Author: aredanz3

March 18^th would be our last deployment of the field campaign! This would be carried out by Samer, Marino, Alexa, and Kennet who would first head to recover on the gulf island of Chira. Meanwhile, Olivier, Anna, and Gabriel would go out and recover a site . Our day was relatively easy but with a lot of driving. The other team sent news of the data from Chira being great. This was a huge relief since we didn’t have an option to leave it any longer! They then headed out for the last deployment of the campaign.

After we picked up our site, we spent the remainder of the day washing and packing up the equipment for our departure the next morning. Bringing soil across international lines is not something we want to be charged with, and most of our equipment was covered in it. We half-packed the cars so that we would still be able to recover the remaining sites the following morning.

The morning of March 19^th would be the last bits of fieldwork: we would be splitting into 2 groups early in the morning and each group would recover a site and then return to the hotel to pack up and head out before the check-out time of 11 am. Oliver, Anna, and Alexa went to recover the site with the nice family who lived in the mountains. After our recovery, we stopped by for a quick goodbye, but they had already prepared breakfast for us and insisted that we stay. They even made lots of delicious plantains because I had mentioned they were my favorite!

We had the most amazing homemade cheese and natilla with our breakfast and after they walked us around a tour of the neighboring properties. We all made sure to get a picture together before heading out. The other group arrived at the hotel shortly before us and now it was time to clean up and pack up.

We had the most amazing homemade cheese and natilla with our breakfast and afterwards they walked us around on a tour of the neighboring properties. We all made sure to get a picture together before heading out.

On our way out of the Nicoya peninsula, we would be dropping Kennet off at his family’s home so that he could stay with them until it was time for his flight back to the U.S. We obviously took a group photo.

After our second farewell of the day, we headed to do a quick recovery, and shocker, we took yet another group photo to commemorate our final recovery of the campaign!

After a month spent on the Nicoya peninsula, the team would finally be heading back to San Jose! This is where we began the real portion of the drive, with around 4 hours ahead of us. After dealing with intense traffic and some extreme mountain roads, we finally made it, and we dropped Gabriel off at his home on our way to San Jose.

We said only a temporary goodbye as we knew he would be joining us for the team party the following night. Alexa and Oliver had flights leaving on the 21^st of March and so we only had a day left before having to say our farewells. Alexa is from a smaller city outside of San Jose and would be staying with her family for two nights while Oliver, Samer, and I would be staying at La Casa Universitario (this is the sister hotel of the gorgeous first hotel we stayed at when we arrived in Costa Rica what seems like so long ago…).

Alexa’s family graciously hosted the farewell party and all the members of our team, past and present, were invited. Our hosts were so accommodating and made the most delicious meal. 

Carlos, his wife, Gabriel, and his family, Alexa, Oliver, Anna, Samer, Luis, and David were all able to attend! It was so amazing to have almost everyone together to celebrate a job well done! All in all, we successfully installed 43 sites over a month! Amazing work by everyone. So many holes were dug!

The dinner was fantastic, and our hosts were the absolute best. As we were talking about the successes of the project and plans for the data, we suddenly felt the ground start to shake! A table full of geologists and geophysics and we were feeling the effects of a far-off earthquake! Not more than 20 minutes prior we had been discussing how I was the only one at the table who had never felt an earthquake before. It was a nice send-off to highlight the importance of the work we were doing in the country.

When the party drew to a close, we had to say our actual goodbyes. Alexa would be flying back to Nebraska and Oliver would be flying to Atlanta. Luis and David would be heading back to their homes in San Jose and would resume their schooling at the University of Costa Rica. Samer and I would be staying in Costa Rica for an extra week. Samer would be embarking on a much-needed vacation and I had a week-long solo trip planned. This was a bittersweet end to a fantastic month in the field! We are all tired and ready for life to get back to normal but it’s always sad to say farewell to the field crew, especially when your crew was as showstopping as ours .

We are excited to see what our data show and how this can be used to better understand fluids and earthquake hazards on the Nicoya Peninsula. The next steps are to return home and work on data analysis and modelling to build upon the wealth of knowledge about the peninsula. We are so thankful to all the people who helped make this field season a success, especially the gracious landowners and caretakers. Thanks for coming along for the ride on this blog!

March 16^th brought with it the excitement of deployment on yet another island! We would be heading to Chira, the largest island in the Gulf of Nicoya! This was again done by the early risers of Kennet, Oliver, and me. The other team would be going off to recover the station we had deployed near the hotel in Nicoya. Kennet grew up in the town nearest to the boating dock, meaning he knew the local fisherman well and because we would be traveling by boat, Kennet was an integral part of this. Our boat to the island left on schedule at 8:30 am, we were told we would be picked up by tractor when we arrived on the island. As a trade deal, we brought 3 containers of diesel fuel with us to fuel the tractor portion of our mission.

This island has no access other than by boat, so gasoline was a hot commodity, especially for farmers on the island.

When we arrived on the island, we were greeted by two farmhands and a tractor with an attached trailer for cattle transport. Our small team of three and our equipment would ride in the cattle compartment. After transferring the equipment to the trailer, we began chugging along to the site at tractor speed.

 This island was much larger than the others which means we were able to get far enough away from the island’s powerlines. Deployment went quickly and the two farm hands shared some local fruit with us that grew in the field. They also went by motorcycle and brought us cold soda! The flavor is called cholita and is local to Costa Rica the only place you can get this flavor in the U.S. is at the World of Coke in Atlanta, Georgia. It is bright pink and tastes slightly like bubblegum.

After we finished up, I checked the voltage on the battery and to my shock, it had a low power level of 12.6V, this was a bad sign. Battery issues had been on the rise recently as the campaign drew to a close. The initial decision to rent the batteries rather than buy them new was coming back to haunt us. While renting seemed more appealing financially and convenience-wise, it has stabbed us in the back here and there, this being one of those times. Some of the batteries won’t hold a charge and fail quickly even when they read as fully charged. If the battery failed, the whole trip to the island would have been for nothing.

Lucky for us, there was a local mechanic on the island who would be able to sell us a shiny new battery, all we had to do was get there. By tractor, it would take around 20 minutes and require lots of precious diesel fuel, but by motorcycle, it could be a quick and fuel-efficient trip. It was decided that I would be sent off with one of the farmhands to facilitate the battery purchase.

My rudimentary Spanish and understanding of car batteries did the trick, and soon we headed back to the farm to get the tractor to head to the site to replace the no-good, rented battery.

 We were thrilled, the site was a success! The absolute kindness of the people of Chira was something we were so thankful for, these farm hands and the farm owner who had never met us were willing to drop everything to help us ensure that our site on the island would work out. Everyone we’ve met on our fieldwork journey through the Nicoya peninsula has been nothing but hospitable and friendly, the people of the Gulf islands were no different. We made a note to bring them extra diesel fuel as a thank-you when we returned for the recovery.

Once the battery issue was solved it was time for a farewell, we shoved off the dock after profusely thanking the two farm hands for all their help. The clouds on the way back were stunning.

The remainder of our ride was smooth and we managed to spot a crocodile hanging out near the sides of the river.

I ate a ripe mango provided by Kennet in celebration of a job well done!

Even with the battery issue we finished early and had some downtime to relax!

The progress after March 16th:

On March 14^th we would be redeploying a station. This was because the former station in that region yielded data that was much too noisy to use. While this was a little annoying, it is also the only site we have had to do this for thus far, which is a really encouraging sign. Given that the last site in this area was a bust, I would be running a test run at this site to ensure history wouldn’t repeat itself. The other team had scouted this site, so we all made the drive together, in caravan formation, and then split up once we arrived. The other team of Samer, Gabriel, and Kennet would be making the treacherous journey down to Arío, which is where the truck got stuck just a day prior. We were nervous for them but knew it was a job that needed to be done.

We finished our installation as quickly as possible because today it was not only sweltering hot but also extremely humid because of the imminent rain showers. Today was another race against the storm clouds, we would finish this installment and rush over to Hojancha for the recovery of our semi-permanent site (the one with the gorgeous tree). After the installation and test run, we did just that, the drive would be an hour and the rain looked like it was moving quickly. The long bumpy dirt road to the permanent site would become an easy place for us to get stuck in mud if the rain beat us there. After yesterday’s events where Samer, Gabriel, and Alexa were struggling to get out of the mud for 3+ hours, we had a heightened fear of repeating history.

Unlucky for us, we were just about tied with the clouds, and as soon as we arrived, thunder rumbled through the sky.

We recovered in record time motivated by the fear of getting stuck or struck by lightning. We rocketed back down the bumpy dirt road, setting a record for the fastest drive made by our fieldwork party.

In celebration of no one getting stuck, we ended this day with a stop at Pops for some ice cream treats, which has quickly become a team favorite, and even got to enjoy a gorgeous sunset!

Progress after March 14^th:

 On March 15^th we would be splitting into a team of three and a team of two; Kennet had some work to get done but we devised a plan to manage without him. Each team would deploy one station, while the team of three would be recovering one as well.  Then we would all reunite to deploy a third station together. Gabriel and Samer headed to install one station and Alexa, Oliver, and Anna did the same for the other station.  Thanks to Alexa’s handy work getting us permission the night prior, the landowner of our deployment site generously allowed us to deploy anywhere on his large property.

Next, we headed to recover the site we deployed in Vigia on the day we changed hotels, this had lots of gates, but we managed to finish up and head back to the hotel by 2 pm.

After reuniting with Samer and Gabriel, the five of us ate a quick lunch and then drove off to our last deployment of the day, which would be done as one team. This deployment was an interesting one, we had to trek through a field of tall grass to reach a flat area where the ground was grey and cracking. To top off this eerie scene, the storm clouds were rolling in fast, and as soon as the first hole was dug we started to hear thunder. This meant we had to hurry.

The looming storm made this deployment a little bit of a stressful one. Once we finished the installation (or so we thought), most of the team headed back to the car while Samer and Alexa checked the resistance values on the electrodes. We do this at every site to ensure that the receiver is working properly and that every sensor is properly connected and recording signal. At this station, it’s a good thing we checked because one of the electrodes had really high resistance, indicating an issue with its connection. Samer isolated the problem to the west electrode and/or its cable. After around 20 minutes of troubleshooting in the rain, it turned out that the issue was with the cable. We replaced the cable and were finally on our way. This was a long day for both teams and after dinner, we quickly headed to bed.

Progress after March 15^th:

March 12^th was a laid-back day for both teams. Oliver, Kennet, and I went to do a quick morning installation while the other team would focus on scouting some locations for the more difficult areas in the southern portion of the peninsula. We installed the receiver in a recently tilled field, meaning the holes practically dug themselves! We were done in under an hour and headed back to the hotel to wait for word on the potential second site of the day. At around 2 pm the other team (Alexa, Samer, and Gabriel) returned with permission for a coastal site just a short walk from the beach in the town of Arío, which would be installed the following day. To make use of the remaining daylight, Gabriel, Kennet, Oliver, and Samer headed out to scout for another site in the mountains near the town of Rio Frio, and hopefully have enough time left to complete the installation before dark. Luck was in the air that day, as they did exactly that! Overall, a straightforward and productive afternoon. The following day would not promise the same.

We would be switching hotels again, leaving behind our hotel in Còbano and returning to the hotel El Regalo in Nicoya. We would also have to pick up the sites on Caballo and Cedros Islands. This is where things get complicated, it would be Monday, and school on Caballo began at 7 am (recall that the site was located in a schoolyard). This meant we would have to arrive on the island at 6:30 am to pick up the station and beat the crowd. With the hour-and-a-half drive and the 30-minute boat ride this meant that the crew of our teams’ early risers (Oliver, Kennet, and I) would need to leave around 4:30 am just to be safe.

Progress after March 12^th:

At the crack of dawn on March 13^th, that’s exactly what we did. We headed out on time and after managing only one wrong turn we made it to the dock! The timing was in our favor this time around since it was high tide which meant we didn’t have to trudge through the muddy riverbed again. The boat driver met us at the dock, and we shoved off for a surprisingly cool sunrise boat trip.

Picture of the boat ride

The boat ride was pleasant, and the recovery was as well, the walk to the boat for this recovery is short, giving us a gentle start to the day. On the boat ride back, the sons of the driver joined us again! This time I had brought my watercolor set to paint the sky, I extended an invite to the boys and they both joined me. This was the most relaxing start to a day in the field thus far.

Upon arriving back at the dock we loaded up and hurried to the next recovery making it to the ferry for Cedros Island by 8:20 am.

 We were making good time and got word of another successful recovery done by the team of late risers (Alexa, Samer, and Gabriel) when they picked up a mainland site on the eastern end of the peninsula. After this, the island recovery team (Oliver, Kennet, and I) tackled the strenuous recovery on Cedros in around 45 minutes, putting us back at the port around 10 am. Once all the recoveries for the day were completed, each team began to scout for more sites within the areas of their respective recoveries. However, the island recovery team’s scouting quickly proved to be a dead end. The area we intended to deploy was a steep valley with lots of powerlines and large water pumps ( both are major sources of noise for MT data). We decided this area may have to be left as a gap in our grid and we moved on to deploy in a town called Vigia, which was conveniently on the way to the hotel in Nicoya. By this time, it was around 2 pm, meaning the team of early risers was bordering on a 10-hour workday. This also meant we were all exhausted and cranky. Just as we arrived at the deployment site we received a progress—or  I guess I should say lack of progress—report from the other team.

There was a massive thunderstorm that was pouring rain where they were planning to deploy in Arío, and their truck got stuck in the mud as they were trying to navigate their way to the site. This was horrible but also a little funny considering that just a few nights prior I had mentioned how strange it had been that we had not gotten a field vehicle stuck yet, as this is a textbook fieldwork issue. At that time, Samer assured us that this would not happen since we were there during the “dry” season.

We decide to plow through our current deployment and head to the hotel in case they need backup. This was easier said than done as the digging at our site was nothing short of awful! We managed it, mostly thanks to Oliver, and began our drive to the hotel. As for the other team, after three hours of working nonstop to trying to get unstuck, nothing seemed to be working and the rain wasn’t letting up.

On arrival, we received an update from our incapacitated counterparts. They had managed to get out of the mud… only to immediately get stuck in the mud again on the other side of the road. This was not ideal because now the truck was near a steep drop-off with no guardrail. The situation had become dangerous, and daylight was burning fast. It was 4:30 pm, and sunset was less than 90 minutes away. We offered to attempt a rescue mission to pick up our three-stranded team members, but the drive was nearly 2.5 hours each way and Samer was worried we would end up with both trucks stuck in mud since the rain had not let up.

As a last resort, Samer decided to try digging a trench beneath the mud, and this exhausting approach finally paid off. After the 2.5-hour drive to the hotel, the exhausted and muddy crew made it back safely. We were all relieved and went straight to bed. This was an exhausting day for both teams, and we desperately needed a good night’s rest.

Progress after March 13^th:

On March 10th Oliver, Alexa, and I deployed a site near Cerro Frío that we had scouted a few days prior. We arrived at the landowner’s house to find she had recently sold the property we were originally interested in, thus began our side quest. The landowner had sold the plot of land to some foreigners but put us in contact with the caretaker, who, in turn, put us in contact with his son. This eventually landed us in a teak field. Teak trees are commonly planted by foreigners as a form of long-term investment here since it requires little oversight. It turns out that the leaves of the teak trees are not ideal for the local ecosystem as the leaves are poisonous, even for ants! The trees at our deployment site were only saplings and we set out to work quickly so we could beat the looming raincloud. While the dry season runs from late December to early April in Costa Rica, there was a storm system over the Pacific Ocean that was dumping rain and wreaking havoc on our plans. After successfully finishing right as it started to sprinkle, we stopped for a juice break before making the long drive home to our hotel in Cóbano.

The other team, consisting of Samer, Luis, and Gabriel, successfully deployed a site near the hotel, only a 30-minute drive south of Cóbano. They then proceeded to recover the site at Rio Montaña, which was left to record for one additional day since one of the electrodes was found disconnected when they returned to the site the day prior (it was likely that a horse or cow tripped on the cable while roaming around the field). This unfortunately entailed another 5-hour roundtrip driving voyage. Thankfully, the data upon recovery were high quality, so the extra effort was worthwhile.

Progress after March 10^th:

March 11^th brought the excitement of our first two deployments on islands in the Gulf of Nicoya, but it also brought with it a cloud of sadness. Today we would have to say goodbye to Luis as he returned to San José to prepare for the start of the new semester at Universidad de Costa Rica.

We had lots to get done so we set out early to catch some boats. Upon our arrival at the port, we were met by the newest member of our team, Dr. Kennet Flores. Kennet is a professor at the University of North Carolina Chapel Hill and a Costa Rican local who grew up on the Nicoya Peninsula. In addition to being a native of the area, Kennet has mapped countless geologic formations across Nicoya Peninsula and helped organize our boat rides to and from the gulf islands of Cedro and Caballo.

In our typical fashion, we took a group photo before bidding a sad goodbye to Luis as he boarded the ferry while we set out for Cedros.

The whole team, minus Luis, will be sticking together so that we could all experience the beauty of the Gulf islands.

After a 10-15 minute boat ride where we spotted some pillow basalts along the island’s beaches, we landed on Cedros, a smaller island with a humble village and a small farm.

The locals were kind enough to allow us to deploy in a cattle field on the island, we passed some cows and a friendly bull which Alexa stopped to greet.

From the shore where we docked, we began our journey carrying our deployment equipment. We trekked up a steep hill, through some pasture, up another steep hill, and finally settled on a location we hoped would be far enough away from the island’s main power line.

This was Kennet’s first deployment with us, so we had to show him the ropes. At this point, our team is like a well-oiled machine, and we made great time, completing the deployment in well under an hour! The walk back was much easier than the way up and soon enough we were back on the boat heading to the port.

We decided to power through and head straight to the next port to install a site on Isla Caballo. The drive was around 45 minutes, but with our hopes high from our breezy first deployment, we figured this would be similar. Upon our arrival at the port, we were met with low tide, which meant the usual pull-in for the boats was nonexistent. There was only a muddy canal. Our dream of a breezy deployment sunk in the mud. Never fear, this was only a bump in the road, now all we had to do was trudge through slippery mud carrying some absurdly heavy equipment. No big deal! We completed the perilous walk and managed to do so with only muddy shoes as collateral damage.

This boat ride was much longer, closer to 30 minutes, but we spent it learning about local geology from Kennet and enjoying some gorgeous views.

Once we arrived, we headed to our site, which was a soccer field for the only school on the island. Lucky for us, this deployment would be left over the weekend, and thus we would not have to deal with noise created by the solar panels on the school, the water pump nearby, or the curiosity of the school children. This deployment went smoothly, and the locals on the island were very welcoming! The two sons of our boat driver helped with the deployment by removing a hoard of ants from our bottle of saltwater.

Once we arrived back at the port, the tide was much higher! This was great news as all we had to do was float up to the loading dock and offload ourselves and the very minimal gear we had left after deploying. We loaded into the cars and embarked on the hour-and-a-half drive back to the hotel.

Recently, exhaustion has gotten the better of our traveling party, and thus we have been skipping the pool in favor of falling asleep around 8 pm.

Progress after March 11^th:

March 8^th brought with it plans to move base camp yet again. This time we would be moving a three-hour drive south from Sámara to Hotel Villa Grace in Cóbano, located near the southern tip of the Nicoya Peninsula. We planned to recover one site along the way, but upon arrival, we found that it had only collected six hours of data before the battery died unexpectedly. We decided to replace the battery and leave it for another day. Then, we headed to deploy the site that we had scouted the day before. This deployment was quick and easy thanks to Gabriel’s unmatched digging skills. Oliver laid out the electrode lines and Alexa buried the electrodes, while I prepared the receiver for recording.

This included hooking up the battery and GPS to the receiver and running a receiver calibration that takes around 15 minutes. While this was happening, I made sure to note the serial numbers of all the equipment we were using, including the electrodes, magnetometers, receiver number, and SD card. We do this to identify any malfunctioning equipment and isolate it if something were to go wrong during the recordings.

I also recorded the distances to each electrode. This step is crucial in allowing us to measure the electric field with the electrodes. We get a recording of the electric field in the north/south (E1) and the east/west (E2) directions. Just as a refresher, for the E1 direction, north is the positive direction, and south is the negative direction. For E2, east is positive, and west is negative.

The MT receivers record the potential difference between the positive electrode and the ground and the negative electrode and the ground (for the ground, we either used a metal rod or another electrode) for both E1 and E2. The potential difference is simply a voltage reading, like when you measure the voltage on a car battery. However, we are interested in measuring the electric field, which has units of volts per meter. Therefore, to convert this potential difference reading into an electric field measurement, it must be divided by the length of that electrode wire, which is why it is essential to record the electrode separation distances in the field.

Once the calibration was finished, and we had all the electrode distances, I removed the SD card and programmed it to record MT data. I made sure to input the electrode line distances, change the recording settings so that we didn’t use up all the SD card memory,  input the type of magnetometers we were using, and then saved these settings back onto the SD card. After this, all that was left was to copy the calibration file from the SD card before removing it from the computer and placing it back into the receiver. Then, I turned on the receiver and waited for it to get a GPS lock (essentially, wait for it to get a lock on GPS satellites so that the receiver can keep a very accurate record of the time). While I waited, I took the time to fill out the installation sheet. This is a spreadsheet we use at every site to record serial numbers, distances, and every detail we need about the site. Once we got the GPS lock, I started the recording. The receiver ran a few tests to make sure all the equipment was working correctly. Then, it spits out some values for electrode contact resistance and DC voltage, which also had to be recorded in the field notebook and the spreadsheet. If the resistance values were less than 10,000 ohms (better still, less than 1,000 ohms) and the DC voltages less than 0.1 V, we were good to pack up and leave the equipment to do its thing.

After our deployment, it started to rain. Rain is unusual this time of year in this part of the world. Unfortunately, our kitty litter in the bed of the pickup truck did not fare too well.

Progress after March 8th:

The issue of the rain persisted into March 9^th where it “soiled” our plan to deploy early in the morning. The team consisting of Samer, Luis, David, and Gabriel went to recover several sites and swap batteries at the semi-permanent site in Hojancha that required way more driving than would be preferred (nearly four hours round trip!). They also would be dropping David off in his hometown (which was conveniently close to one of their recoveries). College would be starting soon and David’s short time with us was sadly coming to an end.

Alexa, Anna, and Oliver had planned a deployment in a nearby mango farm, but this had to wait until after the rain cleared. While waiting we went to a nearby restaurant for lunch.

Deploying in the rain itself is not fun, and it gets even less fun when you consider that around half of the roads outside of towns on the Nicoya Peninsula are dirt roads that quickly turn into mud when water is added to the mix.

These can quickly become mud pits for your car to get stuck in if you are not careful, thus we decided to err on the side of caution. We managed to deploy later that afternoon when Samer’s group returned. The mango field was gorgeous, and the digging was quite easy. This farm is intended for exportation so we were not allowed to take any of the mangos for ourselves, which was a little sad but also this was the least we could do given that the landowners graciously gave us permission to dig holes on their property.

Progress update after March 9^th:

March 6^th was the first solo mission for me, Oliver, and Luis, and in typical fashion, things didn’t go as planned for us. We spent hours scouting for an ideal site to deploy an instrument, but apparently in the wrong area all along.

A bright side to this is that we saw this crazy looking animal! I managed to grab a photo before it scurried off in a hurry. A few google searches later we found that it was a pizote. This can also be called white-nosed coatimundis.

After our scouting extravaganza, we ultimately found a location to deploy a site. However, the directions we were given by the landowner led us to the wrong property so we had to backtrack and contact the landowner once more. This slowed us down yet again, and we ran out of time and had to hold off on the deployment until the next day. To top off this disappointment of a day, the drive back to the beach house in Sámara was around 2 hours. We set off to try to get back in time for dinner. While our group was sorting through logistical issues, the other group (Samer, Alexa, and Gabriel) blew through their deployment and managed to recover a few sites. This was enough to keep us mostly on track for the day! While we have suffered some consequences when splitting up, this increase in productivity is a huge benefit.

Progress update after March 6^th:

On the following day, March 7^th, we were on a mission to actually get the delayed deployment completed. This time around we were joined by a friend of Luis, fellow geology student and Guanacaste native David Rodríguez. Oliver, Luis, David, and I planned to deploy a site and then scout for another site afterward, this time in the correct area. The deployment went smoothly!

This was my first fully solo deployment running the computer and setting up the instrument without Darcy or Samer there to watch over me. While this was nerve-wracking, it was also a good way to test my abilities. To be certain the receiver was functioning as planned, I decided to run a 10-minute test recording. We do this by simply starting the receiver and then pulling the SD card out after 10 minutes to check and make sure the preliminary data looks good and to make sure the receiver is logging the signal. In this case, it was successful! This is what the data looked like after 10 minutes:

Notice how the data looks really noisy between 10 to 0.1 Hz frequencies (along the x-axis). This is because of the “dead band” in the MT signal. The dead band is where the higher frequency signal we obtain from global lightning activity (this will be detailed in another blog post soon!!) ends and where we transition to the lower frequency signal generated from the interaction of solar wind with the geomagnetic field (see blog post ). Because of this, there is an area in between these two sources where not much natural signal is produced.  Here is a quick plot that shows where our MT signal is from to hold you over until the lighting signal post:

Otherwise, the higher frequency data (>10 Hz) looked smooth, which gave me confidence that this was a good site and that all was working as expected. This is what we expect good data to look like after it has had enough time to average out the low signal in the deadband:

After this successful deployment, we moved on to the scouting portion of the day in the designated area, which was around an hour’s drive away.

On arrival, we found a gorgeous field that would work great for deployment; this is the easiest part of scouting. The issue of locating the owner of the said land is where things get tricky. We typically go around asking locals walking along the street or the residents of nearby houses. In this case, we were able to skip the trial and error because David said he knew the landowners and quickly led us to their house. This was amazing and cut out a large portion of the time spent scouting! Luis and David obtained permission for deployment in record time! We did not have a full deployment kit, so we would have to return the following day, but this still saved a huge amount of time.

The other team (Samer, Gabriel, and Alexa) managed to scout and deploy an unplanned site in a remote mountainous area and proceeded to another site near the scenic beach in Ostional, completing two deployments! All in all, this was a successful day that was reassuring after Darcy’s recent departure.

Progress update after March 7:

The next two days we planned were relatively mild, mainly due to Darcy abandoning us on March 6th. The plan for March 4^th was to knock everything out in the morning so that we could have the time after lunch to prepare for the beach grill dinner which doubled as Darcy’s sendoff party.

We split into two groups which was now needed because now our group of seven has become too large to fit into one car with five seats. This consisted of Group A (Darcy, Anna, Alexa, and Gabriel) and Group B (Samer, Oliver, and Luis). Group A drove out to a beautiful, flat site right next to the beach! Alexa, having tried her hand at electrode burying the day prior, acclimated quickly to the workflow of a deployment.

After Darcy leaves for home, I will resume the responsibility of calibrating and programming the receiver to collect data. This was a little nerve-racking as this trip is my first time handling MT instruments, so I spent this particular deployment reviewing the workflow with Darcy.

This deployment seemed to be going smoothly and we finished the installation in around 50 minutes. However, before leaving a site, we always make sure to check the electrode resistances, and at this site, it’s a good thing we did. Our north electrode line was reading a ground resistance of 175,000 ohms. This was alarming since the normal range is between 100 and 10,000 ohms. When the receiver shows such a large resistance, it essentially means “this instrument is not able to measure anything, so I’m giving you the highest value I can record to tell you something is wrong”. We gave the north electrode a check and sure enough, the connection between the electrode and the 50-meter cable was loose and not working properly. Darcy removed the connectors and directly spliced the 50-meter cable directly to the electrode cable. This resolved the issue and we were on our way after only a brief 15-minute hiccup.

Meanwhile, Group B (Samer, Oliver, and Luis) headed up into the mountains to complete a deployment. The goal of finishing work for the day in the early afternoon was a complete success, and we began to prep for the beach grill-out. Our grill master, Samer, had a feast planned. We would have fresh fish, lobster, steak, grilled vegetables, queso fresca and more. For appetizers, Luis made a spicy tuna fish dip, refried beans, and pico de gallo. I contributed a fruit salad of bananas, fresh mangos, and apples.

Below are photos from the grill out!

I tried my best to rally the troops to go swimming with me. This is the part where I learned more than half of our group was skeptical (aka afraid) of swimming in the ocean! Samer and Darcy were the only ones who listened to my call to action. The others watched from the shore.

Progress update after March 4th

On March 5^th we ate our last group breakfast at Casa Zerimar (shown below). Luis and Gabriel made gallo pinto, a delicious traditional Costa Rican breakfast consisting of rice, beans, and eggs.

We also planned a light schedule as this would be Darcy’s last day with us. We split into different groups compared with yesterday. These would be the groups that we would try to stick with after Darcy’s departure. Group A is me, Oliver, and Luis (with Darcy shadowing us for the day to make sure we have everything under control) and Group B is Samer, Alexa and Gabriel. Group A went to recover one site and change the batteries on the current permanent site (the one with the big tree). The recovery went quickly (like almost every recovery), and we attempted to pick some mangos from this cute mango tree (shown below), but sadly they were still not ripe.

At the permanent site, Darcy, Luis, and I took a stab at climbing the gorgeous tree (shown below). We did this while we ran a 15-minute data test because when we went to replace the battery, we saw that the last two-day run had collected no data! While this was a bummer, we simply swapped the batteries and took some extra precautions to make sure the recording would work this time around.

After finishing up at the permanent site, we headed to meet up with Group B while they finished their deployment. They had scouted and gotten permission for this site all in the same day (this is super lucky). We caught the tail end of the workflow and jumped in to help.

Afterwards we took a quick group photo (shown below) and piled back into the cars to get some ice cream from the Nicoya location of Pops (an ice cream chain in Costa Rica) before bidding farewell to Darcy.

March 2^nd was a big day, this was when our two new team members, Oliver Azevedo, and Alexa Fernández, were set to fly into the Liberia airport. Oliver Azevedo is a first-year Ph.D. student at Georgia Tech in the EGL group and Alexa Fernández is a Costa Rican native currently working on her Master’s degree at the University of Nebraska Lincoln. Their arrival was great news as we would be able to deploy and recover sites fasters.

This was also great news for me, Luis, and Gabriel as it meant that while Samer and Darcy made the drive to the airport, the three of us got to take the day off! We spent our time relaxing; I had some time to work on the blog and do a few paintings. Samer and Darcy had to pick up a few sites before heading to the airport; both of them made the drive because the addition of two more people meant we would require another truck. At the time we only had one truck and a small SUV (which was essentially useless for reaching some of the remote and treacherous sites we were deploying). This SUV will be returned when Darcy leaves on March 5^th, leaving the group with the ideal scenario of two hardy 4×4 trucks. Once Darcy dropped off Samer at the airport and returned from Liberia, the only task we had to do was replace the batteries at the semi-permanent site, NIC-23. This was done by Darcy and Luis while Gabriel and I waited on the arrival of our new team members. Samer, Alexa, and Oliver arrived at the hotel around 5:30 pm after stopping to recover the former semi-permanent site. Nothing quite like an MT instrument recovery after a plane ride to get your blood pumping! Once they arrived we all headed to dinner. Then in our usual fashion, we headed to the pool shortly after.

The next day, March 3^rd, we moved from our current hotel in the city of Nicoya to the coastal town of Puerto Carrillo near Sámara, where we stayed in the beach house of our gracious field coordinator, Carlos Ramírez. This same day, we hatched a plan motivated by the upcoming departure of the project co-lead, Darcy Cordell. We planned to deploy four sites on the 3^rd to allow for a chill day on the 4^th, complete with a goodbye party before his departure on the 5^th.

As usual, this day did not go as planned. The group of Darcy, Alexa, Gabriel and I only managed to recover the 30-degree downslope site (which had data this time! Yay!).

We then spent the rest of the morning essentially driving around. We hit a lot of walls in terms of getting permission for deployments and finding houses without any owners at home. Luis, Oliver, and Samer managed to secure one deployment much further inland near Nicoya. Afterward, they gathered the luggage from the hotel to make the two-hour drive down to the beach house near Sámara. My team had hit so many dead ends, we decided to reconvene with the other team once they arrived at the beach house. It was around 1 pm and our plan of four deployments was looking absolutely shot, with our running total being one deployment. It was also hot and muggy near the coast, far more humid than inland and we were all feeling like blobs ready for a nap.

This is when permission was miraculously granted for a site only 10 minutes away from the house! After rallying my team in the heat, we headed out. The landowner who met us was so kind and took the time to show us a seep on his property (a location where water is leaching up from the deep subduction plate interface).

This deployment was difficult, very steep, very hot, and lots of walking, but we did it! This was Alexa’s first deployment with us (very exciting)! I sadly did not get any pictures mainly due to the challenging conditions at the site. When we returned home, the other team, which we thought had left to get groceries around the same time we left was still not home. This was peculiar, but we presumed they were just taking their time at the grocery store, or had gone for a walk to explore the town. It was so hot and, when we left to deploy our site, they for sure were not going to be doing any more work that day.

Since the beach is less than a five-minute walk from the house, Darcy and I went swimming! We got absolutely destroyed by some intense waves, the amount of salt water in my sinuses was at an all-time high. Alexa, Darcy and I caught a gorgeous sunset over the Pacific.

After making it back to the house at dusk, Oliver, Samer, and Luis arrived back with word of another deployment! This was monumental! The story we heard was that they went to scout the site but then Luis persuaded them to simply power through and deploy the site right then and there.

We were very surprised given the muggy heat and the fact that the last thing we heard from them was “no way are we deploying another site today!”. Samer claims that it was the deafening roar of cicadas that gave Luis the energy to push through the late afternoon deployment. All in all, this means we had managed to get three out of the four planned sites installed for the day. It wasn’t all a wash after all! To end this surprisingly successful day, we then walked to dinner at a location suggested by Carlos down the road and enjoyed fresh seafood and papanachos (like nachos but with plantains).