwithstanding) ...