index.qmd

---
title: La Palma Earthquakes
author:
  - name: Steve Purves
    orcid: 0000-0002-0760-5497
    corresponding: true
    email: steve@curvenote.com
    roles:
      - Investigation
      - Project administration
      - Software
      - Visualization
    affiliations:
      - Curvenote
  - name: Rowan Cockett
    orcid: 0000-0002-7859-8394
    corresponding: false
    roles: []
    affiliations:
      - Curvenote
keywords:
  - La Palma
  - Earthquakes
abstract: |
  In September 2021, a significant jump in seismic activity on the island of La Palma (Canary Islands, Spain) signaled the start of a volcanic crisis that still continues at the time of writing. Earthquake data is continually collected and published by the Instituto Geográphico Nacional (IGN). ...
plain-language-summary: |
  Earthquake data for the island of La Palma from the September 2021 eruption is found ...
key-points:
  - A web scraping script was developed to pull data from the Instituto Geogràphico Nacional into a machine-readable form for analysis
  - Earthquake events on La Palma are consistent with the presence of both mantle and crustal reservoirs.
date: last-modified
bibliography: references.bib
citation:
  container-title: Earth and Space Science
number-sections: true
---

## Introduction

```{r}
eruptions <- c(1492, 1585, 1646, 1677, 1712, 1949, 1971, 2021)
n_eruptions <- length(eruptions)
```

```{r}
#| label: fig-timeline
#| fig-cap: Timeline of recent earthquakes on La Palma
#| fig-alt: An event plot of the years of the last 8 eruptions on La Palma.
#| fig-height: 1.5
#| fig-width: 6
par(mar = c(3, 1, 1, 1) + 0.1)
plot(eruptions, rep(0, n_eruptions), 
  pch = "|", axes = FALSE)
axis(1)
box()
```

```{r}
#| output: false
avg_years_between_eruptions <- mean(diff(eruptions[-n_eruptions]))
avg_years_between_eruptions
```

Based on data up to and including 1971, eruptions on La Palma happen every `{r} round(avg_years_between_eruptions, 1)` years on average.

Studies of the magma systems feeding the volcano, such as @marrero2019, have proposed that there are two main magma reservoirs feeding the Cumbre Vieja volcano; one in the mantle (30-40km depth) which charges and in turn feeds a shallower crustal reservoir (10-20km depth).

Eight eruptions have been recorded since the late 1400s (@fig-timeline).

Data and methods are discussed in @sec-data-methods.

Let $x$ denote the number of eruptions in a year. Then, $x$ can be modeled by a Poisson distribution

$$
p(x) = \frac{e^{-\lambda} \lambda^{x}}{x !}
$$ {#eq-poisson}

where $\lambda$ is the rate of eruptions per year. Using @eq-poisson, the probability of an eruption in the next $t$ years can be calculated.

| Name                 | Year   |
| -------------------- | ------ |
| Current              | 2021   |
| Teneguía             | 1971   |
| Nambroque            | 1949   |
| El Charco            | 1712   |
| Volcán San Antonio   | 1677   |
| Volcán San Martin    | 1646   |
| Tajuya near El Paso  | 1585   |
| Montaña Quemada      | 1492   |

: Recent historic eruptions on La Palma {#tbl-history}

@tbl-history summarises the eruptions recorded since the colonization of the islands by Europeans in the late 1400s.

![Map of La Palma](images/la-palma-map.png){#fig-map}

La Palma is one of the west most islands in the Volcanic Archipelago of the Canary Islands (@fig-map). 

{{< embed notebooks/explore-earthquakes.qmd#fig-spatial-plot >}}

@fig-spatial-plot shows the location of recent Earthquakes on La Palma.

## Data & Methods {#sec-data-methods}

## Conclusion

## References {.unnumbered}

:::{#refs}

:::